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Unmanned Spaceflight.com _ Venus Express _ Venus Express

Posted by: tedstryk Apr 12 2005, 06:56 PM

If all goes well, Venus Express will be a major topic for discussion in this forum a year from now. Does anyone know how good the surface coverage will be from VIRTIS and VMC? My understanding is that VIRTIS will obtain low resolution multispectral maps, and that VMC will, in addition to cloud monitoring, have one channel that can see the surface, but I don't know at what resolution or at what quality. It will be nice to have some non-radar images of Venus' surface besides the Venera snapshots and the shadowy images from Earth and Galileo's NIMS.

Ted

Posted by: BruceMoomaw Apr 20 2005, 10:31 AM

See my new note on the "Radar on Venus Express?" thread, Ted. I may be able to get you some more precise resolutional data later on if I can find the time. (However, VMC -- unlike VIRTIS -- cannot see the surface; it's entirely for UV cloud top patterns.)

Posted by: tedstryk Apr 21 2005, 03:16 AM

Actually, VMC will have some limited capabliity to detect the surface. My source on this is the ESA mission documentation. See below:

3.7 VMC (Venus Monitoring Camera)
Precursors. Imaging of the Venus disc at different wavelength was carried out by the Pioneer Venus orbiter, during the fly-bys of Mariner-10 and Galileo, and from the ground. These data was used to study the atmospheric dynamics at the cloud tops (UV), to investigate the thermospheric dynamics (UV, visible, and near-IR airglow), to map the surface brightness and to study cloud opacity variations (near-IR). However, these observations lacked global spatial and temporal coverage as well as spatial resolution. At the same time they demonstrated the power of the global imaging in the study of dynamical processes in the Venus atmosphere.
VMC/Mars Express. The Video Monitoring Camera (VMC) onboard the Mars Express is a monochrome wide-angle CCD camera that was designed to take the video sequence of Beagle-2 lander leaving the Mars Express spacecraft at Mars.
VMC/Venus Express. The Study Team has recommended to modify the Mars Express camera into a wide-angle multi-channel Venus Monitoring Camera. The modification will consist of adding several narrow band filters in the UV, visible, and near-IR spectral ranges that would allow the camera to provide support imaging for the whole mission, achieve additional science goals, and contribute to the public outreach programme. Preliminary study showed that the modification of VMC will not specify additional requirements to the Mars Express bus and will be fully compatible with spacecraft interfaces. More detailed elaboration of the technical, programmatic, and financial issues related to the VMC modification and accommodation on the spacecraft will be done by the VMC team, Astrium, and ESA during the pre-Phase B study in the beginning of 2002 if the mission is approved. The modified VMC will be prepared in parallel with available VMC/Mars Express in order not to jeopardize the schedule of the mission. In case of failure to modify VMC in time VIRTIS will be able to cover significant part of the VMC goals so that the achieving of the mission objectives would be secured.
The VMC camera will be capable of achieving scientific goals in atmospheric dynamics and surface studies by means of global multi-channel imaging. An example of UV image expected from VMC at Venus is shown in Figure 2.2. Sequence of such images would allow one to visualize the motions of the cloud tops and to study the general circulation and wave phenomena at the altitude of ~70 km. Images of the Venus disc taken every 30 min will be used to create movies of the cloud motions and propagating waves that would be extremely valuable for investigation of the atmospheric dynamics. Figure 2.6 shows an example of image that VMC will take in the visible at night. The monitoring of airglow patterns that originate at 90-110 km is an efficient tool to study the dynamics of the Venus upper atmosphere. The VMC observations in the 1 m transparency “window” will give the images similar to those shown in Figures 2.5 and 2.9. These images have two types of features. Some of them belong to the surface and result from the temperature and emissivity variations. Second type of markings originates in the main cloud deck and indicates cloud opacity variations. The movies based on such imaging will be used to study global atmospheric dynamics at ~50km.
To summarize, VMC will fulfill the following scientific goals:
• Support imaging, i.e. global imaging context for the whole mission;
• Observations of the global cloud motions in the UV and near-IR spectral ranges;
• Study of distribution of the unknown UV absorber at the cloud tops;
• Monitoring the UV and visible airglow and its variability as dynamical tracer;
• Mapping the surface brightness temperature distribution and search for volcanic activity.
Besides important scientific goals the VMC imaging and movies will significantly contribute to the public outreach programme.

Posted by: BruceMoomaw Apr 21 2005, 05:34 AM

You've caught me -- I was completely unaware of VMC's near-IR sensitivity. Very embarrassing.

Posted by: Mode5 Apr 21 2005, 05:53 AM

To the powers that be, thank you for creating this forum. It is the first I heard of this mission.

I am fascinated by Venus and looking forward to it now. It sounds like they are interested in studying the atmosphere extensively. Some of the questions they want to answer:

"What are the global characteristics of the atmosphere?"
"How does it circulate?"
"How does the composition of the atmosphere change with depth?"
"How does the atmosphere interact with the surface?"
"How does the upper atmosphere interact with the solar wind?"

The understanding and possible control/conversion of greenhouse gasses on Venus could directly benefit us on Earth. Terraform Mars? Too easy; I say we go for Venus! wink.gif

Here are some excellent Magellan images of the surface.
http://www2.jpl.nasa.gov/magellan/images.html

Posted by: Gsnorgathon Apr 21 2005, 07:08 AM

Ted - do you have a link for the ESA mission doc(s)?

Posted by: tedstryk Apr 21 2005, 09:17 AM

http://megasn.obspm.fr/VEX_MDR51.doc

It is a bit dated in terms of VENSIS still being listed, but I don't think anything lese has changed.

Posted by: djellison Apr 21 2005, 09:26 AM

I wonder if the effects of looking thru narrow spectral bands will result in the sort of quality we get at Titan - or something a bit better than that

Doug

Posted by: tedstryk Apr 21 2005, 09:51 AM

Hard to tell. It is sort of like Pre-Cassini Titan, in that the limiting factor in all images we have is the resolution of the detector, so we don't know just how well we will be able to see. I will research this a bit more and see if I can dig up any speculation. Still, if Venus Express can take images at Cassini/ISS Titan resolution, they will look even more spectacular, because Venus is so much larger. And at last we will have some global multispectral data (although some data to this effect has been assembled from different Radar systems (PVO, Magellen, Venera, and the earthbased collection).

Anyhow, it seems the VMC, while it is a clone of the "Beaglecam" on Mars Express, seems to be hav converted in to quite a good little science instrument. Here is the info from the regular Venus Express website:
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33964&fbodylongid=1448

Posted by: BruceMoomaw Jun 23 2005, 12:06 AM

I can dig up some stuff on this for you, given a little more time (sorry it took me so long to even notice the question). As I recall, they're hoping for a resolution of roughly 30-50 km in VIRTIS' near-IR surface maps at Venus' poles, where it will be best -- but that may be just for its possible mineral maps, with the resolution of its actual albedo maps being a lot better.

Posted by: remcook Jun 25 2005, 08:28 PM

I believe the spectral 'windows' are much less clear than for Titan, but for Galileo NIMS, some people have made temperature maps of the surface, clearly showing topography. quite cool cool.gif

Posted by: edstrick Jun 26 2005, 07:02 AM

My understanding is that the topographically related infrared brightness variations seen by Galileo at Venus were diffused through the lower atmosphere and then the dense middle cloud deck.

VIMS' middle infrared visibility of Titan's surface is quite good, compared with poor visibility and high amounts of diffuse scattering of reflected light in the 1 micrometer 'window" as seen by the Cassini imaging system.

My understanding is that at Venus, the atmosphere has no non-scattering transmission till you reach microwave wavelengths. Basically, imagine holding a sheet of blotchy waxed paper 50 km above the planet's surface and examining the diffuse patterns on the waxed paper from variable amounts and colors <spectral emissivity variations> of the surface below. The blotches will be constantly varying with time and location, but the color and brightnesses of the glow from beneath will be constant, and the color especially, can be separated from the blotchy cloud patterns <which themselves are interesting>

Posted by: Richard Trigaux Jun 26 2005, 08:06 AM

QUOTE (tedstryk @ Apr 21 2005, 09:51 AM)
It is sort of like Pre-Cassini Titan, in that the limiting factor in all images we have is the resolution of the detector, so we don't know just how well we will be able to see.


I think the main limiting factor in Cassini was not the instruments themselves, but the radio bandwidth available, together with very brief observation opportunities. This was all the more true for Huygens, which images were ridiculously small and tremendously compressed.

With Venus we have more solar power, and a much shortest distance. And, in orbit, we have the possiblity to take hundreds of images of the same surface part, and so to statistically eliminate the effects of cloud features.

Posted by: edstrick Jun 26 2005, 10:31 AM

On Cassin, the VIMS is the best instrument we could design with early 90's mid-infrared imaging technology.

We now have real mid-infrared imaging detectors. Not 10 megapixel, but still real camera chips, that can take quality images with really good resolution in the mid-IR (1 to 5 micrometers, more or less). We just @#$@# didn't back then.

Posted by: maycm Jul 8 2005, 12:49 PM

An update....though not much new information.

http://www.spacedaily.com/news/venus-05a.html

Posted by: Bob Shaw Jul 8 2005, 01:59 PM

QUOTE (edstrick @ Jun 26 2005, 11:31 AM)
On Cassin, the VIMS is the best instrument we could design with early 90's mid-infrared imaging technology.

We now have real mid-infrared imaging detectors.  Not 10 megapixel, but still real camera chips, that can take quality images with really good resolution in the mid-IR  (1 to 5 micrometers, more or less).  We just @#$@# didn't back then.
*


Well, obviously we need a Shuttle mission to replace the instrument...

Posted by: JRehling Jul 8 2005, 02:23 PM

QUOTE (edstrick @ Jun 26 2005, 03:31 AM)
On Cassin, the VIMS is the best instrument we could design with early 90's mid-infrared imaging technology.

We now have real mid-infrared imaging detectors.  Not 10 megapixel, but still real camera chips, that can take quality images with really good resolution in the mid-IR  (1 to 5 micrometers, more or less).  We just @#$@# didn't back then.
*


It seems apparent that the 938nm wavelength, which is the best one ISS has to use on Titan, is not the best penetrator of Titan's haze, and that VIMS can thereby make up for (some of) ISS's edge in intrinsic resolution by utilizing better IR wavelengths. Not only by choosing the best possible single wavelength (the best ones are longer than 938nm, at other spectral "holes"), and taking one-wavelength images in that. Surely VIRTIS will beat ISS in that respect. On the other hand, CO2 will block different holes than CH4, and I'm not sure if it leaves us a better hole than CO2 or not.


I think the best IR products of Venus's surface will come from compiling repeated coverage of the same areas and "stacking" or somehow integrating the data to average out over varying cloud thicknesses.

Finally, note that IR is complicated terribly at Venus, but not at Titan, by thermal effects. If all we see is a thermal record of the surface, then we may not get much more than crude altimetry we already knew about. Sorting out the albedo may be impossible.

Posted by: Gsnorgathon Jul 9 2005, 04:10 AM

I suppose it's possible, if not easy, to subtract images taken at night from daytime images. "Not easy" might be too much of an understatement.

Posted by: JRehling Jul 9 2005, 05:09 AM

QUOTE (Gsnorgathon @ Jul 8 2005, 09:10 PM)
I suppose it's possible, if not easy, to subtract images taken at night from daytime images. "Not easy" might be too much of an understatement.
*


One problem is, can you project an image onto a map accurately? It depends upon whether you are looking at a cloud-level sphere or a surface sphere. And there is undoubtedly refraction. My guess is that you would assume that a cloud level sphere is what you're looking at, assume that when you look at a point in the clouds you are trying to collect albedo data from a diffuse area centered below that point, and use multiple images to integrate observations.

Subtracting night from day -- what does this buy? There will be a lot of thermal interference at both times, but you can't assume that it is precisely the same. You'll get some combination of thermal inertia and albedo -- messy!

When it comes right down to it, trying to observe Venus from above the clouds and learn a lot is pretty tricky. Unless some mineral of interest has a heck of a wicked IR spectrum and that happens to fall inside one of the CO2 windows, I'm just plain skeptical that we'll get good geological data from this mission. Hope I'm wrong.

Surface spectra are, IMO, going to have to come from below the clouds. That still doesn't solve the problem of atmospheric interference, but the fact that the horizons are so clear in Venera imagery provides a lot of cause for optimism. A camera-to-horizon "chord" of 5km will cut through more than or the same as atmospheric interference than a vertical line from surface to clouds (surface air is the densest, and a horizontal chord is entirely through dense air, whereas a vertical slice only goes through the densest air at the bottom). So, with clear images at the surface, I think we can get good images from several km up. A balloon could do the trick.

Posted by: TheChemist Aug 10 2005, 04:33 PM

http://www.esa.int/esaCP/SEMNBT808BE_index_0.html

She's got it ..... (Am I allowed to quote Bananarama in a space forum ? smile.gif )

Posted by: Bob Shaw Aug 10 2005, 07:42 PM

QUOTE (TheChemist @ Aug 10 2005, 05:33 PM)
http://www.esa.int/esaCP/SEMNBT808BE_index_0.html

She's got it ..... (Am I allowed to quote Bananarama in a space forum ?  smile.gif )
*


It ain't what you do, it's the way that you do it!

Posted by: BruceMoomaw Aug 29 2005, 02:10 AM

Here's my long-promised entry on whatever I've got regarding VIRTIS' possible ability to map Venusian surface composition.

Unfortunately, the two most important documents on this aren't available for free on the Web: the Nov. 2000 Icarus article by Langevin et al ("Detection of Sub-Micron Radiation from the Surface of Venus by Cassini/VIMS"), and the March 2002 article by V.I. Moroz in "Planetary and Space Science" ("Estimates of Visibility of the Surface of Venus from Descent Probes and Balloons"). I have a photocopy of the former, but can't find the copy I thought I had of the latter. Anyway, the former is optimistic about the possibility: "The 5 spectral windows between 0.85 and 1.18 microns now proven to be sensitive to surface spectral sensitivity provide a potentially effective means for remotely mapping the mineralogical composition of the surface of Venus" [something co-author Kevin Baines was saying for previously]... [They] can be effectively used to distinguish ferric (hematite) and ferrous minerals (e.g., the pyroxenes augite and hypersthene, and olivine). The hydrous mineral tremolite -- thought to be stable on geologic timescales on Venus -- also displays a detectable absorption feature...Both wollastonite -- a CO2 buffer mineral thought to be relating the CO2 surface pressure -- and pyrite are spectrally flat, but have distinctly different ablbedos." There's an accompanying graph of these various minerals' near-IR reflectivities, with the Venusian surface spectral windows overlaying it.

The Moroz article is much more pessimistic: "Constraints on the mineral surface composition would be difficult to derive from orbital observations due to multiple reflections between the surface and the atmosphere." The VIRTIS group itself, the Japanese VCO group and the Vernadsky-Brown Venus group are all intermediate in optimism: they think that it will almost certainly be possible to map FeO, thus distinguishing between felsic and mafic minerals and thus between granites and basalts, and also looking for magnetite on the highly radar-reflective mountaintops -- but aren't sure they can go any farther. (The two longest-wavelength windows seem to be the most useful.) Moreover, it seems much more possible to do this in the north polar regions than elsewhere (which, by an agreeable coincidence, is where Ishtar Terra -- Venus' most likely continent -- is located).

As for spatial resolution (including for temperature and near-surface volcanic gases), estimates are all over the place. Moroz sets it at 50-100 km, the VCO group at 100 km, and David Crisp at no better than 250 km (based on Galileo's flyby results). The VIRTIS group itself initially set it as high as 30 km, but now seems to have it pegged at 90-150 km ( http://irsps.sci.unich.it/~luciam/VEX/DOC/SurfaceScience_VIRTIS.pdf and the May 2005 report at the VIRTIS site: http://irsps.sci.unich.it/~luciam/VEX/ ).

As for quake detection through sensing pressure waves in Venus' dense CO2 air, they are still very interested in that -- although it will require special observational techniques (see the Dec. 2003 and May 2005 reports at the VIRTIS site).

Posted by: BruceMoomaw Aug 29 2005, 02:15 AM

Two more notes:

(1) The VIRTIS team is fully ready to filter out altitude effects from their maps, using Magellan's altimetry maps (see their May 2005 report).

(2) There's another good paper on the possible detection of Venusquakes through atmospheric pressure waves at http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2274.pdf .

Posted by: tedstryk Sep 11 2005, 01:35 PM

http://messenger.jhuapl.edu/the_mission/images/timeline_full_sm.jpg

You gotta love the ESA press people.

"Venus Express will be making the first global examination of the atmosphere of Venus."

Pioneer Venus Orbiter? And to some degree the Venera orbiters?



"The scientific teams of the seven very precise instruments and multi-wavelength cameras on board expect to collect infinitely more science data than all previous missions combined - with the exception of Magellan – more than 500 megabits of data received every day."

Yes, it is a lot more than missions besides Magellan, but infinite? I think there is a bit of grandstanding here. rolleyes.gif

Posted by: mike Sep 12 2005, 07:08 PM

America will just have to make a new probe that returns infinitely more data than the infinite amount ESA is getting.

Posted by: 4th rock from the sun Sep 12 2005, 08:46 PM

QUOTE (tedstryk @ Sep 11 2005, 02:35 PM)
...

Pioneer Venus Orbiter?  And to some degree the Venera orbiters?

...

Yes, it is a lot more than missions besides Magellan, but infinite?  I think there is a bit of grandstanding here.  rolleyes.gif
*



If the PVO data where avaliable on the net this type of statement wouldn't be possible. Someone would gather that data and make some time lapse movies, global maps, etc, etc.

The best I could find is this: http://www.cg.its.tudelft.nl/~freek/venus/report/last_results/04-07.htmlhttp://www.cg.its.tudelft.nl/~freek/venus/report/last_results/04-07.html
Not much really.

So no wonder that ESA is selling their "product" as best as they can!

Posted by: Bob Shaw Sep 12 2005, 09:04 PM

QUOTE (mike @ Sep 12 2005, 08:08 PM)
America will just have to make a new probe that returns infinitely more data than the infinite amount ESA is getting.
*


Mike:

It wouldn't take all that much more!

Oh, and the thing that the ESA Press Office left out is that they'll also be releasing the Venus Express data infinitely s-l-o-w-l-y...

Bob Shaw

Posted by: tedstryk Sep 12 2005, 09:59 PM

Well, I doubt there would be time-lapse images. The cloud photopolarimeter built scans slowly like Pioneers 10 and 11, so there wouldn't be many sequences close enough together, and changes in position throughout the scan would be a problem.

Posted by: TheChemist Sep 13 2005, 11:52 AM

QUOTE
Oh, and the thing that the ESA Press Office left out is that they'll also be releasing the Venus Express data infinitely s-l-o-w-l-y...

laugh.gif laugh.gif
Although "infinitely more" is a very common expression and should not be taken literally. the ESA press office really deserved this biggrin.gif

Posted by: tedstryk Sep 13 2005, 03:01 PM

QUOTE (TheChemist @ Sep 13 2005, 11:52 AM)
laugh.gif  laugh.gif
Although "infinitely more" is a very common expression and should not be taken literally. the ESA press office really deserved this  biggrin.gif
*


Yes, but especially when compared with PVO, even in common usage it doesn't fit (well, maybe in shear bits, but not in the scope of investigations)

Posted by: RNeuhaus Oct 12 2005, 04:09 AM

New update. Now it is less than 14 days from launching on October 26 from Baikonour Cosmodrome.

http://www.esa.int/SPECIALS/Venus_Express/SEMTXB5Y3EE_0.html

* Propellant loading already completed. Two tanks with more than 260 liters capacity.
* Venus already has its wings. Provides 1,100 watts of power. It is made of Gallium Arsenide Triple Junction
* Electrical test completed. Automatic sequence of maneuvers works.

Almost ready for a trip of 153 days toward to Venus for a mission of 500 days in Venus orbit.
Launch mass is 1,270 kg.

Rodolfo

Posted by: ljk4-1 Oct 13 2005, 01:50 PM

Preparations for ESA's Venus Express mission passed a new milestone when the
spacecraft was attached to its Fregat upper-stage rocket. The mission is now
only two weeks away from launch on 26 October.

More at:

http://www.esa.int/SPECIALS/Venus_Express/SEMTYW5Y3EE_0.html

Posted by: RNeuhaus Oct 13 2005, 02:45 PM

The spacecraft Technical details

Spacecraft facts
Spacecraft bus dimensions 1.5 x 1.8 x 1.4 m
Spacecraft mass 1270 kg (including 93 kg of payload and 570 kg fuel)
Thrust of main engine 400 N
Attitude thrusters Two sets of four, each delivering 10 Newtons each
Solar arrays Two triple-junction Ga As;
5.7 square metres; generating 800 Watts
near Earth and 1100 Watts at Venus
Power storage Three lithium-ion batteries
Antennas Two high-gain dishes, HGA1 = 1.3 m diameter,
HGA2 = 0.3 m in diameter, 2 low-gain antennas

http://www.esa.int/SPECIALS/Venus_Express/SEMEE3808BE_1.html#subhead1

The proportion of total weight versus fuel is 44.8% of weight is fuel comparing to the MRO (1,187 kg of fuel hydrazine of 2,180 kg = 54.4% to reduce 1.4 KM/sec during the orbit insertion.) I have not found how the Venus Express will insert into the Venus. At what speed and the what orbit will be traveling VE (Polar, some inclination Equatorial).

The panel solar is very small : 5.7 M^2 versus 10 M^2 of MRO. VE will have about 1,100 Watts and MRO around 1,000 Watts of power when these spacecraft are in their orbits. VE uses Lithium-ion batteries and MRO uses Nickel-hydrogen batteries. What is the difference?

Rodolfo

Posted by: um3k Oct 13 2005, 03:03 PM

QUOTE (RNeuhaus @ Oct 13 2005, 10:45 AM)
The panel solar is very small : 5.7 M^2 versus 10 M^2 of MRO. VE will have about 1,100 Watts and MRO around 1,000 Watts of power when these spacecraft are in their orbits. VE uses Lithium-ion batteries and MRO uses Nickel-hydrogen batteries. What is the difference?

Rodolfo
*

I'm no expert, but I would venture to guess that the cause is the spacecrafts' distances from the sun.

Posted by: Rakhir Oct 13 2005, 04:03 PM

QUOTE (RNeuhaus @ Oct 13 2005, 04:45 PM)
The spacecraft Technical details

I have not found how the Venus Express will insert into the Venus.

Rodolfo
*


From http://esamultimedia.esa.int/docs/VENUSEXPRESSLR.pdf

"In April 2006, it will fire its main engine to slow down and counteract the predominant pull of the Sun and of Venus, to be captured into orbit around the planet. A large velocity change is required for the initial capture manoeuvre, which will require the engine to burn for 53 minutes."

Orbit details -> see page 8 of the pdf cool.gif

Posted by: RNeuhaus Oct 13 2005, 04:46 PM

QUOTE (Rakhir @ Oct 13 2005, 11:03 AM)
From http://esamultimedia.esa.int/docs/VENUSEXPRESSLR.pdf

"In April 2006, it will fire its main engine to slow down and counteract the predominant pull of the Sun and of Venus, to be captured into orbit around the planet. A large velocity change is required for the initial capture manoeuvre, which will require the engine to burn for 53 minutes."

Orbit details -> see page 8 of the pdf cool.gif
*

Thanks Rakhir, Regrettable, this link needs some kind of authorization.

Forbidden

Your request cannot be serviced due to access restrictions. Please contact your System Administrator for further details

ERROR: your request cannot be serviced

Rodolfo

Posted by: tedstryk Oct 13 2005, 05:06 PM

QUOTE (RNeuhaus @ Oct 13 2005, 04:46 PM)
Thanks Rakhir, Regrettable, this link needs some kind of authorization.

Forbidden

Your request cannot be serviced due to access restrictions. Please contact your System Administrator for further details

ERROR: your request cannot be serviced

Rodolfo
*


Works just fine for me.

Posted by: ugordan Oct 13 2005, 05:09 PM

QUOTE (RNeuhaus @ Oct 13 2005, 06:46 PM)
Thanks Rakhir, Regrettable, this link needs some kind of authorization.

Forbidden

Your request cannot be serviced due to access restrictions. Please contact your System Administrator for further details

ERROR: your request cannot be serviced

Rodolfo
*


I had no problems accessing the pdf just now. Did you try opening the link with a different browser or anything?
I don't know if uploading the document is allowed here due to copyright restrictions?

Posted by: RNeuhaus Oct 13 2005, 06:25 PM

The problem was already solved by changing the proxy IP Address.

Thanks,

Rodolfo

Posted by: Jeff7 Oct 14 2005, 04:22 AM

QUOTE (um3k @ Oct 13 2005, 10:03 AM)
I'm no expert, but I would venture to guess that the cause is the spacecrafts' distances from the sun.
*

I think the part in question was the composition of the batteries - lithium ion vs nickel hydrogen.
I know about li-ion, but I don't know a lot about nickel-hydrogen. I think Hubble also uses the latter type.

Posted by: helvick Oct 14 2005, 08:15 AM

QUOTE (Jeff7 @ Oct 14 2005, 05:22 AM)
I think the part in question was the composition of the batteries - lithium ion vs nickel hydrogen.
I know about li-ion, but I don't know a lot about nickel-hydrogen. I think Hubble also uses the latter type.
*


Li-Ion has better power density but the varous Nickel Hydrogen designs, like the NimH used on some laptops and other consumer electronics kit, has much better charge cycle lifetime. Li-Ion is generally good for up to 1000 charge cycles while there are Ni H designs that are spec'ed out for 30000. NimH batteries also have the benefit of being able to be re-conditioned however I don't know if the process is suitable for use "in flight" with the pressurised NiH type batteries used on spacecraft. Li-Ion degradation is more or less permanent.

There are many other considerations though so the cycling capability is only one possible reason.

Posted by: Rakhir Oct 14 2005, 08:23 AM

QUOTE (um3k @ Oct 13 2005, 05:03 PM)
I'm no expert, but I would venture to guess that the cause is the spacecrafts' distances from the sun.
*


From the pdf of my previous post : "The sun is twice as strong at Venus as on Earth, so there is plentiful solar radiation to power the spacecraft. VE's solar arrays could therefore be made smaller (almost half the size) than those on Mars Express."

Posted by: RNeuhaus Oct 14 2005, 03:59 PM

QUOTE (Jeff7 @ Oct 13 2005, 11:22 PM)
I think the part in question was the composition of the batteries - lithium ion vs nickel hydrogen.
I know about li-ion, but I don't know a lot about nickel-hydrogen. I think Hubble also uses the latter type.
*

I didn't mention well in my last post. You posted is what I was asking about this: What are the differences between the two different types of batteries?

Rodolfo

Posted by: RNeuhaus Oct 14 2005, 04:22 PM

According to the VE's pdf document, VE has greater challenge to orbit around Venus than Mars Express since it has two great concern that must be adjusted continuously:

1) The thrusters has to adjust to correct the altitude of orbit's pericentre approximately once every day. In fact, due to the gravitational pull of the Sun while the spacecraft is further away from the planet, the pericentre naturally drifts upwards at a rate of about 1.5 kilometres per day.

2) For a spacecraft in orbit around Venus, it is not always possible to point a single
antenna dish at Earth while always keeping the cold face of the spacecraft, hosting
delicate instruments, away from the Sun.To overcome this pointing constraint,Venus
Express has two high-gain antennas mounted on different spacecraft faces.The
main high-gain antenna, used for most of the communications with Earth, is a 1.3
metre-diameter dish.The second, smaller high-gain antenna (30 centimetres
diameter) is used when the spacecraft is in the part of its orbit closest to Earth (less
than 0.78 AU* away).

On the other hand:

I have a doubt about the VE's trajectory to Venus. Will the Soyus-Fraget travel in the opposite way to the Earth's rotation before going to Venus?

I tought it since the Earth position is on the apehelion comparing to the Venus position as perihelion. Hence, the trajectory from Earth to Venus is of inward bound. To launch a spacecraft from Earth to an inner planet such as Venus using least propellant, its existing solar orbit (as it sits on the launch pad) must be adjusted so that it will take it to Venus. In other words, the spacecraft's aphelion is already the distance of Earth's orbit, and the perihelion will be on the orbit of Venus.

This time, the task is to decrease the periapsis (perihelion) of the spacecraft's present solar orbit. A spacecraft's periapsis altitude can be lowered by decreasing the spacecraft's energy at apoapsis. To achieve this, the spacecraft lifts off of the launch pad, rises above Earth's atmosphere, and uses its rocket to accelerate opposite the direction of Earth's revolution around the sun, thereby decreasing its orbital energy while here at apoapsis (aphelion) to the extent that its new orbit will have a perihelion equal to the distance of Venus's orbit. Of course the spacecraft will continue going in the same direction as Earth orbits the sun, but a little slower now. To get to Venus, rather than just to its orbit, again requires that the spacecraft be inserted into its interplanetary trajectory at the correct time so it will arrive at the Venusian orbit when Venus is there. Venus launch opportunities occur about every 19 months.



Will do VE follow the trajectory of least energy orbit as mentioned above?

Rodolfo

Posted by: dvandorn Oct 15 2005, 08:59 AM

Your diagram shows the most common Hohmann transfer orbit, achieved by reducing the aphelion to coincide with the orbit of Venus (preferably when Venus itself is occupying that point along its own orbit).

There is another type of Hohmann trajectory for this type of mission. Instead of braking against the Earth's solar orbital velocity, the spacecraft thrusts at right angles to Earth's near-circular orbit (likely directly towards the Sun), creating a lopsided orbit with a perihelion at Venus and an aphelion well outside of Earth's orbit. The good thing is that the average orbital velocity of such an orbit is very nearly the same as the Earth's velocity, so you don't need to brake so much. The bad thing is that it takes even more energy to enter this transfer orbit, and your approach speed at Venus is somewhat higher, requiring more energy to brake you into orbit.

It gets you there a little faster than the brake-against-solar-orbit method, but it takes more energy.

-the other Doug

Posted by: Rakhir Oct 17 2005, 08:25 PM

Fairing Installation

Today, Monday 17 October 2005, the payload fairing has been successfully installed on the nose block (composite of Fregat Upper Stage and Venus Express spacecraft). The first part of the activity was the tilting of the nose block from vertical to horizontal position. With both the spacecraft and the Upper Stage being fully fuelled the activity is classified as hazardous, and was hence conducted with the minimum number of personnel present in the clean room.

8 days...

The update including some images of the operation :
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38153

Posted by: RNeuhaus Oct 19 2005, 10:30 PM

New updates about Venus Express. More details about the magnetometer instrument.

http://www.spacedaily.com/news/venus-05g.html

Rodolfo

Posted by: Rakhir Oct 21 2005, 11:03 AM

New ESA update : summary of the launch, cruise and arrival phases.

http://www.esa.int/esaCP/SEM0U7R01FE_index_0.html

Rakhir

Posted by: Adam Oct 21 2005, 06:31 PM

Delayed:

http://www.esa.int/esaCP/SEM0CV3J2FE_index_0.html

Posted by: Rakhir Oct 25 2005, 11:33 AM

Venus Express preliminary investigations bring encouraging news.

"On Monday 24 October the fairing was removed and engineers started the inspection to assess the status of the spacecraft.
The scenario is so far very encouraging, as only fairly large particles, pieces of the insulating material initially covering the launcher’s Fregat upper stage, have been found on the body of the spacecraft.
The ESA Project team is confident that Venus Express will be launched well within the launch window, which closes on 24 November this year."

http://www.esa.int/esaCP/SEM2714J2FE_index_0.html

Rakhir

Posted by: SigurRosFan Oct 26 2005, 01:27 PM

Spaceflightnow Mission Status Center: Venus Express

http://spaceflightnow.com/venusexpress/status.html

--- Although a new launch date has not been set, liftoff is expected to be targeted for sometime between November 6 and 9. ---

Posted by: Rakhir Oct 31 2005, 05:21 PM

Russian space officials Monday set a Nov. 9 blastoff.

http://www.space.com/missionlaunches/ap_051031_venusexp_updt.html

Rakhir

Posted by: RNeuhaus Oct 31 2005, 09:23 PM

Strange news.

The postpone of the launch was due to contamination problem in the faring. Now, according to the news from space.com :

Russian space officials Monday set a Nov. 9 blastoff for a European probe to explore Venus after its earlier launch was postponed because of a booster rocket problem.

Is it of another story?

Rodolfo

Posted by: Rakhir Oct 31 2005, 10:24 PM

QUOTE (RNeuhaus @ Oct 31 2005, 11:23 PM)
Strange news.

The postpone of the launch was due to contamination problem in the faring. Now, according to the news from space.com :

Russian space officials Monday set a Nov. 9 blastoff for a European probe to explore Venus after its earlier launch was postponed because of a booster rocket problem.

Is it of another story?

Rodolfo
*


By "booster rocket", they are talking about the launch vehicle. The fairing whose thermal insulation contaminated VE is part of the booster rocket.

Rakhir

Posted by: Rakhir Nov 5 2005, 04:42 PM

Roll Out to Launch Pad

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38214

Rakhir

Posted by: Rakhir Nov 6 2005, 11:24 PM

Pre-launch sequence was executed.
2 days...

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38218

Rakhir

Posted by: paulanderson Nov 7 2005, 01:35 AM

Interesting article:

'Venus Mission May Hold Surprises For Scientists And Public, Says CU Prof'
http://www.colorado.edu/news/releases/2005/421.html

Posted by: mike Nov 7 2005, 03:04 AM

If Venus is almost exactly like Earth, but much hotter, and Mars is quite a lot like Earth, but much cooler, and Venus is closer to the sun than Earth, and Mars is further away from the sun than Earth, then hmm, what could it be I wonder... smile.gif

I'm looking forward to this mission myself..

Posted by: JRehling Nov 7 2005, 03:41 PM

QUOTE (mike @ Nov 6 2005, 08:04 PM)
If Venus is almost exactly like Earth, but much hotter, and Mars is quite a lot like Earth, but much cooler, and Venus is closer to the sun than Earth, and Mars is further away from the sun than Earth, then hmm, what could it be I wonder...  smile.gif

I'm looking forward to this mission myself..
*


Mars is only about 11% the mass of the Earth, and the bulk composition is quite different, so the differences abound. Given that and other differences that began with formation, I'd say differences should be expected as the rule and similarities seen as more surprising.

Venus has similar mass and bulk composition, but the essential cause-of-it-all difference maker may be the slow rotation. Because of that, no magnetic field. Because of that, the upper atmosphere is pounded by solar wind. Because of that, H2O is broken up and lost. Because of that, CO2 fills the atmosphere AND lighter rock (granite) is not formed. Because of the CO2, the stifling heat. Because of the lack of granite and the heat, entirely different crustal cycling regimes.

It's unclear if that is really the chain of causality, and certainly more exploration is needed, but it would be stirring if such a small matter led to such a huge difference. And it would still be unclear why the rotation is so slow; there is a chicken-and-egg question about whether or not drag in the massive atmosphere may have controlled the rotation rate. The other external factor that may have contributed is the absence of a large satellite.

Posted by: RNeuhaus Nov 7 2005, 03:54 PM

Besides, the other intrigating thing is that Venus sluggishly rotates on its axis once every 243 Earth days, while it orbits the Sun every 225 days - its day is longer than its year!

On the other hand, Venus rotates retrograde, or "backwards," spinning in the opposite direction of its orbit around the Sun. From its surface, the Sun would seem to rise in the west and set in the east.

The other odd thing is that its Equatorial Inclination to Orbit is 177.3 degrees. By comparison, it is: 7.56 x Earth. That is its north pole is almost pointing to the south pole.

These are at least one of the oddies things that I would like to understand:

Why does the day is longer than a year?
Why the planet rotates on backwards?

Rodolfo

Posted by: ljk4-1 Nov 7 2005, 04:03 PM

QUOTE (RNeuhaus @ Nov 7 2005, 10:54 AM)
Besides, the other intrigating thing is that Venus sluggishly rotates on its axis once every 243 Earth days, while it orbits the Sun every 225 days - its day is longer than its year!

On the other hand, Venus rotates retrograde, or "backwards," spinning in the opposite direction of its orbit around the Sun. From its surface, the Sun would seem to rise in the west and set in the east.

The other odd thing is that its Equatorial Inclination to Orbit is 177.3 degrees. By comparison, it is: 7.56 x Earth. That is its north pole is almost pointing to the south pole.

These are at least one of the oddies things that I would like to understand:

Why does the day is longer than a year?
Why the planet rotates on backwards?

Rodolfo
*


A whomping big celestial impact is my guess.

Posted by: RNeuhaus Nov 7 2005, 04:26 PM

QUOTE (ljk4-1 @ Nov 7 2005, 11:03 AM)
A whomping big celestial impact is my guess.
*

Interesting but...why no a moon. After an impact to Venus and that should have a moon like the Earth's case.

I thought that the Venus' slow rotation might be caused by a very heavy atmosphere that circulates the planet in the opposite side to its rotation.

Or perhaps that is a normal for physics' law since its neigboor planet Mercury rotates around 58 Earth days and orbits around the Sun 88 Earth days. That is more or less a very long day that approach to a "planet of close one year" for both Mercury (less days) and Venus (more days).

Rodolfo

Posted by: ljk4-1 Nov 7 2005, 04:30 PM

QUOTE (RNeuhaus @ Nov 7 2005, 11:26 AM)
Interesting but...why no a moon. After an impact to Venus and that should have a moon like the Earth's case.

I thought that the Venus' slow rotation might be caused by a very heavy atmosphere that  circulates the planet in the opposite side to its rotation.

Or perhaps that is a normal for physics' law since its neigboor planet Mercury rotates around 58 Earth days and orbits around the Sun 88 Earth days.  That is more or less a very long day that approach to a "planet of close one year" for both Mercury (less days) and Venus (more days).

Rodolfo
*


Actually, should a large impact create a moon? My guess is that if Venus did get hit by something massive and powerful enough to practically flip it over, slow down its spin rate, and have it rotate in the opposite direction of most other major worlds, Venus was lucky enough to have survived intact, forget having a moon in the outcome.

Or maybe Venus was hit BY its own moon.

Posted by: djellison Nov 7 2005, 04:57 PM

Moons tend to orbit their parent planet in the same direction as the planets rotation - so were a moon to colide with its parent planet, the likely impact would be an increase in rotation I'd have thought.

Perhaps it's a symptom of planet formation closer to the centre of the protoplanetary disk - further out from the sun, the local gravity from chunks of whatever is the major force, but closer in, the suns gravity is dominant.

It's a complex process, that's for sure.


Doug

Posted by: JRehling Nov 7 2005, 05:26 PM

QUOTE (ljk4-1 @ Nov 7 2005, 09:30 AM)
Actually, should a large impact create a moon?  My guess is that if Venus did get hit by something massive and powerful enough to practically flip it over, slow down its spin rate, and have it rotate in the opposite direction of most other major worlds, Venus was lucky enough to have survived intact, forget having a moon in the outcome.

Or maybe Venus was hit BY its own moon.
*


There are good sources on the Net for things being wildly speculated about here.

To pick just one: the angular momentum of a planet-moon system would remain the same after an impact as before. Such a collision couldn't make the system go backwards unless it was going backwards in the first place.

For the Moon to be created from a collision, it had to be a glancing blow. A straight-on punch would not liberate a lot of material.

A collision would be necessary if Venus's rotation was set in place as its formation concluded. But there are suggestions that tidal and thermal dynamics of its massive atmosphere may have "set" the rotation at the current rate. If so, the initial rotation is irrelevant/unknowable. In fact, the low inclination suggests that there is some sort of sun-driven factor: a collision that reordered Venus's rotation radically would be unlikely to leave the axis so nearly perpendicular to its orbit -- although that kind of coincidence is not impossible.

The rotation is only one oddity, not two or more. Given that the rotation is so slow, the reversal is not so odd -- the difference between rotating slowly E-W or slowly W-E is not nearly so big a difference as the slow rotation in the first place. Consider that a point on Venus's equator is rotating at about the speed of a fast *walk*!!! If it were moving the other direction, but just as slowly, that would only be a difference of a few km/h.

Also, the relative relationship between the day and year of Venus is not an "extra" oddity. Given the slow rotation, that follows as a logical consequence.

There is a second mystery regarding Venus's rotation, however, and that is why it is [almost] synchronized so as to show [almost] the same face towards the Earth at every conjunction. Mathematically, it would seem impossible for the tidal attraction to make this happen... but if this is a coincidence, it is a remarkable one.

Posted by: The Messenger Nov 7 2005, 05:46 PM

QUOTE (JRehling @ Nov 7 2005, 10:26 AM)
There is a second mystery regarding Venus's rotation, however, and that is why it is [almost] synchronized so as to show [almost] the same face towards the Earth at every conjunction. Mathematically, it would seem impossible for the tidal attraction to make this happen... but if this is a coincidence, it is a remarkable one.
*


I'm filing this gem right next to the thermal energy in the Tiger stripes of Enceladus.

One thing is clear: The Solar System loves to throw us curve balls.

Posted by: BruceMoomaw Nov 7 2005, 09:20 PM

Well, as Chesterton said, the most remarkable thing about coincidences is that occasionally they DO occur. The classic one in the Solar System is the disks of the Moon and Sun being virtually the same size as seen from Earth, which is the only thing that makes solar eclipses as we know them possible.

The trouble comes when the fact that the human (and presumably animal) mind is designed to specifically look for patterns leads us to jump to the conclusion that a genuine coincidence is more than that. Arthur Koestler once wrote an infamous crank philosophical book based on precisely that logical fallacy.

Posted by: RNeuhaus Nov 7 2005, 09:57 PM

Anyway, at the beginning of the planetary formation, all planets is formed orbiting around the sun in the counter-clockwise, all have the same plane inclination with respect to the sun, all planets has their axis in perpendicular position to the planetary plane and all rotate the same way as it is orbiting around the sun, it is counter-clockwise.

are those all above suppositions affirmative or not?

Rodolfo

Posted by: ljk4-1 Nov 7 2005, 10:08 PM

QUOTE (JRehling @ Nov 7 2005, 12:26 PM)
There are good sources on the Net for things being wildly speculated about here.

*


There was this guy a long time ago named Aristarchus who wildly speculated that Earth went around the Sun and that the stars were other suns very far away.

The powers that be of his era accused him of religious impiety. His ideas were effectively buried for 1,500 years.

These ideas may "just" be speculation, but they are not wild. Uranus has been thought by many sober, rational astronomers to be in its present state due to major collisions by natural objects in its past, so why not for Venus to explain its current different state?

Posted by: imran Nov 9 2005, 02:41 AM

Less than one hour from launch!

Live webcast should be here:
http://www.starsem.com

Posted by: Waspie_Dwarf Nov 9 2005, 03:06 AM

Alternative link for the live webcast of the launch: http://www.esa.int/SPECIALS/Venus_Express/SEMHZY538FE_0.html

Posted by: jamescanvin Nov 9 2005, 03:11 AM

QUOTE (imran @ Nov 9 2005, 01:41 PM)
Less than one hour from launch!

Live webcast should be here:
http://www.starsem.com
*


Anybody getting a feed from here yet?

Just wondering if the error message I'm getting is because it hasn't starting or if there is an incompatibilty with the OSX version of Media Player.

James

Posted by: Waspie_Dwarf Nov 9 2005, 03:14 AM

The live feed won't start until 03:28 GMT, at least on the ESA site. I assume it is the same on the Starsem site.

Posted by: jamescanvin Nov 9 2005, 03:14 AM

QUOTE (Waspie_Dwarf @ Nov 9 2005, 02:06 PM)
Alternative link for the live webcast of the launch: http://www.esa.int/SPECIALS/Venus_Express/SEMHZY538FE_0.html
*


Ah, cross posting, a much more useful site.smile.gif

Starts only 5 mins before launch...

Posted by: imran Nov 9 2005, 03:22 AM

Both webcasts are working now although you get better resolution from the Starsem site.

Posted by: imran Nov 9 2005, 03:30 AM

0327 GMT (10:27 p.m. EDT Tues.)

The Venus Express flight director in mission control has given the final "go" for launch.

Posted by: imran Nov 9 2005, 03:32 AM

QUOTE (imran @ Nov 9 2005, 03:30 AM)
0327 GMT (10:27 p.m. EDT Tues.)

The Venus Express flight director in mission control has given the final "go" for launch.
*


T - 40 seconds!!

Posted by: jamescanvin Nov 9 2005, 03:33 AM

QUOTE (imran @ Nov 9 2005, 02:22 PM)
Both webcasts are working now although you get better resolution from the Starsem site.
*


Starsem still doesn't work for me bu thankfully the ESA feed does smile.gif (thanks Waspie_Dwarf!)

Posted by: imran Nov 9 2005, 03:33 AM

QUOTE (jamescanvin @ Nov 9 2005, 03:33 AM)
Starsem still doesn't work for me bu thankfully the ESA feed does  smile.gif  (thanks Waspie_Dwarf!)
*


LIFTOFF!!!!

Posted by: jamescanvin Nov 9 2005, 03:38 AM

QUOTE (imran @ Nov 9 2005, 02:33 PM)
LIFTOFF!!!!
*


OK through booster sep...

Posted by: imran Nov 9 2005, 03:38 AM

0336 GMT (10:36 p.m. EDT Tues.)

T+plus 3 minutes. The first stage strap-on boosters have been jettisoned. The second stage core is still running as planned. All system parameters are reported normal.

Posted by: jamescanvin Nov 9 2005, 03:39 AM

QUOTE (jamescanvin @ Nov 9 2005, 02:38 PM)
OK through booster sep...
*


Fairing sep, third stage ignition...

Posted by: imran Nov 9 2005, 03:41 AM

Cutoff of 3rd stage and separation of nose module.

Posted by: jamescanvin Nov 9 2005, 03:42 AM

QUOTE (imran @ Nov 9 2005, 02:41 PM)
"Everything is nominal"
*


Third stage cutoff!

Posted by: imran Nov 9 2005, 03:43 AM

QUOTE (jamescanvin @ Nov 9 2005, 03:42 AM)
Third stage cutoff!
*


0342 GMT (10:42 p.m. EDT Tues.)

T+plus 9 minutes. The third stage motor has completed its firing and dropped away. The Fregat upper stage now must perform a brief firing to achieve an initial parking orbit around Earth.

Posted by: imran Nov 9 2005, 03:46 AM

There goes the feed. Oh well..guess I'll have to rely on the Spaceflightnow updates.

Posted by: imran Nov 9 2005, 03:51 AM

0348 GMT (10:48 p.m. EDT Tues.)

T+plus 15 minutes. ESA says the first Fregat burn has been successful. The vehicle is now coasting in Earth orbit for more than an hour before the upper stage is re-started to propel the spacecraft to Venus.

Posted by: elakdawalla Nov 9 2005, 05:02 AM

Argh! Is that second Fregat burn happening or not?

Posted by: jamescanvin Nov 9 2005, 05:06 AM

Fregat burn should be underway by now.

No word on Spaceflightnow yet...

EDIT: cross posting with you Emily. I feel your pain, I don't know how much more page reloads my computer (and me) can take!

Posted by: jamescanvin Nov 9 2005, 05:16 AM

From Spaceflightnow.com

0514 GMT (12:14 a.m. EST)

T+plus 1 hour, 41 minutes. By this point in the flight the Fregat should have completed its burn and then released Venus Express. We're awaiting confirmation from ESA that these events have occurred successfully.

Posted by: Bricktop Nov 9 2005, 05:19 AM

From http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38243

Fregat second stage has successfully fired and place Venus Express to an escape trajectory smile.gif

Posted by: Waspie_Dwarf Nov 9 2005, 05:20 AM

QUOTE (jamescanvin @ Nov 9 2005, 05:16 AM)
From Spaceflightnow.com

0514 GMT (12:14 a.m. EST)

T+plus 1 hour, 41 minutes. By this point in the flight the Fregat should have completed its burn and then released Venus Express. We're awaiting confirmation from ESA that these events have occurred successfully.
*


In other words Spaceflight Now doesn't know if the Fregat has worked either. The anticipation is killing me.

Posted by: Rakhir Nov 9 2005, 05:20 AM

From http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38243

MET: +01h 40m
Fregat second stage has successfully fired and place Venus Express to an escape trajectory biggrin.gif

Rakhir

EDIT : You were 1 min quicker than me Bricktop.

Posted by: Waspie_Dwarf Nov 9 2005, 05:22 AM

QUOTE (Bricktop @ Nov 9 2005, 05:19 AM)
From http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38243

Fregat second stage has successfully fired and place Venus Express to an escape trajectory  smile.gif
*


That's put me out of my misery. smile.gif

Posted by: jamescanvin Nov 9 2005, 05:25 AM

Hurrrah!

Venus here we come smile.gif

Posted by: elakdawalla Nov 9 2005, 05:48 AM

This from Daniel Fischer: "Just to report that Venus Express has phoned home exactly on time at 5:30 UTC through ESA's ground station in New Norcia, Western Australia! Everything seems to be going exactly to plan since 2 hours. Now it's about 3 weeks of spacecraft and instrument checkout; perhaps some nice pictures of Earth will be taken during that period (as ESA's Gerhard Schwehm just told me). Then it's quiet cruising (no science on the way), until Venus Orbit Insertion on April 11, 2006."

Posted by: JRehling Nov 9 2005, 06:12 AM

QUOTE (ljk4-1 @ Nov 7 2005, 03:08 PM)
There was this guy a long time ago named Aristarchus who wildly speculated that Earth went around the Sun and that the stars were other suns very far away.

The powers that be of his era accused him of religious impiety.  His ideas were effectively buried for 1,500 years.

These ideas may "just" be speculation, but they are not wild.  Uranus has been thought by many sober, rational astronomers to be in its present state due to major collisions by natural objects in its past, so why not for Venus to explain its current different state?
*


What I meant was, sometimes the answer is in the FAQ. smile.gif

Posted by: Rakhir Nov 9 2005, 06:17 AM

MET: +02h 40m
Sun acquisiton and successfully deployment of solar arrays confirmed smile.gif

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38243

Rakhir

Posted by: Decepticon Nov 9 2005, 07:03 AM

QUOTE
Venus Orbit Insertion on April 11, 2006."



And Public won't see any data till August.


Ya ya I know I'm bad. tongue.gif

Posted by: edstrick Nov 9 2005, 07:06 AM

"Sun acquisiton and successfully deployment of solar arrays confirmed "

------------------ YEEEEHAAWWWWWW! ------------------------------------

Chances of "Loss-of-Mission" have dropped by some 85%

Posted by: remcook Nov 9 2005, 10:03 AM

well...there's still orbit insertion.
but hopefully that will all go well. in the meantime: hooray!

Posted by: edstrick Nov 9 2005, 10:32 AM

"....well...there's still orbit insertion...."

Mars Observer, lost during orbit insertion preparation.
Mars Climate Orbiter, lost in atmosphere during unsurvivable accidental areo-CAPTURE attempt.
Mars-4 and Nozomi both could not attempt orbit insertion burn.

85% is probably a fair arm-waving assessment of the risk fraction for an orbiter mission.

Posted by: Rakhir Nov 9 2005, 12:16 PM

- First star tracker switched on.
- Reaction wheels switched on.
- Venus Express achieved Normal Mode indicating full 3 axis stabilised conditions and full control through ground operations.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38250

Rakhir

Posted by: RNeuhaus Nov 9 2005, 03:01 PM

QUOTE (JRehling @ Nov 9 2005, 01:12 AM)
What I meant was, sometimes the answer is in the FAQ.    smile.gif
*

Maybe, nobody will be able to answer it for forever....! That is a big question that its original axis has turned down or maybe it started so on the contrary to the rest of planets.

Rodolfo

Posted by: The Messenger Nov 9 2005, 04:17 PM

QUOTE (edstrick @ Nov 9 2005, 03:32 AM)
"....well...there's still orbit insertion...."

Mars Observer, lost during orbit insertion preparation.
Mars Climate Orbiter, lost in atmosphere during unsurvivable accidental areo-CAPTURE attempt.
Mars-4 and  Nozomi both could not attempt orbit insertion burn.

85% is probably a fair arm-waving assessment of the risk fraction for an orbiter mission.
*


The upper atmosphere of Venus SEEMS to be less fickle, and there is a little less mission time delay - so there are some minor odds movers. The big intangable is solar flare-ups - some of those burps look like they could eat Messinger or Express.

Posted by: Rakhir Nov 9 2005, 05:38 PM

QUOTE (The Messenger @ Nov 9 2005, 06:17 PM)
The upper atmosphere of Venus SEEMS to be less fickle.
*


Anyway, the atmosphere should not be a problem because VE will not use aero-capture... unless a huge navigational error or unit of measure conversion error like it was for MCO rolleyes.gif

Rakhir

Posted by: JRehling Nov 9 2005, 05:39 PM

QUOTE (Decepticon @ Nov 9 2005, 12:03 AM)
And Public won't see any data till August.
Ya  ya I know I'm bad. tongue.gif
*


But ESA will claim important new discoveries sooner than that.

It's sad, but my elation over the purpose of the mission is so moderated by the fact that it's ESA doing the data release. I think we just need to psychologically prepare ourselves as though this were a 2008 mission and be happy to see the results trickle in eventually.

Posted by: BruceMoomaw Nov 10 2005, 12:36 AM

Venus' upper atmosphere is MUCH more stable, density-wise, than Mars' -- simply because Mars' total atmosphere is so thin that the heating from dust storms can cause the atmosphere as a whole to dramatically warm, and thus balloon upwards in Mars' weak gravity. In fact, it was stated by a speaker at the COMPLEX meeting that this is the one piece of new environmental engineering measurements we absolutely MUST have for near-future Mars missions even of the unmanned variety: a satellite to monitor Martian weather and its correlation with upper-atmospheric density fluctuations in much more detail than has yet been done. We came within a hair of losing the Spirit rover even BEFORE it also ran into those high-speed near-surface winds (which, by the way, are less important for a throttled-rocket soft lander), because Mars' upper air density was 10% less than even the worst-case prediction based on obsevations the week before the landing, and so the vehicle was braked much less during entry than expected.

Posted by: Sedna Nov 10 2005, 12:38 AM

QUOTE (JRehling @ Nov 9 2005, 07:39 PM)
But ESA will claim important new discoveries sooner than that.

It's sad, but my elation over the purpose of the mission is so moderated by the fact that it's ESA doing the data release. I think we just need to psychologically prepare ourselves as though this were a 2008 mission and be happy to see the results trickle in eventually.
*


Are you meaning that ESA's data policy is not the right one? Maybe JAXA's is better...

Posted by: The Messenger Nov 10 2005, 01:43 AM

QUOTE (BruceMoomaw @ Nov 9 2005, 05:36 PM)
We came within a hair of losing the Spirit rover even BEFORE it also ran into those high-speed near-surface winds (which, by the way, are less important for a throttled-rocket soft lander), because Mars' upper air density was 10% less than even the worst-case prediction based on obsevations the week before the landing, and so the vehicle was braked much less during entry than expected.
*

Where do you get all this stuff? I have been looking for the descent profiles for Spirit and Opportunity for a year now!

Posted by: djellison Nov 10 2005, 09:48 AM

QUOTE (Sedna @ Nov 10 2005, 12:38 AM)
Are you meaning that ESA's data policy is not the right one?


It's certainly not good enough - that is without doubt.

Doug

Posted by: tedstryk Nov 10 2005, 10:39 AM

I am looking forward to the great discovery of the fact that the visible imaging channels can't see through to the surface.

Posted by: BruceMoomaw Nov 10 2005, 12:53 PM

QUOTE (The Messenger @ Nov 10 2005, 01:43 AM)
Where do you get all this stuff? I have been looking for the descent profiles for Spirit and Opportunity for a year now!
*


I got that from Jay Bergstralh's talk on the problem at COMPLEX -- but there have been some notes scattered around previously on the Web on the subject, though I'd have to track them down. (Bergstralh obligingly included a graph, which I'd never seen before, of the precise degree to which MER-A's air-density readings were below the 12-27-03 estimate -- the zone giving most of the trouble was 20-50 km, and at one point the density was fully 12% below the worst-case prediction. MER-A came down so much faster than predicted that had it popped its chute 3 seconds later, it would have crashed.)

Posted by: djellison Nov 10 2005, 01:41 PM

The EDL data is on the PDS - but it's a bit awkward to use - the derived stuff is in there, I'll see if I can put Pathfinder, Spirit and Oppy pressure profiles together.

Doug

Posted by: The Messenger Nov 10 2005, 04:04 PM

QUOTE (djellison @ Nov 10 2005, 06:41 AM)
The EDL data is on the PDS - but it's a bit awkward to use - the derived stuff is in there, I'll see if I can put Pathfinder, Spirit and Oppy pressure profiles together.

Doug
*

Thanks Bruce and Doug - I guess I need to bite the bullet and figure out how to extract from the PDS, but doesn't look friendly, and it would be easy to spend days, and still not have confidence I had extracted the right data.

I'm looking forward to the day when the ESA is sitting on so much embargoed data, that they loose track of the release dates and open the floodgates. An ESA-PDS?

Posted by: djellison Nov 10 2005, 04:41 PM

Well MEX stuff is already in the PDS, and ESA opperate their own pseudo-PDS-tool at http://www.rssd.esa.int/index.php?project=PSA - problem being, due to the nature of HRSC data, it's basically impossible to use

Doug

Posted by: Sedna Nov 10 2005, 11:05 PM

QUOTE (djellison @ Nov 10 2005, 11:48 AM)
It's certainly not good enough - that is without doubt.

Doug
*


Spacecrafts are flying labs, not handy cameras to take snapshots to be shown worldwide on the run... Data have to be received, processed, verified... That's not so spectacular as NASA's rovers landing on Mars, for instance, but that's what science is... B.T.W., Huygens lander's policy was not very different to Spirit's or Opportunity's...

Posted by: djellison Nov 10 2005, 11:22 PM

QUOTE (Sedna @ Nov 10 2005, 11:05 PM)
Spacecrafts are flying labs, not handy cameras to take snapshots to be shown worldwide on the run... Data have to be received, processed, verified... That's not so spectacular as NASA's rovers landing on Mars, for instance, but that's what science is... B.T.W., Huygens lander's policy was not very different to Spirit's or Opportunity's...
*


I know all of that, more than well enough.

The Huygens policy is very different to the rovers. We are almost 12 months from landing, and the full instrument data set is not online. If it were MER, it would have been online for 6 months already.

MSSS and Themis team offer a useable, intuitive interface for Mars Orbiter data, the MEX HRSC data is almost unuseable and barely accesable.

ESA press releases are infrequent, inaccurate and often make idiotic claims that are untrue and unfounded.

It's not just an image releasing strategy that ESA lacks by a long long way

Doug

Posted by: mike Nov 10 2005, 11:28 PM

While I agree that the ESA press releases can be exaggerated (infinitely more data?), I can't blame them for wanting to hold onto the data for a while. Nobody has landed anything on Titan before, and as Europe hasn't had much of a space program compared to the US I'm sure they want to impress as much as possible.

Personally, I'm happy with the images they've released thus far. I think that once the ESA has something definitive to say regarding the data they'll say it. I can't think of any benefit for them to holding onto the data forever, unless maybe they're just scouting for rare minerals (and they'd lose all credibility in that case).

Posted by: tedstryk Nov 10 2005, 11:28 PM

It seems to me a difference between releasing data because you want people to be able to access it versus releasing it to the public simply because you are being made to.

Posted by: Decepticon Nov 11 2005, 12:34 AM

Any Earth departure images planned?

Posted by: Sedna Nov 11 2005, 12:36 AM

Anyway, I think that there is science on the one hand and marketing on the other...

Posted by: Sedna Nov 11 2005, 12:44 AM

QUOTE (Decepticon @ Nov 11 2005, 02:34 AM)
Any Earth departure images planned?
*


It will take some images, for calibration purposes, but quite far away from the Earth. There are no further scientific activities planned for the cruise phase.

Posted by: Rakhir Nov 11 2005, 08:10 PM

The critical Launch and Early Orbit Phase (LEOP) for Venus Express was completed today.
The spacecraft is performing flawlessly.

Trajectory Correction Manoeuvre (TCM-1) was successfully completed.
The craft is now on the exact trajectory required for Venus Orbit Insertion in five months' time.

With LEOP running so smoothly, controllers were able to bring forward some platform commissioning activities, which were originally planned for the weekend.

With the start of the Near Earth Commissioning Phase, payload activities are due to start on 18 November; these initial switch-on and test activities are scheduled to be complete by 14 December.

http://www.esa.int/SPECIALS/Venus_Express/SEMK9UJBWFE_0.html

Rakhir

Posted by: Rakhir Nov 25 2005, 12:32 PM

Platform Completes near Earth Commissioning.
The remaining testing activities on the platform side will take place in January (thermal characterization) and in February (main engine calibration).

Payload Commissioning Underway : MAG, VIRTIS, and VMC.
During this period the Earth-Moon observation is planned

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38323

Posted by: remcook Nov 26 2005, 11:46 AM

the earth data cubes from VIRTIS look very promising! Imagine seeing all the cloud layers of venus with this! and even the surface! (sorry just being a bit excited smile.gif )

http://www.esa.int/esaCP/SEMOIGULWFE_index_0.html

Posted by: ljk4-1 Dec 22 2005, 03:01 PM

Venus Express - End of Near Earth Commissioning Phase

During the reporting period the last activities of the Near Earth Commissioning
have been completed according to the plan. Two slots with the New Norcia ground
station have been dedicated to test the performance of the TTC subsystem and of
the Ultra Stable Oscillator (USO) for the radio science experiment (VeRA). In
both occasions problems in operating the ground station equipment have affected
the test.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38473

Posted by: ljk4-1 Jan 11 2006, 07:35 PM

VENUS EXPRESS STATUS REPORT

Report for Period 16 December 2005 - 05 January 2006

During the reporting period the spacecraft has been configured for a passive cruise phase and the only activities conducted on top of the routine ones are the DDOR tests with ESA (NNOCEB) and DSN (GDS-CAN) stations.

http://sci.esa.int/jump.cfm?oid=38559

Posted by: RNeuhaus Jan 12 2006, 04:26 PM

At the end of the last NNO pass in the reporting period (DOY 006, 06:00) Venus Express was 15.5 million km from the Earth, 131.7 million km from the Sun, and 25.5 million km from Venus. The one-way signal travel time was 52 seconds.

VE is already above than 38% of distance from Earth.

Future Milestones

The coming week will mark a "close to inferior conjunction" condition, therefore, no major operations are planned. The actual conjunction condition will be reached on DoY 011 at around 18:00 when the angular distance between the Sun and the spacecraft as seen from the Earth will be approximately 1.6 degrees. No significant impact is foreseen on the RF link.


http://www.spacedaily.com/news/Venus_Express_Passive_Cruise_Phase_Begins.html

Rodolfo

Posted by: Rakhir Jan 24 2006, 04:12 PM

An interesting milestone today : We are at the halfway point of the 153 days cruise phase.

And it's already a couple of days that VE is closer from Venus than from Earth. smile.gif

On January 19th, Venus Express was 21.9 million km from the Earth and 19.2 million km from Venus.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38648

Rakhir

Posted by: ljk4-1 Feb 10 2006, 01:40 PM

Venus Express articles in ESA Bulletin Number 124 online here:

http://www.esa.int/SPECIALS/ESA_Publications/SEMW3IMZCIE_0.html

Contents

Venus Express: The Mission Begins

The Venus Express Mission
Donald McCoy, Thorsten Siwitza & Roy Gouka

Venus Express: The Spacecraft
Alistair J. Winton et al.

The Science Return from Venus Express
Håkan Svedhem, Olivier Witasse & Dmitri V. Titov

Venus Express Ground Segment and Mission Operations
Manfred Warhaut & Andrea Accomazzo

ESA’s New Cebreros Station Ready to Support Venus Express
Manfred Warhaut, Rolf Martin & Valeriano Claros

The Roadmap for a GMES Operational Oceanography Mission
Mark Drinkwater et al.

A Tsunami Early-Warning System
– The Paris Concept
Manuel Martin-Neira & Christopher Buck

EGNOS Operations and Their Planned Evolution
Laurent Gauthier et. al.

The BGAN Extension Programme
Juan J. Rivera, Eyal Trachtman & Madhavendra Richharia

Subscribe to the printed version of the ESA Bulletin free of charge. Visit our Bookshop for ordering information.

Posted by: stevo Feb 10 2006, 06:31 PM

Thanks, this is really interesting background.
But the pedant in me can’t help but quibble at the following quote from the Venus Express Mission section:

“… surface temperatures reach 470C (about ten times higher than the hottest temperature on Earth), “

I know it’s outreach and all, but that’s simply wrong, conceptually wrong. 470C (~740K) is about 2.5 times Earth surface temperature.

Posted by: BruceMoomaw Feb 11 2006, 02:20 AM

It's about 10 times higher above FREEZING than the highest temperatures on Earth, which presumably is what they meant to say.

Posted by: Rakhir Feb 13 2006, 11:54 AM

Continued Spacecraft Testing
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38746

During next week the Main Engine pressurisation and calibration will take place.
After the Main Engine burn, an eventual correction will be done one week later.

Posted by: Rakhir Feb 17 2006, 04:56 PM

Successful Venus Express main engine test
http://www.esa.int/esaCP/SEMVX5MVGJE_index_0.html

One hundred days after beginning its cruise to Venus, ESA’s Venus Express spacecraft successfully tested its main engine for the first time in space.

Posted by: ljk4-1 Feb 17 2006, 06:56 PM

QUOTE (Rakhir @ Feb 17 2006, 11:56 AM) *
Successful Venus Express main engine test
http://www.esa.int/esaCP/SEMVX5MVGJE_index_0.html

One hundred days after beginning its cruise to Venus, ESA’s Venus Express spacecraft successfully tested its main engine for the first time in space.


-- Venus Express Status Report: Continued Spacecraft Testing

http://www.spaceref.com/news/viewsr.html?pid=19665

-- Venus Express Status Report: Start of Second Payload Pointing Campaign

http://www.spaceref.com/news/viewsr.html?pid=19664

-- Venus Express Status Report: Main Engine Calibration Test

http://www.spaceref.com/news/viewsr.html?pid=19668

-- ESA Venus Express Status Report: No. 13 - Spacecraft Thermal Characterisation

http://www.spaceref.com/news/viewsr.html?pid=19667

"Main Engine calibration burn has shown a working Main Engine thus giving the
green light for the last mandatory sub-system to be used for the Venus Orbit Insertion.

By coincidence the Main Engine calibration burn took place on mission day 100. During
the reporting period operations have been moved back to the Cebreros station and this
will be used as prime station from now onwards."

Posted by: ljk4-1 Feb 22 2006, 07:06 PM

Venus Express Ground Observing Project

The Venus Express Ground Observing Project (VEXGOP) is an opportunity to
contribute scientifically useful images and data to compliment the Venus Express
(VEX) spacecraft observations of Venus. The project will focus on utilising the
capabilities of advanced amateurs to obtain images of the atmosphere of Venus;
specifically filtered monochrome images obtained with CCD based cameras in the
350nm to 1000nm (near ultraviolet, visible and near infrared range).

The Venus Express (VEX) spacecraft will observe the planet Venus using seven
instruments for at least two Venusian years (1000 days) beginning in May 2006.
The instrument package includes the Venus Imaging Camera (VMC), which will image
the planet in the near-UV, visible and near-IR range. Although VMC will provide
much higher resolution images of the planet than visible from Earth, continuous
monitoring of the planet will not be possible.

There may be periods, therefore, when parts of the planet are visible from Earth
that are not visible from the spacecraft (due to the spacecraft position in
orbit). Additionally it is important to compare Earth-based observations with
simultaneous spacecraft observations. In particular this will allow us to extend
our understanding of the dynamics of Venus’s atmosphere based on the VEX data
to observations made prior to the VEX mission, as well as after completion of
VEX operations.

Objectives

The objectives of VEXGOP is to obtain high quality images of Venus before, after
and during VEX operations. Amateur astronomers, using CCD based cameras with
filters for specific band passes in the near ultra-violet, visible and near
infrared wavelengths (350nm to 1000nm), are encouraged to participate in the
gathering of images. Observation campaigns will include:

* Routine images of Venus during each apparition

* Coordinated observations during specific periods of the VEX mission to
provide either simultaneous or complimentary ground based images to VEX
spacecraft observations

For more details go to:

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38833

Posted by: Rakhir Mar 7 2006, 07:38 AM

Successful Trajectory Correction Manoeuvre

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38887

On 24 February a Trajectory Correction Manoeuvre was executed in order to trim the spacecraft trajectory after the Main Engine calibration manoeuvre. The manoeuvre executed flawlessly but the current knowledge of the orbit indicates that it is very likely that another fine tuning will be required once the orbital knowledge has increased.

Posted by: Rakhir Mar 13 2006, 12:51 PM

Preparation for Venus Approach

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38933

All calibration, science and maintenance activities of the instruments have been completed and focus is now on the Venus approach phase.

Posted by: Rakhir Mar 27 2006, 11:32 AM

VOI Events Timeline (11 April) :
- Spacecraft reorientation starting at 08:03 (CEST)
- 51 min engine burn starting at 09:19
- Reacquisition of radio contact after a 10 min occultation at 09:56

http://www.esa.int/esaCP/SEMJITM65LE_index_0.html

Posted by: Rakhir Mar 31 2006, 03:42 PM

New VOI timeline (slight modifications compared to previous release) :
- 09:17 --> VEX main engine burn starts
- 09:45 --> Occultation starts (loss of S-band signal)
- 09:55 --> Occultation ends
- 10:07 --> VEX main engine burn ends
- 10:10 --> Announcement by Flight Operations Director
- 11.07 --> X-band transmitter on
- 11:12 --> Telemetry received
- 11:30-12:15 --> Press Conference

All times above are 'Earth Received' time (CEST)

http://www.esa.int/SPECIALS/Venus_Express/SEMMM0NFGLE_0.html

Posted by: ljk4-1 Apr 3 2006, 02:08 PM

No.12-2006 – Paris, 31 March 2006

Venus within ESA probe reach

After its five-month, 400 million kilometre journey inside our solar system
following its lift-off on 9 November 2005, ESA’s probe Venus Express will
finally arrive on 11 April at its destination: planet Venus.

Venus Express mission controllers at the ESA Space Operations Centre (ESOC) in
Darmstadt, Germany are making intensive preparations for orbit insertion. This
comprises a series of telecommands, engine burns and manoeuvres designed to slow
the spacecraft down from a velocity of 29000 km per hour relative to Venus, just
before the first burn, to an entry velocity some 15% slower, allowing the probe
to be captured into orbit around the planet.

The spacecraft will have to ignite its main engine for 50 minutes in order to
achieve deceleration and place itself into a highly elliptical orbit around the
planet. Most of its 570 kg of onboard propellant will be used for this
manoeuvre. The spacecraft’s solar arrays will be positioned so as to reduce the
possibility of excessive mechanical load during engine ignition.

Over the subsequent days, a series of additional burns will be done to lower the
orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour
orbit around Venus early in May.

The Venus orbit injection operations can be followed live at ESA establishments,
with ESOC acting as focal point of interest (see attached programme). In all
establishments, ESA specialists will be on hand for interviews.

ESA TV will cover this event live from ESOC in Darmstadt. The live transmission
will be carried free-to-air. For broadcasters, complete details of the various
satellite feeds are listed at http://television.esa.int.

The event will be covered on the web at venus.esa.int. The website will feature
regular updates, including video coverage of the press conference and podcast
from the control room at ESA’s Operations Centre.

Media representatives wishing to follow the event at one of the ESA
establishments listed below are requested to fill in the attached registration
form and fax it back to the place of their choice.

For further information, please contact:

ESA Media Relations Division

Tel : +33(0)1.53.69.7155
Fax: +33(0)1.53.69.7690

Venus Express Orbit Insertion – Tuesday 11 April 2006

ESA/ESOC, Robert Bosch Strasse, 5 – Darmstadt (Germany)

PROGRAMME


07:30 Doors open

08:45 Start of local event, welcome addresses

09:10 ESA TV live from Mission Control Room (MCR) starts
09:17 Engine burn sequence starts
09:45 Occultation of spacecraft by Venus starts
09:55 Occultation ends
10:07 Main engine burn ends
10:20 Address by Jean-Jacques Dordain, ESA’s Director General, and other
officials

Break and buffet
Interview opportunities

11:30-12:15 Press Conference
Jean-Jacques Dordain, Director General, ESA
Prof. David Southwood, Director of Science, ESA
Gaele Winters, Director of Operations and Infrastructure, ESA
Manfred Warhaut, Flight Operations Director, ESA
Håkan Svedhem, Venus Express Project Scientist, ESA
Don McCoy, Venus Express Project Manager, ESA

13:15 End of event at ESOC

Venus Express Orbit Insertion – ESA/ESOC Darmstadt – 11 April 2006

First name: _________________________ Surname: __________________________
Media: ________________________________________________________________
Address: _______________________________________________________________
Tel: _______________________________ Fax: ________________________________
Mobile : ____________________________ E-mail: ______________________________

I will be attending the Venus Express Orbit Insertion event at the following
site:

( ) Germany
Location: ESA/ESOC
Address: Robert Bosch Strasse 5, Darmstadt, Germany
Opening hours: 07:30 – 13:00
Contact: Jocelyne Landeau-Constantin, Tel: +49.6151.902.696 – Fax:
+49.6151.902.961

( ) France
Location: ESA HQ
Address: 8/10, rue Mario Nikis – Paris 15, France
Opening hours: 08:00 – 13:00
Contact: Anne-Marie Remondin – Tel: +33(0)1.53.69.7155 – fax: +33(0)1.53.69.7690

( ) The Netherlands
Location: Newton Room, ESA/ESTEC
Address: Keplerlaan 1, Noordwijk, The Netherlands
Opening hours: 08:30 – 12:30
Contact: Michel van Baal, tel. + 31 71 565 3006, fax + 31 71 565 5728

( ) Italy
Location: ESA/ESRIN
Address: Via Galileo Galilei, Frascati (Rome), Italy
Opening hours: 07:00 – 14:00
Contact: Franca Morgia – Tel: +39.06.9418.0951 – Fax: +39.06.9418.0952

( ) Spain
Location: ESA/ESAC
Address: Urbanización Villafranca del Castillo, Villanueva de la Cañada,
Madrid, Spain
Opening hours: 8:30 - 13:30
Contact: Monica Oerke, Tel + 34 91 813 13 27/59 – Fax: + 34 91 813 12 19

Posted by: The Messenger Apr 3 2006, 05:28 PM

It looks like the ESA is making a very real effort to allow the public to witness the orbital insertion - complete with a mission scientist news conference. Does anyone know if NASA will patch the broadcast through on the NASA channel?

Posted by: RNeuhaus Apr 4 2006, 08:18 PM

QUOTE (ljk4-1 @ Apr 3 2006, 09:08 AM) *
Over the subsequent days, a series of additional burns will be done to lower the
orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour
orbit around Venus early in May.

That paragraph has paid me the attention. So fast in getting an orbit of 24 hours without any aerobraking in one month instead of 6 months of aerobraking that MRO must has to be performed in order to attain an orbit of less than 450 km around of the Mars' surface from the initial orbit of 420 km at pericenter and 48,000 km at apocenter.

It is understand that the MRO must have undergone further orbit adjustments that VEX does not perform but just will remain a highly elliptical orbit within 250 km of the planet's surface and withdraw to distances of up to 66,000 km.

The VEX's pericenter is no lower than 250 kilometers from Venus' surface, that means that at that height there won't be any aerobraking due to the atmosphere resistance. Then the Venusian atmosphere limit would be lower than 250 kilometers? For a comparisions, the Mars limit atmosphere is similar to Earth's ones but little higher by few tens kilometers and the Venusian atmosphere is almost twice higher than Earth?

Rodolfo

Posted by: RNeuhaus Apr 5 2006, 04:30 PM

Venus Express is going as cool toward the hot Venus:

The Venus approach phase is proceeding according to plan with all activities conducted successfully.

A Trajectory Correction Manoeuvre of about 13 cm s-1 has been executed in the evening of 29 March to reduce the pericenter altitude at Venus arrival by a bit more than 100 kilometres. The latest calibration of the nominal TCM gives the following results (uncertainties are 1-sigma):

* magnitude error = -1.2 mm/s (-0.9% +/- 2.1%)
* direction error = 0.8 deg +/- 0.3 deg

The final calibration will be made on 3 April. The current orbit determination does not show the need for any further trajectory correction.


http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39030

Rodolfo

Posted by: The Messenger Apr 5 2006, 04:56 PM

QUOTE (RNeuhaus @ Apr 4 2006, 02:18 PM) *
The VEX's pericenter is no lower than 250 kilometers from Venus' surface, that means that at that height there won't be any aerobraking due to the atmosphere resistance. Then the Venusian atmosphere limit would be lower than 250 kilometers? For a comparisions, the Mars limit atmosphere is similar to Earth's ones but little higher by few tens kilometers and the Venusian atmosphere is almost twice higher than Earth?

Rodolfo

Yes, it is much more dense, about 9x. There was a theory floating around a few years ago, that without the Earth's magnetic field, the solar wind would blow the atmosphere away. I don't know what became of this, but I don't see how Venus, with no magnetic field and much closer to the sun, could have an atmosphere at all, if the theory were true unsure.gif

Posted by: Rakhir Apr 7 2006, 11:47 AM

Two new articles for the preparation of the VOI.

ESA’s Venus Express to reach final destination
http://www.esa.int/esaCP/SEM0UGNFGLE_index_0.html
Some information on observations to be performed in capture orbit.


Final Preparations for Orbit Insertion
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39059
The fuel and oxidizer tanks have been pressurised and the helium tank is being warmed-up to properly sustain the main engine burn.
On 7 April, the essential commands for the VOI burn will be uplinked to the spacecraft.

Posted by: ljk4-1 Apr 10 2006, 04:38 PM

Drama in mission control

ESAPod goes to the heart of Venus Express and meets with a veteran ESA
operations engineer in the mission control centre. The large, well-equipped Main
Control Room enables flight controllers to work as a focussed team during
critical events and gives them the central facilities they need to communicate
with support teams worldwide.

Listen to this ESAPodcast at:

http://www.esa.int/SPECIALS/ESApod/SEMCVLNFGLE_0.html


ESA’s Venus Express to reach final destination

It was on 9 November last year that ESA's Venus Express spacecraft lifted off
from the desert of Kazakhstan onboard a Soyuz-Fregat rocket. Now, after having
travelled 400 million kilometres in only about five months, the spacecraft is
about to reach its final destination. The rendezvous is due to take place on 11
April.

Full story :

http://www.esa.int/esaCP/SEM0UGNFGLE_index_0.html

Posted by: ljk4-1 Apr 10 2006, 07:01 PM

Monday, 10-Apr-2006

On 11 April, Venus Express will arrive at Venus and enter orbit around the
planet. The spacecraft's main engine will perform a 50 minute burn, starting
around 07:10 UT, to slow the spacecraft and allow it to be captured by Venus's
gravity.

Updates on the Venus Orbit Insertion (VOI) activities will be posted on the page

http://sci.esa.int/jump.cfm?oid=39060

and on the ESA Portal Venus Express website

http://www.esa.int/SPECIALS/Venus_Express/index.html

ESA TV will broadcast live coverage of the event. For details see

http://television.esa.int


===================================================
KEEP IN TOUCH

+ SCITECH RSS
Subscribe to SciTech's RSS (Really Simple Syndication) feeds to get the latest
updates delivered directly to your desktop.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=37599

+ SCITECH SCREENSAVER
Don't forget to download the SciTech Screensaver a multi-facetted application
that allows you to keep abreast of status reports, news and announcements of
events taking place at ESA Science.
http://sci.esa.int/jump.cfm?oid=34651

Posted by: RNeuhaus Apr 10 2006, 07:27 PM

The start time of VOI : 7:07:59 UTC. That zone time corresponds to Greenwich line?

Rodolfo

Posted by: helvick Apr 10 2006, 07:39 PM

QUOTE (RNeuhaus @ Apr 10 2006, 07:27 PM) *
The start time of VOI : 7:07:59 UTC. That zone time corresponds to Greenwich line?

Yes but not BST which is 1 hour ahead at the moment.

Posted by: GravityWaves Apr 11 2006, 06:15 AM

QUOTE (Rakhir @ Mar 27 2006, 08:32 AM) *
VOI Events Timeline (11 April) :
- Spacecraft reorientation starting at 08:03 (CEST)
- 51 min engine burn starting at 09:19
- Reacquisition of radio contact after a 10 min occultation at 09:56

http://www.esa.int/esaCP/SEMJITM65LE_index_0.html


I think one of the best places to check for updates will be Emily's Blog

http://www.planetary.org/blog/article/00000527/

She's been at the ESOC

Posted by: Rakhir Apr 11 2006, 07:27 AM

QUOTE (GravityWaves @ Apr 11 2006, 08:15 AM) *
I think one of the best places to check for updates will be Emily's Blog
She's been at the ESOC


But she will not be able to post in real time.

There isn't wireless Internet access in the big room where the show is taking place, so I won't be able to post as frequently as I sometimes have on critical mission events. Instead, I'll take notes on what happens and when things get quiet I'll run back to the press room to post.

So I guess the most up to date information on the web should be the scrolling news bar on http://www.esa.int/SPECIALS/Venus_Express/index.html.

EDIT :
http://planetary.org/blog/

Actually Emily posted the information before the VEX home page.

Posted by: akuo Apr 11 2006, 07:47 AM

Good Luck VEX!

Don't know how much can be read into it, but at least the webcam at ESOC shows a green board on the screen:
http://www.esa.int/SPECIALS/Venus_Express/SEMN3Y274OD_0.html

Posted by: helvick Apr 11 2006, 08:05 AM

We seem to have re-acquisition of the s-band signal. No confirmation yet on success but events are following the plan.

Posted by: akuo Apr 11 2006, 08:11 AM

Emily: The main engine has shut down exactly on time!

Posted by: climber Apr 11 2006, 08:20 AM

Also from Emily's report :

Also, another useful tidbit this morning, is that Venus Express Project Scientist Håkan Svedhem reported on when the first images are expected: about 48 hours after VOI. They will be released to the public, the program moderator said, on April 13 after 4:00 p.m., I presume she meant Central Euroupean Summer Time, or 14:00 UTC

Posted by: Rakhir Apr 11 2006, 08:20 AM

http://planetary.org/blog/article/00000534/ smile.gif

Posted by: Sunspot Apr 11 2006, 08:56 AM

Weird , nothing at spaceflightnow.com They only seem interested in NASA missions now.

Posted by: remcook Apr 11 2006, 09:05 AM

I think they are waiting for the press comference and HGA data in a few minutes from now to see if the spacecraft is healthy.

Posted by: remcook Apr 11 2006, 09:27 AM

hurray! telemetry recieved!
http://www.planetary.org/blog/article/00000536/

edit: and..

http://www.esa.int/SPECIALS/Venus_Express/SEMZ7QNFGLE_0.html

Posted by: The Messenger Apr 11 2006, 09:36 AM

Is anyone getting the streaming video of the press conference> I;m getting zip.. mad.gif

Posted by: Sunspot Apr 11 2006, 09:42 AM

Im using BBC Online...The briefing doesnt seem to have started yet.

Now says its staring 10am GMT/11 BST

Posted by: Sunspot Apr 11 2006, 10:18 AM

My sound is cutting out.......have they actually said anything about its condition yet? lol


That was like some terrible oscar acceptance speech !!

Posted by: akuo Apr 11 2006, 10:59 AM

Emily has been busy. Almost the whole PC is already transcribed on the blog:
http://www.planetary.org/blog/article/00000537/

The PC ran only a few minutes late on the ESA stream, but otherwise the PR of this event was pretty bad. The quickest source of information was still Emily, even though she was runnin back and forth to the mission control and the press room! ESA should employ her for live event reporting :-P

Posted by: GravityWaves Apr 11 2006, 11:48 AM

QUOTE (akuo @ Apr 11 2006, 07:59 AM) *
Emily has been busy. Almost the whole PC is already transcribed on the blog:
http://planetary.org/blog/



I really enjoyed reading about Mars on this website but I must send out a big thanks to all you posters and members of UnmannedSpaceflight as well as the fantastic blog of Emily,
you guys have given this Venus event fantastic coverage

Posted by: remcook Apr 11 2006, 01:01 PM

spaceflightnow caught up...

http://www.spaceflightnow.com/venusexpress/060411voi.html

Posted by: Bjorn Jonsson Apr 11 2006, 01:17 PM

This is great news - congratulations to ESA (and thanks to Emily for detailed news from VOI and the PC).

Now we can look forward to seeing the first images two days from now. It's rather strange that with the exception of 50-100 Galileo images and a few from Cassini these will be the first spacecraft images from this closest neighbor obtained using a modern camera system.

Posted by: RNeuhaus Apr 11 2006, 01:47 PM

Damn smart is VEX! congratulations to the team! Also to Emily for the updated posting.

Rodolfo

Posted by: ljk4-1 Apr 11 2006, 01:56 PM

N° 13-2006 – Paris, 11 April 2006

Europe Scores New Planetary Success:
http://www.esa.int/SPECIALS/Venus_Express/SEM2GQNFGLE_0.html

Changed to a link - seriously, hundreds of lines ot text in a forum post doesnt make a lot of sense when you can just link to it with the pictures in situ etc. - Doug

Posted by: helvick Apr 11 2006, 02:38 PM

QUOTE (ljk4-1 @ Apr 11 2006, 01:56 PM) *
The PFS spectrometer will determine the temperature and composition profile of
the atmosphere at very high resolution.

So has the VEX PFS fixed itself then?

Posted by: odave Apr 11 2006, 02:43 PM

I don't think so - IIRC they were going to try the PFS cover again some time after VOI. That text just looks like a copy/paste job into the press release...

...and my congrats to ESA on the successes of VEX & MEX too! Now I think I'll go get some TEX-MEX for lunch wink.gif

Posted by: J.J. Apr 11 2006, 03:54 PM

Let me add my kudos to ESA and their fantastic job. Time to dust off the old Venus books! cool.gif

Posted by: hal_9000 Apr 11 2006, 06:46 PM

Podcast ESA.

http://esamultimedia.esa.int/multimedia/esc/venus_express_powers_into_orbit.mp4

Posted by: BruceMoomaw Apr 28 2006, 09:16 AM

There's a bit more from two abstracts from the Fall 2005 AGU meeting on just what they hope to do with VIRTIS where surface observations are concerned:

http://www.agu.org/cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm05&database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm05%2Ffm05&maxhits=200&="P33A-0227"

http://www.agu.org/cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm05&database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm05%2Ffm05&maxhits=200&="P33A-0225"

Also, Noam Izenberg's presentation to last November's VEXAG meeting on the observations MESSENGER will make during its second Venus flyby ( http://www.lpi.usra.edu/vexag/Nov2005/MESSENGER_VEXAG.pdf ) includes, on page 8, a description of a possible attempt to mkake similar observations of surface composition

Posted by: tedstryk Apr 28 2006, 08:41 PM

And don't forget VMC....



http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm05&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=sc%3dplanetary&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm05%2ffm05%7c1000%7c3633%7cVenus%20Monitoring%20Camera%20for%20Venus%20Express%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm05%2ffm05%7c22266835%2022270468%20%2fdata2%2fepubs%2fwais%2fdata%2ffm05%2ffm05.txt

Posted by: tedstryk Apr 28 2006, 09:29 PM

QUOTE (Richard Trigaux @ Jun 26 2005, 08:06 AM) *
This was all the more true for Huygens, which images were ridiculously small and tremendously compressed.



The images are not rediculously small...they are framelets....they were never intended to be stand alone images, but rather combined into panoramic 360 degree images. With early 90s technology, as edstrick said, this instrument did a very good job given the data rate/mass/power use constraints. It would have been better to have few images with less compression had both channels been received (with only one received, we would have horrible holes in the mosaics). But this is simply a result of Titan providing a lower contrast environment than expected.

Posted by: BruceMoomaw Apr 28 2006, 09:55 PM

That very nice (and pictorial) document on the DISR photos from last year's Titan Conference which I mentioned down in one of the Titan threads yesterday says that we did manage to get three "almost complete" mosaics, as opposed to the 10 hoped for.

Posted by: OWW May 9 2006, 05:58 PM

Venus Express has reached final orbit:

http://www.esa.int/esaCP/SEM33O8ATME_index_0.html

Posted by: RNeuhaus May 12 2006, 01:22 AM

Wait until June 4, 2006 when Venus Express start to collect observations from Venus. Now it is undergoing the switching on every 7 scientific instruments.

Until beginning of June, Venus Express will continue its ‘orbit commissioning phase’, started on 22 April this year. "The spacecraft instruments are now being switched on one by one for detailed checking, which we will continue until mid May. Then we will operate them all together or in groups" said Don McCoy, Venus Express Project Manager. "This allows simultaneous observations of phenomena to be tested, to be ready when Venus Express’ nominal science phase begins on 4 June 2006," he concluded.


Venus Express will live for only 2 days ! laugh.gif

While Venus Express is expected to spend about 15 months studying its cloud-covered target, the mission will span only two of the world’s exceedingly long days.

Rodolfo

Posted by: DonPMitchell Jun 8 2006, 12:44 AM

I hear the ESA has a scientific probe in orbit around Venus. Anyone else heard that? I wonder what it's doing? Do you think it might send back pictures? Maybe we will get to see them!

Posted by: lyford Jun 8 2006, 01:52 AM

Yes, I hear they plan daily releases of pics, a la MER. (Venusian days.)

Posted by: RNeuhaus Jun 8 2006, 02:16 AM

Maybe, the most-well informed is of Emily with her blog at http://www.planetary.org/explore/topics/venus_express/
However, the news is still cold dated May 9, 2006 as the most recent ones. I am afraid that the time will be cronometred as venusian day as Lyford is smelling! biggrin.gif

Rodolfo

Posted by: mchan Jun 8 2006, 03:21 AM

QUOTE (lyford @ Jun 7 2006, 06:52 PM) *
Yes, I hear they plan daily releases of pics, a la MER. (Venusian days.)

Sounds like the French pushed the choice of Debussy. smile.gif

Posted by: ustrax Jun 8 2006, 11:26 AM

'Until beginning of June, Venus Express will continue its ‘orbit commissioning phase’, started on 22 April this year. "The spacecraft instruments are now being switched on one by one for detailed checking, which we will continue until mid May. Then we will operate them all together or in groups" said Don McCoy, Venus Express Project Manager. "This allows simultaneous observations of phenomena to be tested, to be ready when Venus Express’ nominal science phase begins on 4 June 2006," he concluded.'

http://www.esa.int/esaCP/SEM33O8ATME_index_0.html

What did you want ESA to do before? Draws?...
Let's be patient and hope for some news on the following days...They'll appear...
I hope... huh.gif

Posted by: Toma B Jun 8 2006, 11:49 AM

QUOTE (ustrax @ Jun 8 2006, 01:26 PM) *
Let's be patient and hope for some news on the following days...They'll appear...
I hope... huh.gif

I was hoping for some images from SMART-1. Now there are somewhere around 20 total images...
ESA PR stinks... mad.gif sad.gif mad.gif

Posted by: ustrax Jun 8 2006, 11:55 AM

B)-->

QUOTE(Toma B @ Jun 8 2006, 12:49 PM) *

I was hoping for some images from SMART-1. Now there are somewhere around 20 total images...
ESA PR stinks... mad.gif sad.gif mad.gif
[/quote]

We're the MER-spoiled children... rolleyes.gif

Posted by: ljk4-1 Jun 8 2006, 12:54 PM

B)-->

QUOTE(Toma B @ Jun 8 2006, 07:49 AM) *

I was hoping for some images from SMART-1. Now there are somewhere around 20 total images...
ESA PR stinks... mad.gif sad.gif mad.gif
[/quote]

Instead of complaining to the choir, as it were, have you written to
ESA officials - especially those in charge of publicity - with your
issues, concerns, and ideas?

Posted by: Toma B Jun 8 2006, 01:04 PM

QUOTE (ljk4-1 @ Jun 8 2006, 02:54 PM) *
...have you written to ESA officials - especially those in charge of publicity - with your issues, concerns, and ideas?

Yes I have but I got no reply... sad.gif

Posted by: ustrax Jun 8 2006, 02:13 PM

There is a more recent update from the 6th of June:

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39343

And there are, since April, images available:

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=30913&fareaid=63

OK, it is not a flood of information but there is some...

EDITED: I've contacted the Project Manager Don McCoy but he will be out untill the 12th (maybe he will be at the world cup...who knows?... wink.gif )
Let's see if there is an answer by then...

Posted by: lyford Jun 8 2006, 03:04 PM

Yes, June marks the "Routine Science Operations" becoming, well, routine. (I, despite the highest respect I have for our Quebecois UMSF members, am grateful there are no http://www.montrealpoutine.com/ scheduled.)

I know I can rely on the grace and good humor of this board to get me through the longs dry spells between "daily" releases of information.

Though, as Ustrax pointed out, the VE website does appear to have weekly updates, which is a great thing if they can keep it going. And yes as far as images go like MRO they are few until the operational orbit begins which is now I understand. We should see more soon.

Posted by: ustrax Jun 8 2006, 04:04 PM

QUOTE (lyford @ Jun 8 2006, 04:04 PM) *
Though, as Ustrax pointed out, the VE website does appear to have weekly updates, which is a great thing if they can keep it going. And yes as far as images go like MRO they are few until the operational orbit begins which is now I understand. We should see more soon.


About the updates let's wait untill the 13th to confirm their periodicity... wink.gif

Don't expect to see much more before this:
'The next milestone for the mission is the preparation of the Mission Commissioning Results Review to be held end of June.'

Posted by: DonPMitchell Jun 8 2006, 06:09 PM

Looking at past missions, there is clearly a problem. People in the EU should apply some healthy critcism of this policy of closed data and image access. It is not appropriate to such an expensive publically-funded program.

Posted by: helvick Jun 9 2006, 12:02 AM

QUOTE (DonPMitchell @ Jun 8 2006, 07:09 PM) *
Looking at past missions, there is clearly a problem. People in the EU should apply some healthy critcism of this policy of closed data and image access. It is not appropriate to such an expensive publically-funded program.

as an EU citizen my only response to this is - I'm absolutely with you bud. Pressure is being applied little by little but we really need our own TPS here. Well a subset of the TPS that kicked some butt here would also be an option.

Posted by: AlexBlackwell Jun 9 2006, 12:17 AM

QUOTE (helvick @ Jun 9 2006, 12:02 AM) *
Pressure is being applied little by little but we really need our own TPS here.

Frankly, an "ESA Watch" (no doubt started by a former, disgruntled ESA employee who got laid off) or European versions of our own lovable Cydonuts would probably be more effective. You know, something along the lines of "C'mon, David [Southwood], why is ESA ignoring European taxpayers?" or "They're not showing the VEx data because they're hiding evidence of ancient civilizations on Venus!!!" tongue.gif

Posted by: BruceMoomaw Jun 9 2006, 01:08 AM

Well, yes, but where would the Europeans find someone that dotty? (By the way, a recent E-mail exchange with Keith -- of which I will spare you the sordid details, except that it started out with me trying to compliment him on something -- has confirmed again that his website should feature one of those warning labels that says, "Caution: Contains Nuts".)

Posted by: RNeuhaus Jun 9 2006, 04:00 AM

This seems that ESA is facing against the powerful democratic way which is the WEB where everybody is the witness of his taxpayer.

Rodolfo

Posted by: hendric Jun 9 2006, 04:46 AM

Pillinger, duh!

I mean, a Beagle-2 RINGTONE?!?

Posted by: Bob Shaw Jun 9 2006, 02:39 PM

QUOTE (lyford @ Jun 8 2006, 02:52 AM) *
Yes, I hear they plan daily releases of pics, a la MER. (Venusian days.)


Very funny! But perhaps all too true...


QUOTE (BruceMoomaw @ Jun 9 2006, 02:08 AM) *
Well, yes, but where would the Europeans find someone that dotty? (By the way, a recent E-mail exchange with Keith -- of which I will spare you the sordid details, except that it started out with me trying to compliment him on something -- has confirmed again that his website should feature one of those warning labels that says, "Caution: Contains Nuts".)


Bruce:

Well, I'm glad he doesn't lurk here, that's all I can say!

(C'mon Keith, 'fess up! We really do *love* ya, baby (in a stern, man-hug way, except for Ustrax, in whose case it's even more robust!)).

Bob Shaw

Posted by: ljk4-1 Jun 12 2006, 02:16 PM

Venus Express Commissioning Phase Completed

Paris, France (SPX) Jun 12, 2006

After 207 days of flight, 43 orbits around Venus and many test activities, Venus Express formally completed its commissioning phase June 3 and entered the routine science phase, ESA announced last week.

http://www.spacedaily.com/reports/Venus_Express_Commissioning_Phase_Completed.html

Posted by: ustrax Jun 12 2006, 03:15 PM

QUOTE (ustrax @ Jun 8 2006, 05:04 PM) *
About the updates let's wait untill the 13th to confirm their periodicity... wink.gif


They're right on schedule... smile.gif

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39386

Posted by: djellison Jun 12 2006, 04:48 PM

QUOTE (hendric @ Jun 9 2006, 05:46 AM) *
I mean, a Beagle-2 RINGTONE?!?


Guilty - I had that on my Nokia 3210 ohmy.gif

Doug

Posted by: ustrax Jun 13 2006, 09:18 AM

B)-->

QUOTE(Toma B @ Jun 8 2006, 02:04 PM) *

Yes I have but I got no reply... sad.gif
[/quote]

Here's an enlightning one from Monica Talevi (Science Information Manager), which Mr. Don McCoy believed to be the proper person to answer my question:

Let me try to answer your note. As you noted already, Venus Express started
its nominal science phase on 4th June, starting its observations on final
orbit.
As far as the presentation of scientific results is concerned, we are well
aware that our readers have to be a little patient....In fact, much
differently from NASA, ESA - by its constitution - doesn't fund the payload
(scientific instruments) of its spacecraft, which are on the contrary funded
by European Scientific institutes or National Space Agencies. The payload
scientists have priority right to use the scientific data for a few months
from their reception; only after this time ESA can claim back its full
property of the data.

Clearly, precise agreements are in place bewteen ESA and the payload
scientists as far as the use of PR images are concerned, but any delivery of
public outreach material must pass through a process that takes some time,
because the parties involved are several.

In any case, do not worry: soon you will see on the web new data and new
material: we are at work on it. So...stay tuned!

Posted by: The Messenger Jun 13 2006, 03:20 PM

This is encourgaging, but the time lag can be disheartening. It would be helpful to have access to all of the Huygens data by now...who knows - something in the data might have pushed a Titan/Enceladus mission ahead of Europa on the wish list...

Posted by: ljk4-1 Jun 13 2006, 03:22 PM

Ad astra per bureaucracia.

Posted by: DonPMitchell Jun 13 2006, 04:48 PM

QUOTE (ustrax @ Jun 13 2006, 02:18 AM) *
In fact, much
differently from NASA, ESA - by its constitution - doesn't fund the payload
(scientific instruments) of its spacecraft, which are on the contrary funded
by European Scientific institutes or National Space Agencies. The payload
scientists have priority right to use the scientific data for a few months
from their reception; only after this time ESA can claim back its full
property of the data.


But who funds those scientific institutes and agencies? The scientists didn't pay for Venus Express, European tax payers did, either through ESA or through other agencies. Also, the cost of the science payloads is often rather trivial compared to the cost of carrying them to Venus or Mars. It is very hard to argue that those images are not public property.

The University of Arizona built the camera on Huygens, and those pictures were released immediately. Nobody at U of A would say "these pictures belong to us!" I think criticism of this practice of witholding images and data should continue. In the long run, it will be good for ESA to change its attitudes, and it will get more public support.

Posted by: dilo Jun 13 2006, 06:01 PM

Cannot avoid to firmly agree with you, Don.
I think we european tax payers should be hungry about this stupid policy!

Posted by: helvick Jun 13 2006, 09:39 PM

QUOTE (dilo @ Jun 13 2006, 07:01 PM) *
Cannot avoid to firmly agree with you, Don.
I think we european tax payers should be hungry about this stupid policy!

I could not agree more. I can understand that ESA may well be limited in what they can do with regard to current missions where contracts may limit what they can and cannot do but the MER\Cassini examples have proven beyond doubt that there is a right way to do these things and it we need to make sure that in future the practice of releasing as much immediate data as possible becomes the minimum accepted practive.

Posted by: AlexBlackwell Jun 19 2006, 10:09 PM

There are two interesting articles in the http://www.blackwell-synergy.com/toc/aag/47/3: "http://www.blackwell-synergy.com/doi/abs/10.1111/j.1468-4004.2006.47313.x" by Andrew Coates and "http://www.blackwell-synergy.com/doi/abs/10.1111/j.1468-4004.2006.47316.x" by Peter M Grindrod and Trudi Hoogenboom.

Note for those who don't subscribe to A&G: The full Grindrod and Hoogenboom article can be downloaded http://www.homepages.ucl.ac.uk/~ucfbpmg/docs/paper_5.pdf.

Posted by: ustrax Jun 21 2006, 09:44 AM

'Report for Period 11 June to 17 June 2006

During the reporting period, Venus Express experienced its first Safe Mode since launch. This occured on 12 June, DoY 163, at the end of a data recovery action due to a ground station problem on DoY 162.'

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39400

Posted by: Rakhir Jun 27 2006, 07:21 AM

New press release today.

Double vortex at Venus South Pole unveiled

http://www.esa.int/esaCP/SEMYGQEFWOE_index_0.html

Posted by: DonPMitchell Jun 29 2006, 08:32 PM

QUOTE (Rakhir @ Jun 27 2006, 12:21 AM) *
New press release today.

Double vortex at Venus South Pole unveiled

http://www.esa.int/esaCP/SEMYGQEFWOE_index_0.html


Wonderful images. The north polar vortex was discovered and imaged by the Pioneer Venus orbiter. The VIRTIS team has a nice page about this, with discussion of prior work: http://www-atm.physics.ox.ac.uk/project/virtis/venus-polar.html

Posted by: hendric Jun 29 2006, 08:52 PM

In case there were any other morons like me who couldn't "get" the double vortex, you're only "seeing" the night-side half of the vortex in the pictures on ESA's webpage. The dayside half of the vortex is washed out!

EDIT: *sigh*, nevermind. I'm a moron (see above)

Posted by: The Messenger Jun 29 2006, 09:28 PM

QUOTE (hendric @ Jun 29 2006, 02:52 PM) *
In case there were any other morons like me who couldn't "get" the double vortex, you're only "seeing" the night-side half of the vortex in the pictures on ESA's webpage. The dayside half of the vortex is washed out!

EDIT: *sigh*, nevermind. I'm a moron (see above)

Me too rolleyes.gif

I would love to know how the density of the nightime vortex compares with the daytime - does each vortex unwind and expand during the day, and compress and wind up at night? Or visa versa?

Or is this just where the key is - the one inserted in the atmosphere to wind it up to superrotational velocities cool.gif

Posted by: elakdawalla Jun 29 2006, 09:43 PM

I sorted out the images at different wavelengths by date and put them on to a page here:
http://www.planetary.org/explore/topics/venus/venus_southpole.html

One strange thing: According to Hakan Svedhem there were six "slots" in which they could perform imaging, and most of the releases show six views of Venus' south pole. But in the "movie" that they released of the 5-micron image data, there is a 7th image (I think the second-to-last image in the sequence might be the extra one?).



When I annotated the animation with date/range information I made a guess as to what date/range it might be from. But after I tracked down this image from the presentation Svedhem made to VEXAG I don't think I guessed right.


Maybe that animation contains two views from "Slot #4", from the beginning and end of the observation period?

--Emily

Posted by: DonPMitchell Jul 1 2006, 10:38 AM

Thanks for gathering the images up on your blog. VIRTIS looks like it could reveal a lot more about the circulation of the atmosphere.

It looks like there has been progress in numerical modeling of the atmosphere too: http://www-atm.physics.ox.ac.uk/main/research/posters2005/2005cl.pdf

Posted by: ustrax Jul 3 2006, 02:13 PM

From http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39464:

'Activities of Medium Term Planning 003 will start now with great focus on the Earth occultations season that starts on 11 July and will continue till the end of August.'

Posted by: ustrax Jul 12 2006, 01:04 PM

Monica Talevi just e-mailed me...There are news from Venus, stay alert:

"Have a look to website this afternoon: we are about to post a new science
release on Venus Express!"

smile.gif

Posted by: elakdawalla Jul 12 2006, 04:25 PM

Here it is...lots of nifty new animations!

http://www.esa.int/esaSC/SEM9A3XAIPE_index_0.html

Thanks for the heads up, ustrax! smile.gif I'll be digging into these pictures thoroughly today...

--Emily

Posted by: AlexBlackwell Jul 12 2006, 04:35 PM

QUOTE (elakdawalla @ Jul 12 2006, 04:25 PM) *
Thanks for the heads up, ustrax! smile.gif I'll be digging into these pictures thoroughly today...

Nice PR eye candy by ESA but there is still a serious gap in science due to the ongoing PFS malfunction, notwithstanding the claim that "other instruments will cover some of the PFS objectives."

Posted by: ustrax Jul 12 2006, 04:41 PM

QUOTE (elakdawalla @ Jul 12 2006, 05:25 PM) *
Here it is...lots of nifty new animations!

http://www.esa.int/esaSC/SEM9A3XAIPE_index_0.html

Thanks for the heads up, ustrax! smile.gif I'll be digging into these pictures thoroughly today...

--Emily


Incredible ain't it Emily?... biggrin.gif
This mission will surprise us just more and more...

Posted by: elakdawalla Jul 12 2006, 04:52 PM

I realize now that these are the pictures that they said they'd release in association with their presentations to the 36th COSPAR, to take place in Beijing on 16-23 July. There's a http://www.cosis.net/members/meetings/sessions/accepted_contributions.php?p_id=170&s_id=2743. Wish I could be there but travel to China is a bit out of the question at the moment sad.gif

--Emily

Posted by: AlexBlackwell Jul 12 2006, 05:07 PM

QUOTE (elakdawalla @ Jul 12 2006, 04:52 PM) *
Wish I could be there but travel to China is a bit out of the question at the moment sad.gif

Have you ever been to China before? If not, I highly recommend the trip.

Posted by: The Messenger Jul 12 2006, 05:21 PM

Does anyone have a feel for the mean polarity of the Venus atmosphere is, with respect to the Earths? O2 and N2 are nonpolar, but I'm not sure about CO2, and H2O is highly polar - so are many sulfur compounds and all acids...

Polarity could come into play in interactions with the solar magnetosphere and the solar wind...magnitoshear?

Posted by: elakdawalla Jul 12 2006, 07:42 PM

QUOTE (AlexBlackwell @ Jul 12 2006, 10:07 AM) *
Have you ever been to China before? If not, I highly recommend the trip.
Nope...Lou Friedman has grabbed all the China trip opportunities to date. smile.gif Can't complain though as I have been sent to Cambridge, Noordwijk (in April! the tulips were fabulous), and Devon Island. Oh, and Darmstadt too, though Darmstadt in winter I do not recommend. --Emily

Posted by: DonPMitchell Jul 12 2006, 08:55 PM

Venus Express is the first time a decent camera has been placed in orbit around Venus, which is very exciting. Exploiting the narrow near-infrared windows, VIRTIS should show new details about the atmospheric circulation, cloud formation, and perhaps surface vulcanism.

I believe it was the Australian astronomer, David Allen, who first realized that these infrared windows existed into the deep Venusian atmosphere (Nature, 1984). Images were taken by the Galileo spacecraft during a flyby, and Mark Bullock has done some intersting work using Earth-based astronomy to peer through these windows: http://www.boulder.swri.edu/recent/VenusSwRI_PR.html

I am also disapointed by the PFS failure. This provides added incentive now for JAXA to send Planet-C and hopefully answer some of the questions about the chemical makeup of the Venusian clouds.

Posted by: elakdawalla Jul 12 2006, 11:41 PM

OK, so now I have a question about the images and movies.

Looking at the http://www.esa.int/esaSC/SEM9A3XAIPE_index_1.html, the caption states: "The spacecraft was flying over the northern hemisphere approaching the planet, over distances ranging between about 39 100 and 22 600 kilometres from the surface. The images were taken at 365 nanometres, starting respectively 03:30 and 01:45 hours before reaching the pericentre." But if you watch the movie it looks like we are actually moving from one hemisphere toward the equator on approach. The shape of Venus Express' orbit is such that you approach over the southern hemisphere, fly close over the equator and northern hemisphere, and then retreat back out over the southern hemisphere. And if you look at the orbit diagram (here's one I pulled from Håkan Svedhem's VEXAG presentation), the times and distances do imply that we're looking primarily at the southern hemisphere, moving toward the equator, I think. Am I seeing this right?

--Emily


Posted by: Bob Shaw Jul 12 2006, 11:44 PM

QUOTE (DonPMitchell @ Jul 12 2006, 09:55 PM) *
I believe it was the Australian astronomer, David Allen, who first realized that these infrared windows existed into the deep Venusian atmosphere (Nature, 1984). Images were taken by the Galileo spacecraft during a flyby, and Mark Bullock has done some intersting work using Earth-based astronomy to peer through these windows: http://www.boulder.swri.edu/recent/VenusSwRI_PR.html


Don:

My understanding of Mark Bullock's image is that it actually provides a negative view of the dark side of Venus - so here's an inverted version:

Bob Shaw

 

Posted by: DonPMitchell Jul 13 2006, 12:39 AM

Emily, I believe you are correct. The "flying over the northern hemisphere" phrase in their press release is confusing. I believe the movie we are seeing is "upside down" and we are coming up from the south. BY the way, the orginal gray version of the movie is much clearer than the blue-colored one.

Bob is right too. In the original Bullock image, the bright regions are thin spots in the clouds, where heat from the surface is shining through. That goes for the VIRTIS images too, I believe.

Posted by: DonPMitchell Jul 13 2006, 12:51 AM

I think ESA is following the standard NASA algorithm for how to ruin a beautiful space image:

step 1. Expand the contrast until light and dark areas pop.
step 2. Apply a Laplacian sharpening filter until noise artifacts are prominant.
step 3. Enlarge the image with a nearest-neighbor filter, so pixels are big and square.
step 4. Pick an ugly primary color, like orange or purple, and colorize the image.

Just to illustrate, here is the original Hubble image of Venus, and the one released to the press:


[attachment=6650:attachment] [attachment=6649:attachment]

Posted by: bdunford Jul 13 2006, 03:45 AM

A meaty new http://www.esa.int/esaCP/SEM9A3XAIPE_index_1.html is now online at the ESA site. It includes several animations and a wealth of science findings.

Posted by: Malmer Jul 13 2006, 04:10 PM

QUOTE (DonPMitchell @ Jul 13 2006, 02:51 AM) *
I think ESA is following the standard NASA algorithm for how to ruin a beautiful space image:

step 1. Expand the contrast until light and dark areas pop.
step 2. Apply a Laplacian sharpening filter until noise artifacts are prominant.
step 3. Enlarge the image with a nearest-neighbor filter, so pixels are big and square.
step 4. Pick an ugly primary color, like orange or purple, and colorize the image.

Just to illustrate, here is the original Hubble image of Venus, and the one released to the press:
[attachment=6650:attachment] [attachment=6649:attachment]


Its like they think that reality is too boring for the public. I think its ok to distort colors of objects that are commonplace and that people have a firm grip on. but anything that are uncommon exotic or in any way hard to reach for the common man should be depicted as close to reality as possible. otherwhise its deception.

I hate oversaturated contrast stretched space images. It only takes away the original beauty and subtleties of the real scene.

The first pictures from mars express are discustingly badly processed. the person that did it should be fired. The hubble picture is also quite garish.

why not just publish calibrated raw images?

/M

Posted by: DonPMitchell Jul 13 2006, 08:16 PM

In one of the early Venera-13 papers, the Russian authors discussed the need to apply the inverse method (solving an integral equation) to correctly create RGB color from sensor inputs. They knew their math and radiometry, but didn't have easy access to computers to do it. In the West, you have the opposite -- big computers and relatively ad hoc image processing. I don't believe the colors in any of NASA's images, even when they are not "false".

I'm not sure these guys even know about the sRGB standard. If you know the spectrum of a color, there is a clear algorithm for creating a 24-bit color value. That's fine for some of the latest cameras that record huge spectral image cubes. But if you have signal levels from several sensors, with various spectral responses, then the problem of deriving the maximum-likelihood color value is nontrivial.

Malmer, I was impressed by how you processed the Mariner-10 images, calibrating the sensor weights with Mariner's Earth images.

Posted by: Malmer Jul 14 2006, 06:48 PM

i actually ended up relatively close to the responsecurve that where in that paper you sent me...

Posted by: AlexBlackwell Jul 19 2006, 05:02 PM

QUOTE (elakdawalla @ Jul 12 2006, 01:41 PM) *
OK, so now I have a question about the images and movies.

There's an interesting tidbit about the Venus Monitoring Camera (VMC) in the News section of the July 20, 2006, issue of Nature:

'You can't have a mission without a camera'
Jenny Hogan
Nature 442, 234 (2006).
doi:10.1038/442234a; Published online 19 July 2006
http://www.nature.com/nature/journal/v442/n7100/full/442234a.html

A sister of the Mars Express probe has made it to Venus. And scientists have travelled to Beijing to discuss its first results. Horst Uwe Keller, who is presenting images from the craft's camera, spoke to Nature from the meeting.

I work on the Venus Monitoring Camera (VMC). One of our main objectives is to study the highest clouds, around 70 kilometres above the planet's surface.

The VMC is the only instrument newly developed for this mission, the rest were reused from Mars Express and the comet mission Rosetta. They didn't have a camera, so I stepped in and said: "You can't have a mission without a camera." We built something very small, 1–2 kg, to replace the tiny camera on Mars Express that had watched the Beagle 2 lander as it separated.

The VMC is four cameras, one for ultraviolet light, one for visible and two for infrared. The results so far are qualitative — we haven't finished calibrating the instrument yet. But in the sequences of ultraviolet images I presented on Monday you can see the clouds moving, showing the wind direction.

As a young postdoc in the 1970s, I remember being at a meeting where a well-known astronomer claimed that Venus's clouds were made of droplets of sulphuric acid. At the time I thought he was crazy, but now we know this is true.

What we don't know yet is the nature of the 'ultraviolet absorber' that creates dark features in our cloud images. We hope one of the spectrometers will work out what it is.

We are also working on the infrared images, which we'll check for hot spots that might be active volcanism. The surface of Venus is very young, so we know there must be some volcanism, but no one has definitively seen it. If we're lucky we could also find out something about Venus's lightning using the visible-light filter.

Some of the most remarkable results at the meeting have come from VIRTIS — a spectrometer that probes the atmosphere from top to bottom. The pictures of the south pole are really spectacular: they show a double vortex created by the movement of the atmosphere between the equator and the pole.

For our team, however, the challenge is simply getting high-quality images. While the spacecraft was cruising into orbit, our camera ended up pointing at the Sun for about 50 hours. The Sun burnt its image into the photodetector. But it's not a complete disaster: we have been able to compensate for the damage by re-measuring the sensitivity of each pixel.

Posted by: ugordan Jul 20 2006, 08:51 AM

QUOTE (AlexBlackwell @ Jul 19 2006, 06:02 PM) *
While the spacecraft was cruising into orbit, our camera ended up pointing at the Sun for about 50 hours. The Sun burnt its image into the photodetector. But it's not a complete disaster: we have been able to compensate for the damage by re-measuring the sensitivity of each pixel.

Ouch. sad.gif
I noticed the VMC images aren't fully flatfielded, but I didn't realize this was the reason.
How'd the thing get pointed at the sun for 50 hours? Safe mode? Isn't it supposed to be... well... SAFE?

Posted by: peter59 Jul 20 2006, 07:33 PM

QUOTE (ugordan @ Jul 20 2006, 08:51 AM) *
Ouch. sad.gif
I noticed the VMC images aren't fully flatfielded, but I didn't realize this was the reason.
How'd the thing get pointed at the sun for 50 hours? Safe mode? Isn't it supposed to be... well... SAFE?


Don't worry, images will be perfect. Images taken by ... Messenger.
Please forgive me my sarcasm, but waiting for ESA's images is like
"Waiting for Godot". wink.gif

Posted by: DonPMitchell Jul 21 2006, 03:05 AM

VMC is kind of a primitive camera (http://www.mps.mpg.de/projects/venus-express/vmc/), but that doesn't mean it won't spot something interesting. I think VIRTIS is a more sophisticated experiment, but probably won't take as large a volume of images as VMC. As for learning what the UV absorber is, I'm afraid that rested with the PFS. Its failure cost them the chance to learn a major new thing at Venus.

I think there is one other major new things that VEX could discover -- IR images of active volcanism on the surface. That would be incredibly exciting.

Posted by: edstrick Jul 21 2006, 11:07 AM

Assuming <I hope otherwise> that the PFS stays disabled, there could be a real opportunity to fly a backup/flight-spare/engineering-model of the instrument on the Japanese Venus atmosphere orbiter mission. It's moderately well along the design development cycle, but I suspect that it's not too late to refly the PFS on that mission.

Posted by: ugordan Jul 21 2006, 11:44 AM

What guarantee do we have that the backup wouldn't fail the same way this one failed? Wouldn't it be wise to reevaluate the weak points in the design and improve it if necessary. Meaning additional costs?

Posted by: cndwrld Mar 13 2007, 11:11 AM

Let me give a brief update about what I know regarding the publication of VEX science images and information, based on what I've heard over the last few days.

A major issue of Nature has been in planning for some time. It seems like it may come out in May, which would be nice since it would coincide with the one year anniversary of when VEX began routine science operations. Since most efforts now are focused on that paper, any other publications are unlikely until that issue comes out.

Getting more PR images out is getting pushed internally. I can't say that comments on this site have been taken into account, necessarily, but they are one factor that has been brought up in discussions. What I'm hearing now is that another PR person has been brought in at ESTEC to help Monica Televaes, and they are hoping to do the following:

- upcoming web stories in the end of March, 11 April and end of April.

- More information on the Ground based observations campaign will be coming up. There is a process in place to coordinate ground coverage of Venus during VEX observations, with the amatuer community.

-Try to do one web story per month, with one team each month.

-Try to put out more images in general.

It is possible they may fall short of this, but they are at least going to try it.

Cheers-

Don Merritt

Posted by: djellison Mar 13 2007, 11:42 AM

They are rapidly approaching the first scheduled PSA release of VEX data - but we've seen it all before with Smart 1 so I'm not holding my breath.

Doug

Posted by: ustrax Mar 13 2007, 12:21 PM

QUOTE (cndwrld @ Mar 13 2007, 11:11 AM) *
What I'm hearing now is that another PR person has been brought in at ESTEC to help Monica Televaes...


That's Monica Talevi...
Dear Dan Mirrit...you've got a http://www.unmannedspaceflight.com/index.php?s=&showtopic=3991&view=findpost&p=85314... wink.gif

Posted by: JRehling Mar 13 2007, 03:30 PM

Don, I could not appreciate your reports more. Thanks so much.

QUOTE (cndwrld @ Mar 13 2007, 04:11 AM) *
- More information on the Ground based observations campaign will be coming up. There is a process in place to coordinate ground coverage of Venus during VEX observations, with the amatuer community.


That's nice to read. Now that amateurs are combining interesting filters with other advanced techniques, some images of science quality seem to be appearing.

Cheers...

Posted by: dvandorn Mar 13 2007, 04:12 PM

And we'll likely see that amateur data before we ever see any VEX results... *sigh*...

Unless the VEX Science Operations Team is putting all this together to try and keep the *amateur* data secret, too??? blink.gif (OK, I'm not really serious about that. I don't think...)

-the other Doug

Posted by: lyford Mar 13 2007, 05:04 PM

QUOTE (dvandorn @ Mar 13 2007, 08:12 AM) *
And we'll likely see that amateur data before we ever see any VEX results... *sigh*...

Well, the mission isn't named VEX for nothing..... *ducks* rolleyes.gif

Posted by: Mongo Mar 13 2007, 10:51 PM

QUOTE (dvandorn @ Mar 13 2007, 04:12 PM) *
And we'll likely see that amateur data before we ever see any VEX results... *sigh*...

I am kinda hoping that amateurs end up 'scooping' the VEX people by publishing their results (if any) first. After all, the general rule is that he who publishes first gets most of the credit. The VEX people would have only themselves to blame, if their data (non)release policies end up costing them priority.

Bill

Posted by: helvick Mar 14 2007, 08:56 AM

The problem is that the amateurs almost certainly will only have acess to their own data so these coordinated ground based observations are unlikely to reveal much that is new without the corresponding VEX data.

However this is a really interesting effort and I'm very happy to see that ESA is also doing this - it seems to be similar to the collaboration with the amateur Jupiter observing community that NH benefited from during it's recent flyby.

And I'd like to thank Don for his updates - they very much appreciated.

Posted by: cndwrld Mar 14 2007, 12:33 PM

For those of you interested in the Venus data that amatuers are submitting to ESA,
the Venus Amateur Observing Project page is at:


http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38833&fbodylongid=1856

You can click on "Results and Observations" in the right sidebar if you'd like to see some of the results so far.

Cheers-

Don Merritt

Posted by: cndwrld Mar 26 2007, 07:38 AM

VEX Mission Ops Reporting, 11 - 17 March

At the end of the last CEB pass in the reporting period (DOY 076, 18:00z) Venus Express was
orbiting Venus at 195 million km from the Earth. The one-way signal travel time was 652 sec.

The Attitude and Orbit Control System (AOCS), power, thermal, mechanisms and fuel system continue to operate extremely well. Continued kudos to Astrium, and the flight control team at ESOC.

We did not receive a small amount of science data last week, because high winds at the Cebreros ground station required the antenna to be safed. That data was stored on board, and has now been downlinked. The data is transferred from Cebreros to a server at ESOC, in Darmstadt, Germany. Our science teams pull their data off of that, knowing that the data is not final for at least a week or two after the actual downlink, just for such occurences. This recent data delay will not cause any problems. The Cebreros station is new, the schedule being driven primarily by VEX support requirements; it still has that new ground station smell. There are occasional problems with equipment or procedures, but just the usual small stuff one would expect.

VIRTIS movie passes are scheduled for the second week of April (DOY 98-101). This includes five orbits, where the mission constraints allow us to take extended mosaic images of the south pole from apocenter. Planning of science operations during this event is now finished. A proficiency pass is scheduled on DOY 078
with DSS-63 (Madrid 70-m DSN antenna) to test system readiness for this activity. Being able to use the DSN 70-meter antenna means that it greatlly increases our data rate. Using the DSN station in Madrid, located in the 'same' spot as the Cebreros antenna, means that we do not need to make any changes in our usual orbit timing; we'll be downlinking at the same time as we would have if we had used the Cebreros station. We have made regular but limited use of the DSN stations; in the past, it was only for radio science observations. NASA has been very helpful in this regard; ESA isn't charged for the time, but on the other hand we get whatever time is left over. We put in requests; if no one else needs that antenna at that time, they give it to us. We are always in a position to get bumped, but it hasn't happened yet. So it is great that we get the time, as ESA doesn't yet have any 70-meter dishes.

The science planning for the 14th month of operations (MTP014) has been completed, and final checks are to be done shortly at ESOC in Darmstadt. The science planning for MTP015 has also been completed. Spacecraft pointing requests have been approved by Flight Dynamics, and the flight control team received the instrument commanding files last Thursday for their final checks. I sure hope they work. This set covers the second half of our quadrature period, and the special and special Messenger Fly-By support observations.

We've been so busy, time has flown by. But 11 April 2006 was the day we got to Venus, so our first anniversary of Venus operations is almost here.

Cheers-

Don

Posted by: cndwrld Apr 11 2007, 09:25 AM

Venus Express: One Year In Orbit

On 11 April 2006, VEX went into orbit around Venus. The ESA Science web page contains an article about it, which focuses on the oxygen airglow which is being investigated. The page is at:

http://www.esa.int/esaSC/SEM26GLJC0F_index_0.html

Posted by: ugordan Apr 11 2007, 09:33 AM

Nice, finally some new images and a cool movie!

Posted by: JRehling Apr 11 2007, 04:11 PM

It seems like this glow would be invisible to the eye. My mind leaps for an explanation for the ashen light, but it will probably end up being an optical illusion, not a real phenomenon.

Posted by: ngunn Apr 11 2007, 04:34 PM

QUOTE (JRehling @ Apr 11 2007, 05:11 PM) *
It seems like this glow would be invisible to the eye.


I'm not so sure. It's not clear from the press release whether this glow is monchromatic at 1.27 microns. It could just mean that it is being detected with that particular filter. Anyhow there could be more than one fluorescence-producing process, involving different molecules, operating either together or at different times and places in the atmosphere. The eye has the advantage over the camera when it comes to seeing over a very wide dynamic range of brightness, so I wouldn't discount the ashen light yet. What a wonderful atmosphere this is!

Posted by: cndwrld Apr 19 2007, 02:44 PM

VEX Mission Status

As of 14 April, Venus Express was orbiting Venus at 169 million km from the Earth. The one-way signal travel time was 564 sec.

From 08 April through 12 April, a series of special mosaic images of the south pole were taken with higher than normal resolution. The amount of data would exceed the capability of the nominal ESA ground station at Cebreros, Spain. The data was instead downlinked via the DSN 70-meter Madrid station, under a cross-support agreement between ESA and NASA. This South Pole 'movie' should show excellent coverage and detail of the south polar vortex.

was interesting to note that the brand-new Cebreros 35-meter antenna was 'shadowing' the DSN 70-meter, with no margin built in, and had as good a data rate capture as the much bigger DSN antenna. Which seems to indicate that the DSN 70-meter dish needs a little maintenance.

Some data was lost on DOY 101 due to bad weather in Spain. The data was recovered due to the shadowing with the Cebreros antenna. And all of us in Holland were glad to hear about bad weather in Spain.

Quadrature period begins in May. During this period, the spacecraft will switch to our smaller high-gain antenna, sharply reducing our data rate. The VEX bus is designed so that only two of the eight faces can be exposed indefinitely to the Sun. In the quadrature phase, we would get Sun exposure on the prohibited faces during Earth communications, which lasts at least eight hours per day. The spacecraft is then flipped, and Earth communications is done via the smaller high-gain antenna to keep the Sun exposure only on the allowed faces. The spacecraft is designed for this situation, but this is the first time in the mission we have been in this quadrature situation, so a lot of details on the ground have needed to be worked out and verified. The Flight Control Team at ESOC, in Darmstadt Germany, have been working on it for a while now, and final testing of the changes are underway now. The science planning for this period was wrapped up some time ago.

All spacecraft systems continue to operate nominally, with the occasionaly hiccup just to make sure that people are paying attention.

Posted by: babakm Apr 19 2007, 04:34 PM

Much appreciated update Don.

Posted by: cndwrld May 23 2007, 03:53 PM

New VEX Science Information Released

On the ESA Science page at: http://www.esa.int/SPECIALS/Venus_Express/
there are two new releases that you might find interesting.

The first shows some great 'movie' images taken by the VIRTIS imaging spectrometer of Venus' south pole. Combining the IR images with a UV image of the dayside, you can see the full rotation of the south polar vortex. Over a period of five orbits, VIRTIS took images centered around apocenter. The page strings them all together, so that you see the five or so shots from one orbit, and the sudden jump is when the data jumps to the images from the next orbit. You can really see the change in the cloud structure over time in the vortex.

Just released is an article about ground-based observations that will be taking place in coordination with VEX. This will extend up to the Messenger Fly-By in early June, when we will be (sort of) simultaneously taking data from Messenger, VEX and the ground.

Over the next few months, Venus will be around its closest distance to Earth (inferior conjunction). Planning began this week for late August through late September, slightly past conjunction, and during that period we'll also be coordinating VEX observations with some ground observations:
- Infrared observations will be made by the Infrared Telescope Facility (IRTF) facility in Hawaii, USA.
- Sub-millimetre observations will be made for two days with the James Clerk Maxwell Telescope (JCMT), located in Hawaii, USA.

Posted by: cndwrld May 25 2007, 01:32 PM

Venus Express Status

At the end of the last Cebreros pass in DOY 132, 18:00z, Venus Express
was orbiting Venus at 139 million km from the Earth. The one-way
signal travel time was 463 seconds. We are approaching inferior
conjunction, when Venus will be between Earth and the Sun.

The Venus Express spacecraft has been operating nominally, with only
relatively minor exceptions. One of these was a problem related to an
anomaly where a thruster failed to close. The thinking on that is
its "probably due to a missed pulse in the commanding
circuitry". I'd feel better if I knew what that meant, but even then
it would still mean that we don't know. We haven't seen a repeat, and
the best spacecraft problems are the ones that fix themselves.

With the installation of a flight software patch and the update of the
on-board ephemeris, Venus Express was configured for the quadrature
phase. This phase is defined as the period during which the
Sun-Spacecraft-Earth angle is between 75° and 95°.

During the quadrature phase, revised operating constraints on the
VMC camera lead to the necessity for changing the spacecraft attitude to
prevent unacceptable illumination of the VMC camera. To this end, fake
ephemerides on the positions of the spacecraft and the Earth were
uploaded to Venus Express.

On 11 May 2007, for the first time, Earth pointing was achieved
using fake ephemerides with a Sun illumination of ~10 degrees on
the +Y spacecraft face. The first pass with a tilted attitude was
closely monitored by the Flight Control Team (FCT). No anomalies
related to quadrature operations were detected and the performances
of the system was nominal. The flight control team and flight
dynamics teams at ESOC, in Darmstadt Germany, spent a large amount
of time and effort in planning this 'quadrature' exclusion period,
but it all looks good now. We're in Quadrature, in the
exclusion period, and it is all working perfectly. The ESOC flight
control and flight dynamics teams are very good.

Later in the quadrature phase, a swap to the smaller High Gain Antenna 2
is required for Earth communications, as the spacecraft attitude for
continued use of HGA 1 would result in illumination of spacecraft
faces not designed to cope with such exposure. This is scheduled for
01 June, and will immediately drop our downlink data rate from 228 Kbps
to 28 Kbps. Its unfortunate that during inferiour conjunction, our data
rate has to drop so much. Re-using the Mars Express design allowed
the VEX mission to get funded, but one consequence is that the thermal
constraints force things like this.

It looks like we've had our first non-recoverable failure. It appears that
the S-Band downlink path has a problem which significantly reduces our
downlink power on S-Band. That's the bad news. The current indications
suggest that the problem lies in the path between the entry to the RF
switch immediately prior to the HGA 1 antenna, and the antenna itself.
The good news is that radio science, which used to rely on having both
the X-band and S-band downlink, can now use only the X-band downlink
along with models of the Earth ionosphere (which replaces the need for
the S-band signal). There is still a lot of work being done, to try and
figure out exactly what happened, and more importantly, why.

Some delays have been encountered in the data deliveries for ingestion
to the archive, but a first release of (a subset of) Venus Express
data in the Planetary Science Archive (PSA) is still expected for
this summer.

The preparations for a special section on Venus Express results
(some 9 papers), to be published in Nature, are ongoing.

Planning for our sixteenth monthly medium-term plan of operations (MTP016)
are completed. We are just now finishing MTP017, and MTP018 planning started
this week.

Posted by: AlexBlackwell May 25 2007, 07:48 PM

http://www.esa.int/esaCP/SEMLYY8RR1F_index_0.html
European Space Agency
23 May 2007

Posted by: The Messenger May 25 2007, 11:13 PM

QUOTE (cndwrld @ May 25 2007, 07:32 AM) *
It looks like we've had our first non-recoverable failure. It appears that the S-Band downlink path has a problem which significantly reduces our downlink power on S-Band. That's the bad news.

???
Wasn't one of the instruments non-functional from the get-go? PFS? Fourier IR or something?

Posted by: cndwrld May 29 2007, 07:11 AM

You're right. The PFS instrument
(http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33964&fbodylongid=1444)
never worked. The mechanical scanner is stuck.

I guess I don't count that because technically, they are still trying to free it. The flight control team is working with PFS to do a test shortly where they try to move it while we are doing a burn. Which is trying to kick it and turn it at the same time.

We don't hold out much hope. But one never knows.

Posted by: cndwrld Jun 21 2007, 01:37 PM

There was some discussion about getting data down from spacecraft, and frustration with the amount of time it takes. I think I finally figured out how to post images, so I'll put up a couple examples from VEX to show how this stuff gets downloaded.

When we do our planning, our ESA proprietary simulation tool will create a prediction of how much data the instruments accumulate each orbit, as well as how much we are able to downlink during each comm pass with the Cebreros Station in Spain.

The resulting up-and-down graph looks like this, for our 18th monthly plan which I just finished:



This is a bad, bad MTP, because the data does not go to zero at the end of it. We have some restrictions on our downlink towards the end, and one can see that at the end of the 28 day simulation period, we have accumulated data which has not been downlinked. This causes problems with the planning, not on the spacecraft.

This image is the same simulation output, but for MTP015. The Messenger fly-by was in orbit 411, as I recall. We had a few passes where we could not downlink data, while we were accumulating data in support of the fly-by. Once the Messenger pass was over, we started our downlinks, but it took a while to get the data down.


Some instruments, who don't take large data volumes, had their data down within a couple passes. The instrument with the highest data volume, the VIRTIS imaging spectrometer, took days to get it all down.

I don't know how the Messenger data came down. But I'd assume that they got a certain amount of time on one antenna each day, so the data would get downlinked in pieces over a period of days. Their downlink would look different, but probably similar: A big increase in on-board data, followed by one or more dumps of a few hours each to get the data down.

Posted by: brellis Jun 21 2007, 02:38 PM

hi cndwrld

thanks for providing a window into the dataflow workings

"There was some discussion about getting data down from spacecraft, and frustration with the amount of time it takes. I think I finally figured out how to post images, so I'll put up a couple examples from VEX to show how this stuff gets downloaded.

When we do our planning, our ESA proprietary simulation tool will create a prediction of how much data the instruments accumulate each orbit, as well as how much we are able to downlink during each comm pass with the Cebreros Station in Spain."

Is the storage capacity on V.E. heavily-burdened?

As to transmission back to earth, I wonder if there could be a software on the spacecraft similar to the program that updates a web page, looking for numbers that change. For example, once a normal temperature range in a given area over a given time period has been established, the craft prioritizes data that appears outside the norm for sending back to earth.

Similarly, I've wondered how "smart" the Mars orbiters can get as they "pushbroom" their way around the planet. Perhaps they can automatically notice small changes like new gullies.

Posted by: cndwrld Jun 22 2007, 07:20 AM

>>Is the storage capacity on V.E. heavily-burdened?
Well, yes and no. The instruments (particularly the imaging spectrometer VIRTIS and the VMC camera) could take much more data than they do. We are usually limited by our data rate, and our ground contact periods, not the SSMM volume.

>>I wonder if there could be a software on the spacecraft similar to the program that updates a web page, looking for numbers that change.

I'd see two problems with this. First, it only would work with housekeeping telemetry, not with science data. And the housekeeping is much less in volume than the science data. We dump a fixed 216 Mbits per orbit for housekeeping data; we dump about 4200 Mbits per orbit of science data. It might be a useful idea in some circumstances, though. Say, on spacecraft on long duration missions in cruise phase, where all you have housekeeping telemetry and no science, or commercial spacecraft.

Two, you'd only get data when it changed. But in that case, if you are looking at telemetry to find a problem, you would have to trust the numbers you don't have. You'd have to believe that if no data came down, that everything was working and the number you got last week is still the number you have now. I would have real trouble doing that. In my experience, data that doesn't exist has an unknown value, and the item generating the data doesn't work unless it proves it works by putting out data. Things 'fail silent' all the time.
Again, though, in certain circumstances, it might be useful.

Posted by: cndwrld Jun 22 2007, 08:49 AM

VEX Status, 22 June 2007

At the end of the last Cebreros ground station pass on DOY 167, 18:00z,
Venus Express was orbiting Venus at 97 million km from the Earth. The
one-way signal travel time was 323 sec. We are executing our 15th monthly
plan, MTP015, and beginning the first week of MTP016 next week. We are still
operating on the small high-gain antenna, HGA2, due to Sun angle on the
spacecraft during Earth Pointing.

We are currently in the Quadrature Period, meaning that the angle
Sun-Venus-Earth is less than 90 degrees. Only two faces of the spacecraft
can take long-term solar exposure, +X and +Z. During parts of this
Quadrature Phase, these two faces can only face the Sun if we point with
the smaller antenna. So our data rate, when we are closest to Earth, is
pretty low. Kind of counter-intuitive, one could say.

During short periods of Quadrature, near the beginning and end, when in
normal Earth pointing the +Z face of the spacecraft (the one with all the
instrument fields-of-view) was too close to the Sun. We want to prevent light
falling in the VMC camera field-of-view, as they don't have a shutter and found
out after launch that direct sunlight on their camera CCD causes degradation
to the plastic lenses. So for the past few weeks, we were operating with a
10 degree roll whenever we were in Earth pointing, to keep the Sun out of
the VMC field-of-view. For a spacecraft with tight pointing requirements and
precise pointing systems, it was not easy to find a way to make it continually
position itself 10 degrees off what it knew to be correct. But the team in ESOC
in Darmstadt figured out how to do it. Last week, we finished our need for this
offpointing, so we are back to normal pointing modes now. Still on the darn
small antenna, though.

No new problems have developed lately. Flight control systems and power are
fine; still have plenty of gas. Some instrument glitches occur now and then,
but nothing too worrisome. VIRTIS did a big upload to their instrument to
update their operating system and take care of some small errors they were
getting. The PFS instrument, stuck since launch, is going to be operated
during some momentum wheel off-loadings, when the thrusters are fired, in
the hope that moving it and kicking it at the same time might jar it loose.
The other earlier problems have not gone away: S-band downlink is way too
weak due to expected thermal damage on large antenna or cabling; thruster
abnormal firing which occurred but has not re-appeared; SPICAV shutter
gives odd readings now and then. But nothing new lately.

The radio science experiment team was able to do a Bi-Static Radar test last
week. This is where we turn on a special, ultra-stable transmitter, point the
big antenna at a feature on the surface, and blast away at full power at such
an angle that the reflected signal goes towards Earth, where it is usually
captured at Europe's antenna at New Norcia, Australia. The geometry between
Venus Express, a surface feature of interest and the ground station have to
be just right in order to do it, so we've only done five or six of these so
far in the mission. With low staffing, data analysis has not been what you
would call timely. Upcoming BSR observations have been cancelled because
they have discovered that the latest BSR data are significantly different
from what was expected and won't give them the information they need. It
will take a bit of time for them to figure out what to do next.

All the data from the Messenger fly-by support is on the ground, and being
looked at. We hope to see some press releases soon. The ground-based
observing campaign will be ending soon, as Venus moves further away from
Earth. We had a bit of a panic last week with the Moon's occultation of
Venus. One of our team realized that our downlink files didn't take the
occultation into account, and there was much rushing about. Turns out that
the occulation occurred in The Netherlands and Germany, but the Cebreros
station in Madrid was just outside of the occulation area. Which is why the
files didn't take it into account.

Planning began this week for two monthly plans in parallel, meaning double
the work for us and the instrument teams for the next four weeks. But we
are doing this because most of the teams take a month off for the summer
holidays. We'll work harder for a month so they can take a month off. I
think most of our team will not take a lot of time off during the summer.
Since none of us have kids, we can take our holidays outside of the rush
period in the summer.

In this planning period, we are introducing a new type of pointing that our
software will now support, called 'track pointing'. We should be able to
give a start time, and end time, and the lat/lon/elevation of a point, and
the spacecraft will track the point. Or we can give it
the name of a astronomical object in our database, and it will track the
object. I say that we should be able to do these things. The software has
a few 'issues' that were discovered recently, so we are going to just
allow a couple of them in each of the MTPs we are starting to plan now.
We'll see how it goes. If it works, though, it will probably get heavily
used.

In summary, things have not gotten calm and boring yet, we're doing a lot
of science that people can whine about not seeing but which should be more
published soon, and the spacecraft is doing well. Our next Science Working
Team meeting is near Rome in July, and I'm going to stay over an extra
day to finally go see the Pantheon, and the remains of the Venus temple
in the Forum. I'll pay my respects to Venus while I'm there.

Posted by: dvandorn Jun 22 2007, 03:56 PM

QUOTE (cndwrld @ Jun 22 2007, 02:20 AM) *
>>Is the storage capacity on V.E. heavily-burdened?
Well, yes and no. The instruments (particularly the imaging spectrometer VIRTIS and the VMC camera) could take much more data than they do. We are usually limited by our data rate, and our ground contact periods, not the SSMM volume.

So, here's a question -- is the download rate limited more by intrinsic limits on data transfer rates (i.e., the spacecraft's transmitter power and the size of its dish), or by the relatively short periods of time you have the Cerberus facility available to receive downlink? (I know you have some attitude issues which result from VEX being designed to orbit Mars and not Venus, but I'm looking for average data transfer rates, here, not those that are constrained by other parameters.)

What I'm getting at, here, is whether or not a vastly expanded Deep Space Network would aid appreciably in getting more data off of the vehicle, thereby letting you take as much data as the instruments can actually collect.

I hate to see a valuable resource being under-utilized because of bottlenecks in our ability to get data back from it. And I'm wondering if it just isn't time for an expanded DSN to be started. If it could be funded by an international consortium that gets its seed money from something other than charging rapacious hourly rates, that would be even better... but I keep hearing more and more issues with the ability to get data back from our spacecraft that are out there exploring the unknown, and it just seems bass-ackwards to spend billions of dollars on a well-designed probe and then hamstring its science return because we have an antiquated DSN that can't keep up with demand and yet still charges thousands of dollars (or Euros, or what-have-you) an hour for the privilege of using it.

Maybe we ought to have everyone convert their unused Dish Network dishes into a vast distributed amateur Deep Space Network and offer its services to all comers, first-come-first-serve...? biggrin.gif

-the other Doug

Posted by: Gsnorgathon Jun 23 2007, 11:47 PM

QUOTE (cndwrld @ Jun 22 2007, 08:49 AM) *
...
we're doing a lot of science that people can whine about not seeing
...

Well, I should hope so. Imagine the whining if you weren't doing a lot of science!

Posted by: cndwrld Jun 25 2007, 07:33 AM

QUOTE (dvandorn @ Jun 22 2007, 05:56 PM) *
So, here's a question -- is the download rate limited more by intrinsic limits on data transfer rates (i.e., the spacecraft's transmitter power and the size of its dish), or by the relatively short periods of time you have the Cebreros facility available to receive downlink? (I know you have some attitude issues which result from VEX being designed to orbit Mars and not Venus, but I'm looking for average data transfer rates, here, not those that are constrained by other parameters.)

What I'm getting at, here, is whether or not a vastly expanded Deep Space Network would aid appreciably in getting more data off of the vehicle, thereby letting you take as much data as the instruments can actually collect.


Well, let me mumble a bit while I try to think of something to say. Hmmph, hmm.

The limits on the downlink data volume are basically data rate and time of contact.

How to increase time of contact for an orbiting planetary spacecraft? We could have a steerable antenna, so that the only time we didn't have the ability to point at Earth was when we were occulted. We could transmit data and point the instrument platform to take new data at the same time.

We'd have more contact time, and more flexibility, if we could get as much time on the Earth networks as we wanted. VEX is limited to using the Cebreros station. But if Europe had its full network up (i.e. the third antenna, in addition to New Norcia, Australia and Cebreros, Spain), and each station had multiple antennas large enough for planetary probe reception (> 30 meter, say), and we could jump from station to station as the stations rotated out of view, then we could continue our downlinks as long as we wanted. It is worth keeping in mind that most stations are quite heavily booked these days. So it isn't just about upgrading networks, but expanding support would mean building additional dishes.

To increase the data rate, the spacecraft (steerable) antenna should be larger (while also pointing very accurately). And the ground station antennas should be larger, while also pointing very accurately. We use Cebreros, which is 35 m. DSN can give us 70 meters, which we used once and it let us pump a lot more data through. Transmitter power isn't really a problem for VEX, because power is not a problem. On some probes, it might be an issue. But its a design issue; it is easily scaled up for most missions, probably with minimal weight increases. The data rate also changes with distance from Earth, but there's not much we can do about that. I'm gonna assume for the foreseeable future that antennas will be fixed in size.

The problem with all of this, of course, is cost. No surprise there. A 35 meter antenna, with sufficient accuracy and senstivity, is incredibly expensive. A 70 meter is, well, more. Mulitple sets of antennas in the same location multiplies the price. Bigger antennas on spacecraft are expensive, but more (I am guessing) for launch cost than construction cost. You've got to get it in the launch fairing. The extra weight is expensive. And if you are too heavy and get pushed from one class of vehicle to another (say, Delta to Titan, or whatever), the difference in cost can be enormous. The ability to steer larger antennas accurately gets more expensive: motors, sensors, etc. Also more expensive in operations, although it can be largely autonomous now, I think (i.e., if you're on star trackers, you should be able to just say, 'point to Earth'.)

Can we simulate a bigger antenna on a spacecraft if we use two or three small antennas, separated from each other? Someone will have to tell me the highs and lows of that idea. But one promising thing is somehow getting a bigger antenna for smaller launch cost. Some commercial telecom spacecraft (like the Thuraya cell phone system) and military death stars use collapsible (or expandable) antennas, but I don't know much about them and I'm not a comm guy. Since they don't seem to have taken off, I'm assuming there are reasons for that. Cost again, probably.

I would spend all the money that people are willing to pony up, of course. I'm an engineer, and more expensive toys are always more fun. I happen to feel that we are already spending an awful lot of money, and we are getting the science down. So if we hit some constraints along the way, it doesn't bother me too much. When I worked on Magellan mapping Venus (or in my case, looking at radar telemetry while smart people mapped Venus), it was great fun. I hear that Magellan mapped about 73% of the surface. If we had spent an extra $20 million and gotten 80%, would it have changed very much? I guess the answer to that is up to the individual, but I'm pretty happy with 73%. With VEX, we should outlive our design life, and meet all our science goals, for an amount of money that Europe was willing to pay. And they are paying for Rosetta, and Bepi-Columbo, and ExoMars, one of which I hope to have an opportunity to work on. I guess I'd rather have mulitple missions with reasonable contraints than one or two more perfect missions. I'm biased, of course; I need a job.

I hope that answered some of your questions, Doug.

Posted by: dvandorn Jun 25 2007, 01:35 PM

Yes, that answers a lot of my questions -- thanks! I guess one thing I was wondering was whether a dozen, or a hundred, little (like half- to one-meter) dishes on the ground could be used in a sort of an "antenna farm" mode to simulate a 70m or larger receiving antenna.

You see, there are literally hundreds of thousands of people here in the U.S. who have at one time or another used a satellite cable system (like Dish Network) but who no longer use that service. That's a lot of parabolic dish receiving antennas that are just going to waste.

If all of those unused dishes were mounted with decent views of the ecliptic (where most of the unmanned probes spend their lives) and tracking mounts, and set to communicate to a central data collection center, we could have a "distributed" DSN network made up of thousands of dishes. And heck -- some of them could be tracking Venus, some Mars, some Mercury, and some Saturn. And some tracking points in between.

I know it's probably a foolish pipe dream, but it would seem that you could vastly expand the DSN (within North America, at least) at relatively little overall cost (certainly at relatively little cost per dish) by making use of these unused dishes.

Your response tells me that such a network of dishes could be useful for getting additional science out of the assets we have in place around the Solar System. That's the information I was looking for. Now all we have to do is find the seed money for outfitting these unused little dishes, and we can get started... smile.gif

-the other Doug

Posted by: djellison Jun 25 2007, 01:53 PM

An upgrade for the DSN based on arrays of modest ( <30m but >1m ) sized dishes is under serious study - with a test dish being used at JPL - (I think it's 12m).

Doug

Posted by: JRehling Jun 25 2007, 04:42 PM

QUOTE (cndwrld @ Jun 25 2007, 12:33 AM) *
When I worked on Magellan mapping Venus (or in my case, looking at radar telemetry while smart people mapped Venus), it was great fun. I hear that Magellan mapped about 73% of the surface.


From the Magellan page on Wikipedia: <<By the end of its first such eight-month orbital cycle between September 1990 and May 1991, Magellan had sent to Earth detailed images of 84 percent of Venus' surface. The spacecraft then conducted radar mapping on two more eight-month cycles from May 1991 to September 1992. This allowed it to capture detailed maps of 98 percent of the planet's surface.>>

I think your recollection of the low-ish figure around 73% may be based on one of the three distinct imaging campaigns covering (only) that much of the planet. Magellan had unexpected operational issues that cost some of the expected coverage. Eventually those issues were worked out and the orbiter could have been kept running to finish the job had funding been available. As it happens, there was decent "fill" data for the 2% Magellan didn't cover, so no one's lost much sleep over it. The next radar mission to Venus will be about higher resolution coverage of what Magellan did map.

Posted by: cndwrld Jun 29 2007, 01:03 PM

VEX Mission Status

Quadrature is the period when the Earth-Venus-Sun angle is less than 90 degrees, which includes inferior conjunction. At the start and end of quadrature, we have to undertake special operations in order to avoid Sun exposure into the VMC instrument which has no shutter. On 16 June, the spacecraft's 10° +Y tilt was removed at the end of the first quadrature transition period.

Removal of the 10° +Y tilt was removed by execution of previously
uploaded commands, just prior to start of the Earth communications pass.
It was done this way so that the spacecraft orientation could be checked
immediately upon the start of communications with Earth, and time for the
science downlink would not be used to observe the orientation change.


Routine observations took place during this reporting period, and
occurred as planned. A full VIRTIS software upload was carried out
including the related testing on DOY 165 and 166.

On DOY 167, the telemetry bitrate changed to 45 kbps.

At the end of DOY 167, Venus Express was orbiting Venus at 97 million km
from the Earth. The one-way signal travel time was 323 seconds.

Payload Activities have been routine. Two VeRA radio science occultation
observations were performed using the ESA New Norcia antenna in Australia
on DOY 164, 166, 168, 170 and 173. For these observations, a highly stable
local oscillator is used to generate the downlink signal to Earth, a ground
antenna locks on the signal, and the signal is measured as the spacecraft
is occulted behind the planet. This is repeated when the spacecraft leaves
occultation and emerges from behind the planet. The spacecraft is re-oriented
during the occulation to account for the diffraction of the atmosphere, to
maintain the link withe the ground station. The changes in the signal are
used to determine properties of a deep slice of the atmosphere. Since this
was in the quadrature period, the smaller high gain antenna was used, greatly
limiting the signal strength.

A VeRA Bistatic Radar observation was also performed, using the 70m Canberra
DSN station on DOY 163. In these experiments, the stable oscillator is used
for the downlink to the big high gain antenna, and the antenna is pointed at
a ground feature and tracks it. The reflected signal is detected by the Earth-
based antenna, which is why the large 70 meter DSN antennas must be used.

For the VIRTIS imaging spectrometer, a full instrument operating software
upload and related testing were carried out on DOY 165 and 166.

On DOY 170, a new on-board control procedure (OBCP) was uploaded for
SPICAV shutter operation. The OBCP is expected to automate the operations of
the SPICAV shutter. The shutter is closed when the instrument is not in use,
because exposure to direct sunlight would damage the instrument optics.
The commands have been inserted into the normal command uploads to the
spacecraft for shutter operations, but in the case of a spacecraft safe
mode the shutters would not have gotten closed and might have exposed the
instrument to hours of exposure in the worst case.

PFS spectrometer tests are being prepared to try to move the instrument's scanner during
a wheel off-loading (WOL). The instrument is non-functional due to a stuck
scanner. It is hoped that operating the scanner motor while the thrusters
kick the spacecraft might free the scanner. Hoped, but not expected.

Today I plotted out the fuel, oxidizer and helium pressurant since the start of the mission.
The state of the consumables is just fine, and VEX life will be limited by money much more than
by fuel. The plot below shows how much was used to get into orbit; since then, we've been using
very little. We've got room for some big orbit changes if it is decided to try something new.


Posted by: lyford Jun 29 2007, 05:17 PM

Thanks for the update! I always enjoy reading them even if I don't always comment.

When will we know about the PFS?

Posted by: cndwrld Jul 2 2007, 07:43 AM

PFS has delivered their inputs for the Scanner test during a wheel off-loading. The tests are to be run over 6 days, during the last three weeks of July.

They'll want to look pretty closely at the data for any signs of movement, and no one is in a hurry to announce bad news. So I wouldn't expect us to get any official word on the result until about mid-August. But that's just my guess.

Of course, if the thing actually moves, we'll hear about it in no time. This test is a Hail Mary pass, so I'm not holding my breath. Still, would be nice if it worked.

Posted by: The Messenger Jul 4 2007, 05:23 AM

...so no news is bad news...



The ESA gets kudos for a brave, daring, and resourceful use of a 'hammer'

Posted by: cndwrld Jul 4 2007, 07:01 AM

We have a bigger hammer in reserve. This test is during a wheel offloading, where we hold the spacecraft steady with thrusters while dumping the momentum from the reaction wheels. The thruster burns are quite small.

If this hammer doesn't work, they might do the same thing but during an orbit correction maneuver. An OCM is usually a bigger burn, proportional to the amount of delta-V(elocity) that flight dynamics decides we need to get back into our correct orbit.

It still seems unlikely to help. But what the heck. The PFS team is operating their instrument on Mars Express, but it isn't like their too busy to do this test. And the flight control team is probably starting to get bored. Can't hurt to try it.

So we'll kick it. And in the noble and honorable tradition of engineering, if it doesn't do what we want then we'll kick it harder. While calling it a naughty name.

Posted by: cndwrld Jul 23 2007, 02:37 PM

PFS Still Non-Operational

The PFS scanner was commanded during recent momentum dumps (wheel off-loadings). Reaction wheels speed up in order to capture unwanted spacecraft momentum and maintain pointing; when the wheels are slowed back down to their zero level (generally once a day), thrusters are fired to hold the spacecraft steady. It was hoped that the physical shock of the thruster firings, performed at the same time the scanner was commanded to move, might jog the scanner lose.

However, kicking the scanner in this way didn't work. No more tests are planned, that I'm aware of. The orbit correction maneuvers, which I thought might be tried, turn out to be smaller than the wheel off-loadings. So trying them is not thought likely to help.

So, we'll have to see if the PFS team can come up with another Hail Mary pass, or if this is the end.

Posted by: lyford Jul 23 2007, 04:27 PM

Thanks for the update, though I wish the news was better. I guess the problem with moving parts is that they sometimes aren't moving parts.....

QUOTE (cndwrld @ Jul 23 2007, 07:37 AM) *
So, we'll have to see if the PFS team can come up with another Hail Mary pass, or if this is the end.
Are ESA missions allowed to use American football sports idioms? But if they come up with a long shot that works, I would gladly allow them to use whatever idioms they deem necessary.... smile.gif

Posted by: cndwrld Jul 24 2007, 07:22 AM

I work on an ESA project, but I'm an American. I'm afraid I don't know any European sports idioms.

Posted by: lyford Jul 24 2007, 03:00 PM

I was trying to think of what the football (soccer) equivalent of a "Hail Mary" would be myself but couldn't. I think this reflects the poor state of my sports knowledge and of European slang.biggrin.gif

Thanks again for all your inside reporting, cndwrld.

Posted by: Stu Jul 24 2007, 03:20 PM

I'm afraid I don't know any European sports idioms.


Try Sven Goran Erikson. Oh, sorry, idioms... I thought you said something else...

tongue.gif

Posted by: nprev Jul 25 2007, 01:49 AM

Based on a casual Google, perhaps ESA might consider launching the aforementioned individual on a purely ballistic intercept trajectory with VEX in order to jar PFS loose...didn't see a whole lotta love there, Stu!

Posted by: cndwrld Jul 27 2007, 09:56 AM

Coordinated observations of Venus between VEX and Messenger

The ESA web page for the Messenger fly-by is now up, on the ESA Space Science page, at
http://www.esa.int/esaSC/index.html

If you click on the third story, labeled, "Venusian rendezvous results: chapter one", you go to the dedicated fly-by page at:
http://www.esa.int/esaSC/SEMVN4HYX3F_index_0.html

The fly-by page can also be reached from the dedicated Venus Express page at:
http://www.esa.int/SPECIALS/Venus_Express/index.html

Posted by: Rakhir Sep 3 2007, 07:06 PM

500 days at Venus, and the surprises keep coming
http://www.esa.int/esaCP/SEMNOCMPQ5F_index_0.html

...Some of the first detailed analyses are now being completed and will soon be published in acclaimed scientific journals...

Posted by: ustrax Sep 7 2007, 11:41 AM

QUOTE (Rakhir @ Sep 3 2007, 08:06 PM) *
500 days at Venus, and the surprises keep coming
http://www.esa.int/esaCP/SEMNOCMPQ5F_index_0.html



About this anniversary I'm starting today a special issue at http://spaceurope.blogspot.com/, today's guest is http://spaceurope.blogspot.com/2007/09/venus-express-mission-reached-important.html, VIRTIS Co-PI, no shocking announcements but the fact of having people from the team sharing some thoughts is quite revolutionary...and appreciated... wink.gif

Posted by: cndwrld Sep 18 2007, 01:57 PM

Venus Express Status

At the end of the last Cebreros pass in the reporting period (DOY 251, 15:00z) Venus Express was orbiting Venus at 52.0 million km from the Earth. The one-way signal travel time was 172 seconds.

Overall, the spacecraft is performing well, and most of the instruments are working great. During MTP 018, which is finishing this week, we completed 500 orbits and have sent to Earth around 1 Terabit of data so far.

Of the four science operations engineers, two are now moved to the European Space and Astronomy Centre near Madrid, Spain. Another will join them in October. And I expect to move down from The Netherlands sometime in January. Within the next half year, all of ESA's planetary science operations, as well as their astronomy science operations, will be based at ESAC, Spain.

on 23/08/07, DOY 235, we performed an S-Band test. As you may recall, our S-Band downlink on the main antenna HGA-1 is very much reduced in output. Tests had earlier shown that the problem was definitely in the HGA-1; these tests confirmed that it was in the antenna itself, but there's no telemetry on the antenna. It is possible that some physical deformation took place, but anything is just speculation. 14. VMOC has scheduled a mapping and calibration of the S-Band downlink, which will occur in MTP021. The calibration put out a carrier over the S-band HGA-1 output, and slew the spacecraft back and forth past the Earth. Since the downlink is so reduced, we will need a 70 meter antenna to pick up the carrier very well, so we will do the test using the Canberra DSN to capture the downlink signal strength. We can then look for distortions in the signal pattern.

The S-band calibration slot is currently scheduled for Orbit 584, DOY 330, on 26-Nov-07 between 00:30 and 04:00Z.
It will take place over the Canberra DSN antenna, towards the end of the visibility period and coming up directly before the Cebreros AOS. It will occupy the pericenter arc, with some margin due to its relatively long duration (3hr 30min).

The calibration is HOT (sun exposure on sensitive faces), and so there can be no hot observations prior to it in orbit 584 and we must be thermally recovered from any previous observations. The recovery time from the calibration is covered within the following Cebreros pass, which will allow hot observations to resume as normal in Orbit 585. The VMC camera was approved for observations during the antenna calibration, as the +Z axis will be pointing at the planet.

We need the S-band for bi-static radar observations. That's where they point the big antenna at the surface of Venus, blast out the carrier signal (but in a very stable oscillator mode) and catch the reflections on Earth using a DSN antenna. Without the S-Band, they can't correct out for the Earth's atmospheric distortion. They thought they could use models to do it, but I guess it didn't work out as well as hoped. In the mean time, we aren't doing any BSR observations. Since we seldom get the right geometry to do them, we are not missing many. But then again, there aren't many to miss.

On August 23rd, the spacecraft came into view at the Cebreros station bearing bad news. There had been some type of problem wtih a solar array drive motor, during the observations, and the system had switched to the B side units. The spacecraft controllers and engineers cleaned it up and reset everything. Now they needed to figure out why it happened, since the A side stuff seemed to be just fine.

They didn't have long to wait to get more data. The next day, on 24/08/07, DOY 236, VEX came back into Earth view with the same problem, only worse. The solar array drive electronics (SADE) showed a motor with a failed status and a mispointing between the two solar panels. The control team manually switched off all the payload and as much power-sucking stuff as possible, and cleaned it back up again. Given that it happened twice in two days, the spacecraft left Earth pointing and with payload off until it was figured out.

This is believed to be related to a known MEX anomaly, which uses the same motors and electronics. The anomaly testing was completed, after a couple days of the spacecraft being left Earth pointing with the payload off. The solar panel pointing has been successfully corrected. I haven't seen a full report on the problem yet, but it hasn't come back.

In other Payload Activities, the ASPERA nuetral and charged particle detector, MAG magnetometer, SPICAV stellar/solar spectrometer and VMC camera seem to be working well.

And the VIRTIS imaging spectrometer? Well, not so much. Virtis is in two wholly separate parts: the M and H instruments. The M instrument has a large field of view (FOV), the H a very small one. They both need to be cooled prior to use of the IR detectors, and use motors to move the cooling fluid around. It was noted by the Flight Control team that one of the motor telemetry channels went out of limits. And that is when they noticed that the cooler motor currents had been fluctuating wildly for some time, just not out of limits. A test that included the VIRTIS H cooler was performed on DOY 251. Otherwise only Virtis M part has been operated during this period as the failure on H cooler is still under investigation. And since the cooler motors are the same, M is operated in a somewhat limited mode. So far, it seems that the M motor is not effected. Testing on the H motor continues, to try and characterize it. The Virtis instrument team is really good, so we trust them to do a good characterization, and we'll see if we can do anything or not. We can run the motor the way it is, of course. But once it fails, no coolant motor means no coolant, which means no crycooler cooling, which means Virtis-H IR detector data.

To summarize, things go well but not perfectly. Keeps it interesting.

Posted by: cndwrld Oct 16 2007, 02:48 PM

Nature Papers

On 29 November 2007, a special issue of Nature magazine will highlight the first major papers from each of the instruments on the Venus Express mission. A press conference is planned for 28 November to highlight the release.

Should be a great issue.

Posted by: elakdawalla Oct 16 2007, 05:01 PM

Hooray hooray hooray! According to what Hakan Svedhem told me, waiting for this publication has been a logjam that prevented more science from coming out (not necessarily by press releases, I mean as presentations by scientists at meetings). It will be a great relief to see some Venus Express results in publication.

cndwrld, does your posting of this date mean that all of the teams have gotten their papers submitted?

--Emily

Posted by: cndwrld Oct 17 2007, 06:50 AM

Yes, my understanding is that everything is in, accepted and ready to go. Given the history of this issue, I wouldn't say that nothing can go wrong now. But we hope that it is finally going to happen. Three months into the Extended Mission, it would be nice to see something published....

Posted by: cndwrld Oct 30 2007, 11:59 AM

Venus Express Status on 30 October 2007

For those interested, here's an update on Venus Express. The Flight
Control Team publishes regular updates on the web at:
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=41488

The Main bus activity last week, on mission day 710, 19/10/2007, DOY 292
was the switch to quadrature offset (tilted) operations by the loading of
fake ephemereids. The process was fully automated following the
experience of the quadrature entry. For a two week period when
the Sun-Venus-Earth angle is 90 degrees, the Sun can fall directly
into the VMC field of view, which has no shutter, when we are Earth
poinging. The spacecraft needs to be rolled 10 degrees and maintained
there when in Earth pointing, which was not a planned state when the
spacecraft was developed. To do this, fake information (ephemerides)
are loaded; the spacecraft uses the same positioning system, but the
references are shifted by 10 degrees. The fake ephemeris was applied
after the science observations, and just before the acquisition of signal
(AOS) at the Cebreros ground station near Madrid. This 10 degree roll
also means that the Sun is kept for very long exposures on surfaces
that we normally keep cool. This means that for two weeks, our Earth
pointings (which should be cool and allow us to cool down) are hot
(so that cooling takes place during the normal science observation
periods). It is all quite messy, but doing it the second time was
much easier. We are in the transition to exit the quadrature period,
and only have to do this for a couple weeks.

We also switched from the small high gain antenna (HGA-2) to the bigger
one (HGA-1). The smaller one has to be used during quadrature because
of the Sun exposure angles on the spacecraft, to keep the Sun off of
the cooling arrays. Now we're back on the big dish, so our data rate
goes up. That's always a good thing. The TM bit rate starting on Orbit
549 (22-Oct-2007, DOY 295) was 38 Kpbs. After the antenna swap,
the bit rate went to 228 Kbps. But as Venus will be moving away
from Earth now, our data rate soon begins dropping a lot. The low point
comes in about May 2008, when we hit Superior Conjunction.

At the end of the Cebreros pass on Orbit 548 (21-Oct-2007, DOY 294),
at 18:00z, Venus Express was orbiting Venus at 94.6 million km from
the Earth. The one-way signal travel time was 315 sec.

The operations of the VIRTIS imaging spectrometer were disabled for the
past month. Really unusual currents in the cooling motors was detected
last month by the Flight Control Team in Darmstadt, Germany. To be safe,
the instrument was shut down except for unusually interesting
observations. The Virtis team in Frascati (Rome) has worked with the
motor manufacturer, and new procedures to use the motors were developed.
After which, the manufacturer changed their minds and decided that the
old procedures were better and safer. Operations are expected to
resume next week or the week after.

The rest of the instrument observations have been taking place routinely,
with the occasionaly glitch here and there.

Current NTO (Oxidizer) Mass (Kg): 46.761
Current MMH (Fuel) Mass (Kg): 29.514

During the NASA Phoenix mission's final approach to Mars, ESA will
support NASA by performing Delta-DOR measurements in order to get the
best positioning data possible. Venus Express was used as a test of the
Delta DOR procedures at the end of September and early October,
performing three Delta-DOR tests. The results show that we are still
at Venus.

The special issue of Nature magazine on Venus Express results is
expected to be published on 29 November, and should be accompanied by
a press conference the day before. The last paper was accepted
yesterday, so it should be all finalized. However, it has taken so
long to get these papers submitted that I'll believe it when I get
a hard copy in my hands.

The VEX teams are starting to get pretty good images of the surface
of Venus, through the frequency 'windows'. Hopefully a few web images
will come out before too long.

There are four science operations engineers working on Venus Express.
As of last week, three of the four have been re-located to work at
The European Space Astronomy Centre (ESAC) near Madrid. The fourth
engineer (me) will be moving at the end of January. All the ESA planetary
science operations will soon be based there. As a consequence, the
facility's name is expected to change, to The European Planetary and
Space Astronomy Centre (EPSAC).

Posted by: nprev Oct 30 2007, 06:22 PM

Thanks for the update, CND. Sounds like good things are coming in about a month...looking forward to the surface imagery! smile.gif Will be interesting to compare it to Magellan radar data.

Posted by: helvick Oct 31 2007, 08:39 AM

QUOTE
The results show that we are still
at Venus.


That must be a relief. smile.gif

Excellent update again don. Thanks.

Posted by: The Messenger Oct 31 2007, 05:49 PM

There are a few things still orbiting Mars that we do not hear from either;)

Posted by: ustrax Oct 31 2007, 08:53 PM

QUOTE (The Messenger @ Oct 31 2007, 05:49 PM) *
There are a few things still orbiting Mars that we do not hear from either;)


You are probably slightly http://www.dlr.de/mars/en/desktopdefault.aspx... wink.gif

Posted by: rlorenz Nov 1 2007, 03:17 AM

QUOTE (cndwrld @ Oct 30 2007, 07:59 AM) *
Venus Express Status on 30 October 2007
......
There are four science operations engineers working on Venus Express.
As of last week, three of the four have been re-located to work at
The European Space Astronomy Centre (ESAC) near Madrid. The fourth
engineer (me) will be moving at the end of January. All the ESA planetary
science operations will soon be based there.


Are you gonna miss Noordwijk ?
I was a YGT at ESTEC 1990-1991 on Huygens, still fond memories of
the beach, Koop Avond, Annies Verjahrdag etc..... At least Madrid
should be sunny...

Posted by: rlorenz Nov 1 2007, 03:21 AM

QUOTE (rlorenz @ Oct 31 2007, 11:17 PM) *
Are you gonna miss Noordwijk ?


Duh sorry - you're at ESOC, right? Of course you won't miss Darmstadt,
very few redeeming features, except maybe the Ratskeller.

Posted by: cndwrld Nov 1 2007, 08:35 AM

I'm at ESTEC now, in Holland. And I am definitely going to miss this place, both ESTEC and Holland. The Netherlands is a wonderful place, Leiden a beautiful, fun town.
I can't afford to live in Madrid, so it will be nearby. If Spain and the new town aren't wonderful, too, 'll be very upset.

Posted by: cndwrld Nov 7 2007, 08:43 AM

Stellar Occultation Studies at three planets

The Principal Investigator for on of the Venus Express instruments has written a short brief about the use of stellar occulation measurements being performed by European spacecraft now at three planets: Venus, Earth and Mars. You can read the release at:

http://www.esa.int/SPECIALS/Venus_Express/SEMEH3FWB8F_0.html

Posted by: cndwrld Nov 7 2007, 03:50 PM

Eleven VEX Papers On-Line

On the ESA Science and Technology page for Venus Express, eleven papers have been put on line. They cover the seven science instruments, the spacecraft, the ground segment and mission planning, science data handling and science planning.

They can be accessed by going to the VEX Science web page at

http://sci.esa.int/science-e/www/area/index.cfm?fareaid=64

and then clicking on 'Publications' under the 'Services' header at the lower left.

Posted by: ustrax Nov 9 2007, 01:48 PM

VMC surface images http://www.esa.int/esaSC/SEM57353R8F_index_0.html.

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