Rakhir
Apr 13 2006, 03:22 PM
JRehling
Apr 13 2006, 04:24 PM
Good stuff. Kudos to the team for successful operations and a quick first release.
I'm curious as to the wavelengths in the dayside image. It's probably stretched beyond "human" RGB to show that much detail, but it would be fantastic to have a multispectral dataset and sate some curiosity about what a "true" color spacecraft image of Venus would look like. VEx will answer this question as well as one could expect.
The IR nightside makes me wonder about the prospects of seeing the surface through the cloud layers. That's a whole lot of cloud signal. Maybe greater temporal coverage will show us the surface in peeks here and there. Also, other IR may show the surface signal better.
I'm surprised how the UV image looks -- quite different from the Pioneer images. Lots of calibration questions.
Rakhir
Apr 13 2006, 04:55 PM
QUOTE (JRehling @ Apr 13 2006, 06:24 PM)
Good stuff. Kudos to the team for successful operations and a quick first release.
We just have to hope that the next releases will be as quick as the first one.
However, given the PR history and what was available for the VOI, it is probably only a dream
ollopa
Apr 13 2006, 05:37 PM
Anyone here smart enough to work out the lat/lon gridlines for these first images? Presumably a half decent astronomy programme would at least tell where the subsolar point was on Venus @ say 9:07 UT on the 11th..
JRehling
Apr 13 2006, 06:33 PM
Well, since the axial inclination is only 3 degrees, you can count on the apparent pole always being pretty close to the actual pole. There's only one real degree of freedom in the subsolar point.
dilo
Apr 13 2006, 08:27 PM
UV map seems to show surface details, but this should be only my impression (atmosphere should be more transparent in IR and visible features do not match with radar maps around south pole...).
Click to view attachmentThis is a small, naif combination of visible + UV image (former was veirated toward red while latter was detail/contrast enhanced).
Julius
Apr 13 2006, 09:23 PM
The deepsest features visible are estimated at 55 km above the Venusian surface.Thats according to ESA website.
JRehling
Apr 14 2006, 01:11 AM
UV shouldn't ever show surface detail, I don't think. The clouds reflect UV and absorb it, but shouldn't let very much pass through. There is an unknown UV absorber that "marks" some clouds and leaves others unaffected.
IR will not show the surface at many wavelengths of IR. The temperature of Venus produces an IR glow in many wavelengths, and CO2 absorbs it at others. It is not so neat a situation as at Titan.
BruceMoomaw
Apr 14 2006, 01:48 AM
Nope, UV NEVER punches through to the surface -- but some limited near-IR spectral bands do, and Galileo's near-IR maps of Venus in those wavelengths during its flyby provided a temperature map that matched up beautifully with radar maps of Venus' surface topography. Venus Express' far more detailed and sensitive surface temperature maps should be able to reveal any small regions of current surface volcanism. The real question is whether they will be able to pierce the cloud interference enough to also provide at least a little data on surface composition near the north pole (or at least a distinction between granitic and basaltic rocks).
deglr6328
Apr 14 2006, 05:08 AM
Even if the atmosphere were cloud-free I suspect that the extreme rayleigh scattering of UV light and the immense thickness of the atmosphere alone would preclude the possibility of imaging any detail. Here's an image of the CN tower which has been ruined by UV dispersion.
elakdawalla
Apr 14 2006, 10:41 PM
I got some more info out of Kevin Baines about these images...
http://www.planetary.org/news/2006/0414_Fi...mages_Peel.html--Emily
RNeuhaus
Apr 15 2006, 01:01 AM
QUOTE (elakdawalla @ Apr 14 2006, 05:41 PM)
I got some more info out of Kevin Baines about these images...
http://www.planetary.org/news/2006/0414_Fi...mages_Peel.htmlVery good explaining. From that URL, I was able to understand better about the different layers of colours around the Venus' South pole. Neither VIRTS (Visible and Infrared Thermal Imaging Spectrometer) and VMC (Venus Monitoring Camera) are able to map the Venus Surface. So Venus Express will not take the same pictures as did the extint Magellan probe, won't it?
Rodolfo
BruceMoomaw
Apr 15 2006, 02:25 AM
Not at all -- no radar on this one. However, VIRTIS WILL be able to provide a good deal of entirely new and important surface information -- which, combined with its atmospheric science, is why it's the single most important instrument on the craft.
Unfortunately, the currently-stuck PFS is the second most important; and it's important for the two instruments to make their atmospheric observations simultaneously. For this reason, I imagine they will put in considerable effort -- and even be willing to run some risks -- to unstick it.
RNeuhaus
Apr 15 2006, 01:29 PM
I was not aware of Planet Fourier Spectometer (PFS) that is stuck now. What was the problem?
An extract from ESA's portal on Venus Express
PFS will be able to measure the temperature of the atmosphere between altitudes of 55–100 kilometres at a very high resolution. It will also be able to measure the surface temperature and therefore be able to search for volcanic activity. In addition to its temperature measurements, PFS will be able to make composition measurements of the atmosphere.Will the PFS be able to deduct the surface contour according to its temperature? I don't believe it as a reliable indicator since the surface might have different refraction/absorption properties of light/heat.
QUOTE
VIRTIS WILL be able to provide a good deal of entirely new and important surface information
What kind of surface information will VIRTS provide?
Rodolfo
Rakhir
Apr 15 2006, 01:34 PM
QUOTE (RNeuhaus @ Apr 15 2006, 03:29 PM)
I was not aware of Planet Fourier Spectometer (PFS) that is stuck now. What was the problem?
Rodolfo
Rodolfo,
check
this thread for the stuck PFS.
-- Rakhir
Decepticon
Apr 15 2006, 04:39 PM
Did anyone catch the Venus Express TV Special on Science channel?
I was surprised how fast it went to air.
At the end of the ep you see the images released so far.
It interesting to see the discussion of life and whats it's really like on the surface.
4th rock from the sun
Apr 16 2006, 12:32 AM
QUOTE (elakdawalla @ Apr 14 2006, 11:41 PM)
I got some more info out of Kevin Baines about these images...
http://www.planetary.org/news/2006/0414_Fi...mages_Peel.html--Emily
And that info helps a lot :-) ! Here are some processed images based on the released image.
Atempt to process the IR and UV data into a visible image, using CIE colourspace convertion.
Click to view attachmentIR data (950 and 1700) full polar image. Some data was cloned to fill the missing parts, so this is more of a "creative" image than scientific.
Click to view attachmentSame as above in cylindrical projection.
Click to view attachmentAn atempt to derive "visible" maps from the IR data.
Click to view attachmentClick to view attachmentThis first images show a lot of details and I can't wait for more images to come!!!
Sunspot
Oct 11 2006, 10:01 PM
http://news.bbc.co.uk/1/hi/sci/tech/6041570.stmScientists at the Division of Planetary Sciences meeting in Pasadena, California, this week said that data streaming from the Venus Express probe had provided unprecedented detail of the Venusian atmosphere and the first-ever peek at its lower strata.
helvick
Oct 11 2006, 10:28 PM
QUOTE (Sunspot @ Oct 11 2006, 11:01 PM)
....this week said that data streaming from the Venus Express probe had provided unprecedented detail of the Venusian atmosphere ...
Well it's good to know that someone is getting "streams" of data. All the images the BBC used have been online for months - most are shown above in this thread and were posted here six months ago.
However it must be said that this article is one of the most informed we've seen on the mission since it started doing science in earnest and to save you all the bother I have extracted all of the information it contains that we did not already know prior to VEx reaching the planet.
QUOTE
But for now, scientists are happy to report that all the instruments are in good working order and beaming back massive amounts of data. "It's a treasure trove of information," said David Grinspoon, a participating scientist with the mission, "and we've barely opened the chest and looked in."
Thanks for that. I would note that it is my belief that the above is slightly incorrect as the PFS is still offline. I live in hope that my grand children will some day get to see this treasure trove.
djellison
Oct 11 2006, 10:30 PM
Well - stuff should start hitting the PDS soon....we need a slinted-type effort to process the whole damn lot in an easily viewable option.
Doug
Rakhir
Oct 13 2006, 01:06 PM
A new press release for VEX but just two images !
Complex meteorology at Venus
elakdawalla
Nov 9 2006, 07:16 PM
Two more images and one more movie have dribbled out:
Happy Birthday, Venus Express!Sigh. I'd give a lot to see them just release a daily or even weekly apoapsis image so we could watch the clouds move....I'm really not asking for anything fancy...
--Emily
MarkL
Nov 13 2006, 03:41 AM
Well it's a fairly boring mission from my point of view. We'll never land on Venus anyway. I've just put Venus Express on ignore since ESA doesn't seem to want to keep updates flowing regularly. Much more exciting stuff at Saturn and Mars. Where we might, one day, conceivably land a human.
Sunspot
Nov 13 2006, 09:48 AM
Anyone see the recent Sky at Night special on Venus Express? They only showed a couple of pictures, and they were all from the ESA website and ones we've already seen. And come to think of it, they didn't really say much at all about Venus Express science, certainly didn't reveal anything new.
djellison
Nov 13 2006, 09:54 AM
Yup - I was watching very closely.....did you spot the Victoria crater navcam pan.....anyho - very very little actually about VEX.....but to be honest, that's what I've come to expect from VEX - they had the platform to say "we're seing this this and this" - and said almost nothing.
Doug
ngunn
Nov 13 2006, 09:57 AM
QUOTE (Sunspot @ Nov 13 2006, 09:48 AM)
Sky at Night. And come to think of it, they didn't really say much at all about Venus Express science
Yes I noticed that. Either Patrick Moore has been sworn to secrecy or ther're not even showing him the stuff.
ustrax
Dec 14 2006, 09:46 AM
elakdawalla
Dec 14 2006, 05:23 PM
In case ustrax wasn't clear,
there is a new release showing surface details resolved by VIRTIS.
I wonder, could any of you folks who like playing with simulated views of the planets produce a better Magellan comparison image than the one ESA released? They used a horrible base map. The comparison should be a global view centered at 270 E, 27 S, according to the caption information.
--Emily
volcanopele
Dec 18 2006, 10:48 PM
Nice write-up about this on your blog, Emily. However, I think that the release image shows both the actual data from VIRTIS, as well as a simulated view of temperatures based on altimetry data from Magellan, not VIRTIS data corrected for altitude. so this release is more about showing how well surface temperatures correlate with altitude.
Phil Stooke
Dec 19 2006, 02:00 AM
Yes, the Magellan map is modelled temperature based on topography and some assumed lapse rate. The key here is to look for differences between measured and modelled temps, which might reveal hot spots - active volcanism.
And Emily - your map of the Venus hemisphere is - alas - wrong! You are looking at Ovda Regio, not Phoebe. You're about 180 degrees off. Mixed up east and west longitudes?
Phil
djellison
Dec 19 2006, 08:39 AM
QUOTE (Phil Stooke @ Dec 19 2006, 02:00 AM)
The key here is to look for differences between measured and modelled temps,
Or even the changes over time in the differences between measured and modelled - that would be more of a clincher.
Doug
edstrick
Dec 19 2006, 09:42 AM
The trick will be to minimize interference from variable cloud opacity and any specrtral color imparted to the surface emitted near IR filtering up through the clouds by varying cloud properties. The more data the accumulate, the more they will be able to cherry-pick data with the lowest cloud interference. For precise searches for thermal hotspots, they'll have to convolve the surface emissions with the blur-function of the atmosphere, and then the blur-and-sampling of the Venus Express observations before decisively detecting a thermal anomaly.
remcook
Dec 19 2006, 09:56 AM
QUOTE
But to me it looks like the second map shows even more topographic effects than the first. For instance, in the center of both maps is a bluish region, which overlies a region of high mountains called Phoebe Regio. In the right-hand map, its temperatures seem even colder than they do on the left side, so it would seem that the effects of topography have been accentuated rather than removed. It would seem I don't quite understand their topography correction.
some people already noted the thing about the 'second' image being a modelled map of topography. Just one note: in order to retrieve temperature, a correction is needed to account for topography. If you have high topography, you'll have less atmosphere in the way, so less atmospheric absorption. I think this is the correction you mention. However, the actual surface temperature is ALSO correlated to altitude, since the atmosphere is colder at higher altitudes.
elakdawalla
Dec 19 2006, 05:43 PM
QUOTE (volcanopele @ Dec 18 2006, 02:48 PM)
Nice write-up about this on your blog, Emily. However, I think that the release image shows both the actual data from VIRTIS, as well as a simulated view of temperatures based on altimetry data from Magellan, not VIRTIS data corrected for altitude.
QUOTE (Phil Stooke @ Dec 18 2006, 06:00 PM)
Yes, the Magellan map is modelled temperature based on topography and some assumed lapse rate. The key here is to look for differences between measured and modelled temps, which might reveal hot spots - active volcanism. And Emily - your map of the Venus hemisphere is - alas - wrong! You are looking at Ovda Regio, not Phoebe. You're about 180 degrees off. Mixed up east and west longitudes?
Ooopss.... no wonder I was having a hard time finding the spots on the ESA release on that globe. I apologize for the mistakes. Not my best work at all.
Thanks for the corrections, guys.
--Emily
scalbers
Dec 20 2006, 04:35 PM
QUOTE (Phil Stooke @ Dec 19 2006, 02:00 AM)
Yes, the Magellan map is modelled temperature based on topography and some assumed lapse rate. The key here is to look for differences between measured and modelled temps, which might reveal hot spots - active volcanism.
And Emily - your map of the Venus hemisphere is - alas - wrong! You are looking at Ovda Regio, not Phoebe. You're about 180 degrees off. Mixed up east and west longitudes?
Phil
Greetings,
Oooops, I wonder if this errant globe posted for a while in Emily's blog was the same one I had sent her last week or so? I had imported the Venus map that Emily and I had put together into Celestia. I now see there was a 180 degree shift in the way I had imported the map. So when I get the chance I'll try to make a new globe in Celestia - though it'll be a couple of weeks until I'm back to my computer and email. The previous globe I made was just of the radar reflectivity. I also have a shaded/colored relief map of topography on my web site that would also be of interest to compare with the VIRTIS data. If anyone has access to Celestia in the meantime, feel free to give these maps a try.
Phil Stooke
Dec 20 2006, 05:37 PM
The VIRTIS map from ESA is labelled with negative longitudes, with -90 at center. If you just enter 90 without noticing the sign you get your 180 shift. Curse the backwards rotation of Venus!
Phil
edstrick
Dec 21 2006, 08:06 AM
"... Curse the backwards rotation of Venus!"
I'm having fun thinking of worse.. how about a planet with an IMAGINARY rotation. (sqrt(-1))
We apparently have small riged-body asteroids with 2 spin axes, I think Toutatis is one. Does a tumbling spin, like an American Football.
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