I think I heard it mentioned during the press conference today, (I can't find it now), about Rosetta itself possibly landing eventually, similar to what NEAR did at the end of the main mission at Eros? Since it's not like there's anywhere else to go with the remaining delta-v left by the end of 2015, and sunlight levels and activity starting to drop after perihelion, and the low gravity makes the difference between orbiting and 'landing' trivial. The whole thing would weigh a kilo or two, right?
Obviously there's a few more pressing concerns right now, but it's something to eventually think about.
At some point Rosetta will run out of propellant for orbit corrections.
The mass of Rosetta at regular EOM should be 2900 kg - 660 kg - 1060 kg - 100 kg = 1080 kg.
(Start weight - propellant - oxidizer - mass of Philae, from http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=2004-006A)
The http://en.wikipedia.org/wiki/Surface_gravity of http://en.wikipedia.org/wiki/67P/Churyumov%E2%80%93Gerasimenko at 2 km distance from the center of mass should be
g = GM/r² = (6.672e-11 Nm²/kg² * 1e13 kg) / (2000 m)² = 1.668e-4 N/kg.
The http://en.wikipedia.org/wiki/Weight of 1080 kg is F = m a = 1080 kg * 1.668e-4 N/kg = 0.18 N.
0.18 N is the force of a mass of 18.37 grams in 9.80665 m/s² gravity.
The actual weight of Rosetta would be a little less due to inertial forces by the rotation of the nucleus.
To be more precise: The http://en.wikipedia.org/wiki/Centripetal_force for a radius of 2000 m and a rotation period of 12.7 h = 45,720 s is m r 4 pi² / T² = 1080 kg * 2000 m * pi² / (45,720 s)² = 0.0102 N.
So we are at 0.18 N - 0.01 N = 0.17 N for Rosetta's EOM weight, corresponding to the weight of a little more than 17 grams on Earth.
That's a model estimate, and may differ, depending on the actual landing coordinates.
They have already stated they want to follow the comet during 2016, as it enters the dormant state. They would need a mission extension for that.
NavCam mosaic taken on 6 November 2014, with Agilkia landing site on top of the top lobe:
https://flic.kr/p/p7NcbE
"rejoined" (forgot password) for this epic event- hopefully it will spawn a co-op esa-nasa cometary exploration program - especially good time being alive for following an historic and species first...
ADMIN: Post moved.
Deutschlandfunk says the comet's surface remind of corals... Interesting comparison but might lead to some misunderstanding...
"Coral reefs under the sea" is what Paolo Ferri supposedly said in a radio interview for HR-Info - which is where Deutschlandfunk took it from, among others. Interview isn't available online (yet?), so can't check it for certain.
Considering quite a lot of people aren't even aware corals are alive i think the extent of misunderstandings will be limited
NavCam mosaic of 17 November:
https://flic.kr/p/pbzwPQ
The long wait for an OSIRIS color image may be over:
https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/22395
The AGU abstracts are online and full of good stuff, and a very small number of them contain images, including this one.
Phil
The color mottling in that image is very interesting (other than obvious color fringes caused by rotation between frames), I wonder if that's real or an instrument artifact.
https://agu.confex.com/agu/fm14/meetingapp.cgi#Session/1556to present the results from the instruments of Rosetta.
Made a new animation of navcams draped over my shapemodel. This time with the november 17 navcam quad.
My shapemodel is becoming better with each iteration. The match between features in the images and the shape of the model is surprisingly good if I may say so myself
http://mattias.malmer.nu/2014/11/navcam-november-17/
I notice that Rosetta/Philae topics get (so far) about 1500 posts and 300.000 views. Wondering if this beat Curiosity around landing time?
Newly published Navcam images of the region, 2.59 m/pixel: http://blogs.esa.int/rosetta/2014/11/24/cometwatch-20-november/
ADMIN NOTE: Post moved from Philae topic to correct discussion.
Very nice animation Mattias, as always
NavCam mosaic taken on 20 November:
https://flic.kr/p/qbuGVV
The shadow of the upper lobe is slightly visible on the coma.
Yes. And the mottling seems very regular. Like a Perlin noice function...
The parts outside the area are quite nice. One could perhaps work a little on the registration of the images to get less fringing. But you can clearly see the colour of the surface change on the different terrain types. (Especially if you remove the overall red tint)
Looks like noise / low resolution data. Perhaps some channels are of much lower resolution.
Thing is, looking at the rotational state in each of the rgb components, it's suggestive that the source frames cover the entire body, not a case of a colorized greyscale image at the center. Very odd.
A strongly hue and saturation stretched (hence false-color) version of the colored OSIRIS image:
My bet is that the image has been intentionally degraded to make sure that it is not used by anyone to do any science.
It is just way to much low frequency noise in the individual channels and there seem to be almost no correlation between surface type and color.
The images from OSIRIS we have seen so far are very very nice. there seem to be no noise pattern of any kind in those.
If one instead looks at the areas outside the noise stripe one is treated to a much higher quality.
Is anyone interested in matching up the diagram of probable Philae landing zones with the recent Navcam images showing those parts of the comet?
The zones are just on the other side of the dark grey ridge. Our point of view is 180 degrees off from what we would need to spot Philae.
The jets are really multiplying now! Also, I think this is the first time the dark side has been visible silhouetted against the background coma - we've seen it before with Halley and Hartley-2 but not here.
http://blogs.esa.int/rosetta/2014/11/26/cometwatch-20-november-in-the-shadow-of-the-coma/
Phil
Just noticed -- actually just realized what I've been seeing for some time -- that the jets are primarily pointing toward the Sun, while a comet's dust and ion tails point away from the Sun. Can Rosetta observe the process by which the trajectory changes as they become tails, or is Rosetta too close to see that effect?
OK...
http://hubblesite.org/reference_desk/faq/answer.php.id=19&cat=solarsystem
Phil
My understanding was that it was the pressure of the solar wind that forms the tail(s). So heating on the sun facing side leads to jets towards the sun, which eventually are deflected by the solar wind to form the tail.
If there were no solar wind, particles in a jet pointing towards the sun would presumably get ahead of the comet rather than be left behind (at least prior to perihelion).
Edit: Phil beat me by less than a minute!
Thanks for the comments and for Phil's good link. The question remains, however, of what details Rosetta will be able to provide about the process changing jets emerging on the sunward side of the nucleus into tails streaming away from the Sun.
Steve M
Small grains should be more susceptible to solar wind and radiation.
The http://sci.esa.int/rosetta/35061-instruments/?fbodylongid=1639 should be well-suited to investigate this question in very detail:
GIADA should provide interesting velocity data. Look forward to more GIADA insights into dust particle trajectories since since http://blogs.esa.int/rosetta/2014/09/12/giada-tracks-the-dust-2/ of a few dust particles.
NavCam mosaic of 26 November. The rotation of the comet has been substantial in the twenty minutes that passed between the two lower images, resulting in artifacts in the stitching process.
https://flic.kr/p/phnrd6
1 December NAVCAM from 30.1 km
https://www.flickr.com/photos/lunexit/15766808390/sizes/o/
Beautiful. Thanks for sharing that. It's amazing to pan around that view. What a place!
Lovely mosaic eliBonora! The one on the ESA blog has a blurry seam, where the foreground and background limbs meet, that had me scratching my head until I saw yours
Here are a couple attempts at anaglyphs from the Dec 1st and 2nd NAVCAM images, made from the slices where the bottom two (foreground) images overlap. Some artistic liberties have been taken to account for areas which were shaded in one image and lit in the other.
My take on NavCam mosaics from 30 November to 7 December:
https://flic.kr/p/q3ANLy https://flic.kr/p/posnFR https://flic.kr/p/qhYF1G https://flic.kr/p/q5R936
The latest Navcam blog shows new - or apparently new - features in the neck. Here's a comparison between October and December images (December on the right). I would suggest a close examination of images would probably show more things like this.
Phil
Sure enough, here's a comparison between 24 September and 9 December with the new feature on 9 December noted. Differences in lighting and resolution are small enough that I think this is a real change.
Phil
(PS... must work on book... must work on book... aaaargh!)
I would guess the pit is a low profile feature that produces shadows only when sunlight is at a very low angle. Otherwise, the lack of albedo differences in the smooth material renders it invisible otherwise.
Of course, the very recent formation of a collapse pit would be pretty cool....
I don't think the lighting is sufficiently different for the pit to not show up in the earlier image. What you describe is always a possibility in this type of comparison, but I don't think it applies here.
Phil
If it's all real, and it sure looks like it is, this will set some significant constraints on the life expectancy of comets in the inner Solar System. Could be a huge mission finding.
Well spotted, Phil!!!
I spotted the second example, but it was the Rosetta blog:
http://blogs.esa.int/rosetta/2014/12/11/cometwatch-9-december/
which drew attention to the first one. I just illustrated that first one.
Phil
If the pits did form very recently, then the smoothing process must have been recent as well.
Might the marks be the result of some fragment landing back on the comet after being wafted up by some outgassing activity elsewhere?
Non-linear brightness stretched (about quadratic) and 8-fold saturation enhanced version of the http://blogs.esa.int/rosetta/2014/12/12/comet-67pc-g-in-living-colour/:
We have tried to pull out more color from the OSIRIS image, not because it 's what the human eye could see but because it's interesting to highlight the differences. Of course we can exasperate more and more but we have preferred to maintain a balance with a pleasant look.
https://www.flickr.com/photos/lunexit/16006339535/
Here's also a curious gif created with the three RGB channels splitted:
https://www.flickr.com/photos/lunexit/15820377179/sizes/o/
"Might the marks be the result of some fragment landing back on the comet after being wafted up by some outgassing activity elsewhere? "
That's exactly what I would expect for these specific changes.
Phil
Request to the comet gods: puff Philae out of its hole so it lands elsewhere, in the sun and upright of course.
Great to finally see the comet in colour! The original OSIRIS composite has greenish cast (common to raw images, it seems, judging by the Mastcam and MAHLI raw images), so I've used "Auto color" in Photoshop to normalise the colours, and then decreased levels to reflect its dark albedo. This also brought out some colours, without the need for enhancing saturation manually:
NavCam mosaic of 9 December:
https://flic.kr/p/q8cP7Y
Could it also be that the neck region is occluded by the two lobes so that less dust and other material contributing to the dark colour is able to aggregate on the surface as the comet travels through interplanetary space? Admittedly, I have little expertise in the science of comet formation so that might be nonsensical (ie. is the surface colour even expected to be due to such aggregation?).
NavCam mosaic of December 10th:
https://www.flickr.com/photos/105035663@N07/15845836397/
Focous on the surface change noted by Stooke in the 10 Dec 2014 Navcam image.
My study of changes on the North Polar Plain 24 September '14 to 10 December '14.
http://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Comparative-Series/i-XTTqqmM/0/L/compar_24sept_2oct_9dec_10dec-14_vent_activity-L.png
http://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Comparative-Series/
--Bill
NavCam mosaic of December 14th:
https://flic.kr/p/puRbyj
That's a quick and very dirty try to get a 3d visualization of http://blogs.esa.int/rosetta/files/2014/12/SCAN_MD_zoom.png as x-eyed stereo flicker, not really recommended, unless you need to know and are ready to risk some head-ache or sea-sickness, more an idea for someone who finds time do better:
Just to be clear, though, the "dinosaur egg" pictures were not from Philae, they were from OSIRIS. I'll do my best to describe them: imagine a cliff face. Now imagine, instead of the usual kind of striations you'd see in a cliff face, that it was instead made entirely of gumballs. Or maybe peanut M&M's, since they didn't seem quite spherical, but rather slightly non-spherical, but still distinctly round. All of a uniform size. The scale bar on the image was 5m long, and the dinosaur eggs were somewhat smaller than that; Sierks said 2 or 3 meters. It was wacky-looking.
Yep; kinda wild that those images are being guarded at the same level of secrecy as surveillance satellites...
Presumably an image of Philae on the surface, once acquired, will be released earlier. Surrounding details can be easily cropped out after all.
They said that images had been acquired in a sequence planned for when Philae should be in sunlight, but that the images weren't on Earth yet. I think.
http://wpc.50e6.edgecastcdn.net/8050E6/mmedia-http/download/public/videos/2014/12/029/1412_029_AR_EN.mp4 has been released with NavCam mosaics taken in November and December.
Informations on the making of this movie and files containing both the mosaics and the individual pictures are available http://blogs.esa.int/rosetta/2014/12/19/cometwatch-the-movie/.
They also provide SPICE data for each pictures.
They invite amateurs to do their own mosaics and movie : challenge accepted !
In the image information file, how is "rotation phase" defined?
After some work of stitching, here is my animation of the rotation of comet Churyumov-Gerasimenko. Full resolution is available https://www.flickr.com/photos/105035663@N07/16149519312/sizes/o/.
I'm working on https://www.flickr.com/photos/105035663@N07/16330253526/.
I have included 7 mosaics yet and I'm pretty happy with the result! Pictures between each NavCam mosaic are interpolated using a morphing software: MorphX on Mac.
Very nice animation. Much better then ESA original. Thanks for creating and sharing.
First NavCam image of 2015 :
http://www.esa.int/spaceinimages/Images/2015/01/Comet_on_1_January_2015_NavCam
Can't stop, rushing to class, but the newest image has lots of surface changes in it.
Phil
Some surface changes I've identified comparing it with the 9 Dec 2014 NavCam image. It looks like some of the 'ripples' (I am sure there's a better term) that were first seen in that NavCam image have been erased by surface flow. Many new such features have appeared, however.
Here are two close-ups, same features as Hungry4info circled - if you look carefully there are others as well. Also a third post which is derived from my earlier one but adds a third time step. The pits shown with arrows look like the same feature until you check carefully, and they are different.
I have searched other areas on the nucleus in vain, looking for changes there.
Phil
The illumination angles in these images appear to be similar, based on the shadows we see.
I think, Phil is (one of?) the most experienced experts in this field, and identifies textural changes much better than me. So if I'm unsure, I'm attributing this to my lack of sufficient experience.
In this special case, the central pair of images shows rather similar illumination. Some subtle features look rather similar (unchanged) in both images, such that I strongly tend to agree with Phil, that some deepenings show up in the right image, exclusively.
But you're of course right, that changing illumination needs to be considered.
Alléluia !! An image of OSIRIS !! Old (november 22) but spectacular :
http://www.esa.int/spaceinimages/Images/2015/01/Comet_activity_22_November_2014
Looks to me the main jet is made up of about 14 jets all combining together, awesome.
And now the daily NAVCAM image :
http://www.esa.int/spaceinimages/Images/2015/01/Comet_on_10_January_2015_NavCam
Look what happens when you stretch the contrast in the OSIRIS image: a beautiful silhouette at the bottom, and the shadow of the nucleus on the coma.
Phil
Cool. Is it correct to say that the jets appear to curve because material within them is moving radially outward from the comet, while the comet (and hence the jet source regions) is spinning?
I am amused that the first phrase in the blog entry is "In the first OSIRIS image release of 2015..." We're supposed to be getting one per week -- even the ESA bloggers can no longer conceal their exasperation about that!
I suspect we're not seeing the "lawn sprinkler effect" here - to see curvature in the jets you'd need the speed of the jet material to be not too much more than the rotation speed. I don't know what the expected order of magnitude speed for the jets is.
To me it looks more like we're seeing different (more or less straight) jets in different directions superposed along the line of sight. So one jet in one direction in behind, and other jets pointing in a bit different directions in front. You'd expect jets from separate vents to travel in somewhat different directions.
That's an annotated, brightness-stretched resized crop of http://blogs.esa.int/rosetta/files/2015/01/ROS_CAM1_20150110A.jpg:
The change of direction seems rather more abrupt than gradual. Is it possible that frozen particles in a conglomerate might finish sublimating in a puff, sending their inert carrier particle in an opposite tangent?
Break-up of some hydrated state? I couldn't rule this out, easily. But particles should be of very different size, otherwise we would see a fork.
I've also been considering electrostatic interaction (attraction / repulsion) with the spacecraft. But for this, the motion should be almost perfectly parabolic, which I doubt that it is.
Collisions with fast-moving tiny grains (less than 300 nm diameter to be invisible as individual particles) may be possible, too.
ESA's director general Jean-Jacques Dordain http://www.bbc.com/news/science-environment-30859411 his frustration and sympathies with the current image release policy of Rosetta (and other missions); but no signs of any changes coming soon:
Thanks, Gerald. For a 3 km radius, we have roughly 0.5 m/s rotation velocity, which is far smaller than hundreds of m/s. So indeed, for the near-thermal-velocity particles, it looks like we wouldn't expect to see curvature in the jets. Picture a sprinkler rotating extremely slowly...
I was wondering if interaction between the jets and the material of the inner comma may, by friction or ion interactions, tend to curve the tops of the jets as they are, initially anyway, tied to the rotation of the nucleus. The OSIRIS image from 22nd Nov seems to show some curving of the jets further from the nucleus. The very low densities involved would tend to make me think these effects would be rather small. The velocity of inner coma material relative to the surface would need to be known, Rosetta does have instruments to determine that, though.
Last NavCam mosaic: 10, 12 and 16 January
https://flic.kr/p/pTwGmz
https://flic.kr/p/qRfVAu
https://flic.kr/p/qRfVAu
This shows the same view of 2 November but under different lighting
(here in two versions https://flic.kr/p/pEDHFi https://flic.kr/p/pEY7qj)
As per the scientific results thread, 14 newly released OSIRIS images can be found http://www.esa.int/Our_Activities/Space_Science/Rosetta/Highlights/Comet_close-ups. Per https://twitter.com/BBCAmos/status/558346921002434561, the dinosaur eggs mentioned at AGU are here referred to as 'goosebumps' (pic 13).
EDIT 2x: Some more context in http://blogs.esa.int/rosetta/2015/01/22/getting-to-know-rosettas-comet-science-special-edition/.
http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2015/01/comet_from_8_km/15206382-1-eng-GB/Comet_from_8_km.jpg is OSIRIS at full resolution from 8 km - almost like standing on the surface!
If these are possibly raw images from OSIRIS, one explanation could be the shadow of lint that somehow got onto the surface of the sensor (assuming a conventional flat sensor, not push-broom--offhand, I don't know the architecture). Since this is likely a processed science image with known image defects cleaned up, then we could be looking at the shadow of a sharp shard that is pointed toward the camera, and whose top is blended into the background dust layer. I favor that interpretation, as anything stick-like on that surface is unlikely. But I sure think it looks like lint.
I've had no problems.
You can see all the same images in http://t.co/Gc7x5I9UNd.
Thanks! Yeah, it's been a continuing issue for me with the ESA websites. I may need to discuss this with my Comcast rep...
From http://www.nature.com/news/science-pours-in-from-rosetta-comet-mission-1.16777 nice images, names of the various terrains and graphical 3D models with VIRTIS data.
yeah, the shadows cast by that heck thing are all backwards in the http://www.esa.int/spaceinimages/Images/2015/01/Comet_from_8_km for that to be er..um..uh.. "something else entirely".. but the exposed chunk directly below it reminds me of the ubiquitous layered chunks at Gale crater.
Looking at it enlarged, I think it has all the characteristics of a small fiber on the sensor surface, particularly given the long focal length, which tends to project tight shadows from schmutz in the optical path. I'll be watching for it in any other OSIRIS images that have broadly smooth and light features in that quadrant. I'm surprised it has not been identified as a defect for standard pipeline processing as done for the Curiosity MastCam images that have known dust motes. Anyway, great photos--the foreground of that photo shows clearly a sort of gravelly texture at a centimeters scale.
"Geomorphological map of comet 67P", with names across the Egyptian mythology:
http://www.sciencemag.org/content/347/6220/aaa1044/F3.large.jpg
Nice overview of the info from the latest papers: http://www.bbc.com/news/science-environment-30931445
I'm having trouble locating a good global context image to show the location of the "http://www.esa.int/spaceinimages/Images/2015/01/Comet_from_8_km" photo. Can anybody here help me out with that?
(Sorry to keep talking to myself here)...the more I look at the OSIRIS images, the weirder some of them are. Many of the ones that have been resized are also posterized; the "http://www.esa.int/spaceinimages/Images/2015/01/Crack_extension_in_Hapi" one, for instance, looks like its color table was reduced to 16 gray levels before it was brought into a desktop publishing program for annotation, and when it was exported from there it was exported at a resolution not quite 5 times its original resolution. These images are really munged up
Do you think the "munging" might be one last attempt by the OSIRIS team to resist releasing their images, by releasing degraded versions? Or does it look more to you like these things are the result of processing by the people who actually published them? I mean, even at the best native pixel resolution, a lot of them look, I don't know, almost de-focused.
Also, am I right in assuming that all of the various releases of these images, including the ones released on ESA's own website, have the same issues?
Presumably the 'pipeline' isn't the same one that NAVCAM has been using for all the releases since arrival, so there's bound to be issues. Never attribute to malice, etc. etc...
@elakdawalla , I spent some time looking all over the small lobe NAVCAMs for the context of the http://www.esa.int/spaceinimages/Images/2015/01/Comet_from_8_km and couldn't find a match - quite some puzzle.
The image caption gives 15cm / pixel. Times 2048 is ~30m across ( if that refers to the public pixels rather than the originals ? ) , which is few NAVCAM pixels.
Interestingly Holger Sierks is not the Primary Instigator of the OSIRIS project.
Horst Uwe Keller led the team to built Cameras for space missions at the Max Planck Institute, first in Katlenburg-Lindau and now in Göttingen.
Keller was the driving force behind the Halley Multicolor Camera HMC for the Giotto mission.
After the one image success with this camera his team also was selected to built the two cameras on Rosetta.
Sierks took over OSIRIS after Keller retired.
Sierks has stated publicly at AGU that he was opposed to releasing the OSIRIS images, even to other Rosetta teams, giving as reason that others may make discoveries within them before his team.
@Explorer1 , all the OSIRIS images released so far have been very degraded and cropped, so by Occam's Razor this is unlikely a faulty image processing pipeline, Hanlon's Razor does not apply.
Ah, you found it, Machi! Thank you.
The "munging" results from these images being prepared for print publication -- they're cropped because they're used as illustrations for the Science magazine articles; they are resized because they're being taken through some sort of desktop publishing software for annotation before being exported to their present format. I'm not saying it's deliberate down-grading of the quality, it's just that these images are meant to be printed in a magazine and were never created with a digital device as an intended end product. But they're all we have to work with at this point.
I finished two videos using NavCam mosaics. Frames between each mosaic are interpolated with a morphing software. The gap between some of the mosaics was too big to obtain a single video.
https://www.youtube.com/watch?v=j64aqTWfSBI
https://www.youtube.com/watch?v=qCFEiR6oCeM
What are the long term plans for Rosetta's orbit? Will it remain at 30km as it gets closer to the sun?
[quote name='Habukaz' date='Jan 22 2015, 08:34 PM' post='217264']
What the heck is this thing?
It took some time to work this out, the shadows at first seem to be all wrong, but it does make sense if you look at it as two steps that merge into one at the near end. I have marked the edges of the steps on the close up below. I have also added a another context image for the OSIRIS 8Km image using the ESA region map.
https://www.flickr.com/photos/124013840@N06/16177086817/
https://www.flickr.com/photos/124013840@N06/16363047795/in/photostream/
Thanks Machi for the context. Another good view from side on can be seen in the middle of the head in this OSIRIS WAC image.
http://www.esa.int/spaceinimages/Images/2015/01/Comet_wide-angle_view
We already know about the February 14th fly-by as close as 6Km from the surface I believe. The current orbit will go out to 140Km before it dives back in towards the comet. A good chance to get close to those larger "grains" in their bound orbits.
Hmm, OK. That connection doesn't seem to have been made in the http://news.sciencemag.org/europe/2014/11/tensions-surround-release-new-rosetta-comet-data article I read some time ago, hence the confusion.
Honestly, I'm not expecting anything on the PDS from Rosetta's camera teams in 2015.
As far as I understood, Ptolemy measured all m/z up to over 100. Sample collection worked rather unconventional through the exhaust vent, which fortunately is located at the bottom of Philae, such that during 1st td a sample probably got accessible for analysis. That makes data analysis rather challenging.
Therefore I'd guess, that they'll be able to deliver EDRs, but I could imagine that RDRs may need some more time for a final release.
In the meantime it's likely that we'll hear from preliminary analysis results. (I'm hoping for within February to learn more.)
Yes Ptolemy is above 100m/z and COSAC upto 300m/z.
The sniffing is done through gas coming in through the exhaust in both cases. The COSAC exhaust is at the bottom of the lander while Ptolemys exhaust is at the top. The data analysis for a sniffing spectrum is complicated because you see all species at once and due to the 70ev ionization used you get fragmentation and even more peaks. But both Ptolemy and COSAC are in the middle of data analysis and I think the data will be published in the first round of the Lander articles. So you have to wait a little longer for the look on a nice set of organics in the data.
21 Jan CometWatch
seems to be a jet there!
https://flic.kr/p/q2kzvq
Yes, it's visible in the original frame. And it seems to be coming from the sunlit side of a pit.
This looks similar to the OSIRIS release image, where to me it also looks like the jet is emerging from the sunlit side of the pit (circled in my image), rather than the bottom:
Has anyone any more information about the "little white blobs" on the NAVCAM image posted today on the Rosetta blog?
http://blogs.esa.int/rosetta/2015/02/06/anuket-vs-anubis-cometwatch-31-january/
The blog post says
My take on NavCam mosaics from 16 to 22 January:
https://flic.kr/p/r3dj53 https://flic.kr/p/q7ann6 https://flic.kr/p/r1FTSq https://flic.kr/p/q8mVvN
https://www.youtube.com/watch?v=s3qflVyfCsk between 2 November and 16 January.
I'm working on the very impressive last NavCam mosaic!
Here is my take on the latest NavCam mosaic of 31 January:
https://flic.kr/p/r5qDEn
These streams of gas and dust are really impressive! We can even see the silhouette of the nucleus against the comet's coma.
Here our 31 Jen CometWatch
https://flic.kr/p/qMSBHG
Many thanks for the replies. Very much appreciated!
Regarding (some of) the dots being stars - as was pointed out by flug, the dots that are shown up against the darker background of the comet's unilluminated area can't be stars . But a commentator on Asterisk, the Apod linked discussion forum, madehttp://asterisk.apod.com/viewtopic.php?f=9&t=34418#p239307 for the somewhat similar Osiris image that was a recent Astronomy Picture of the Day.
My ability to work out what stars would be within Rosetta's field of view is inadequate to assess it.
BTW - I've posted ahttp://asterisk.apod.com/viewtopic.php?f=31&t=32292&p=239427#p239427 on the Asterisk board. (I've been a member there for longer than I have been here, and have been routinely contributing to maintaining the Rosetta thread in Breaking Science News.)
I think the detection of meter-sized fragments near C-G may vindicate Giotto's Optical Probe detections of "cometlets" at Grigg-Skjellerupp. opinions anyone?
This phenomenon of small fragments moving near the nucleus was also very clearly seen at Hartley 2.
Phil
http://science.nasa.gov/science-news/science-at-nasa/2010/18nov_cometsnowstorm/
Universe Today is showing a new Navcam image from Rosetta, Feb. 3. I don't see it posted on the Rosetta page, but it is a fascinating image. This is going to be a wild ride.
http://www.universetoday.com/118901/rosettas-comet-really-blows-up-in-latest-images/
It was posted on the blog yesterday: http://blogs.esa.int/rosetta/2015/02/09/last-waltz-at-28-km-cometwatch-3-february/
My take on the NavCam mosaic of 3 February:
https://flic.kr/p/r63a93
It may just be a function of the viewing angle, but, in the February 3 image, for all the world it looks like there are jets coming off of the near lobe of the comet pointed almost directly away from the camera, flowing parallel to the neck and then striking and flowing off of the far lobe. I can understand the striations on the underside of the neck leading up into to the far lobe, if that's what's happening -- they're the result of "wind" erosion.
-the other Doug
Looks to me like some shadowing effects to sort out with this interpretation.
This is a spectacular view!
I think that we may be seeing time-variability in jet activity. If we compare what appear to be sunward-directed jets from sunward-facing sides of pits, the jets seem to have changed over the interval between neighbouring frames - compare the arrowed features:
A composite of the two NavCam pictures of February taken more than 100 km away from the comet:
https://flic.kr/p/qTNWQ1
Flyby navcam's are up:
http://blogs.esa.int/rosetta/2015/02/16/cometwatch-14-february-flyby-special/
Some of those 'cosmic ray hits' are suspiciously large (from the zip file).
Some rather bright ejected grains, yes.
Fortunately none of the really big ones hit Rosetta.
Given enough time, one could figure out their trajectories and orbits; maybe arrange for a close look at one later in the year?
That paper said some might be as big as Rosetta itself, correct?
At present moderate activity level we still see probably two populations in terms of grain size. The freshly ejected grains resulting in the streaks on the Navcam images will be up to the centimeter range, whereas the distant grains in bound orbits may reach up to a few meters diameter comparable to Rosetta without the solar panels.
But who knows when the next outburst may eject large grains in the meter scale.
The distant large grains in bound orbits should be near a velocity of 10 cm/s (about 7 cm/s at 150 km distance) relative to the comet, such that if one really decides to visit one of those bound grains from some distance, it would be possible to aim almost straight to it. Better of cause would be a three-dimensional map of the bound grains by stereo imaging and trajectory estimates. I could well imagine, that the OSIRIS team is working on such a survey, particularly since they've numbered the grains in one of the papers. Such a survey would also make sense in order to compare bound grains before and after maximum activity to esimate the evolution of the bound grain population over longer periods of time.
I'd imagine that would depend on the size and mass of the lump, its velocity and where on the spacecraft it hits Rosetta. Also, a lump or clump could hit in a bad spot -- on the outer lensing of OSIRIS, say -- and leave enough material to degrade the imaging.
Fingers and toes crossed, nothing terribly untoward will happen. But I gotta think the mission planners knew they'd be running such risks when they planned extended operations inside the coma of an active comet.
An unplanned science interruption is probably not on the science team's list of priorities. Managing to close in enough to resolve some of them as more than just points probably is though!
It's funny that C-G as a miniature planetary system with moonlets (micromoonlets?) has gone pretty much unreported; even Phil Plait's recent blog post just assumes they are cosmic ray hits (to be fair, so would anyone after this many years of seeing raw images): http://www.slate.com/blogs/bad_astronomy/2015/02/10/rosetta_new_images_of_comet_show_it_outgassing.html
Some flyby's processing
https://www.flickr.com/photos/lunexit/15935505634/
https://www.flickr.com/photos/lunexit/16550376871/
https://www.flickr.com/photos/lunexit/15928651694/
Great pictures as usual, Eli. You don't forget the albedo, even it's useful for human perception of space objects, it's rare and difficult without colors.
.
The 2nd and third are awesome. Full of detail.
My take on the flyby mosaics:
https://flic.kr/p/rdoEX5 https://flic.kr/p/rdrqf3
https://flic.kr/p/qVZG7u https://flic.kr/p/qWZ5XT
And two close-up on Imhotep region from the 3rd mosaic:
https://flic.kr/p/rdvgam https://flic.kr/p/qWcqzv
Fabulous mosaics - thank you Eli and Neo!
Thanks to Eli and Thomas for the lovely mosaics.
I am fascinated by the right hand close up of the Imhotep region. The formations on the far side of the plain have a "glassy", sort of shiny appearance. This is certainly a phase angle effect, but for me it lends credence to the composition ratios suggested by the ESA teams. That is about 70% dust, 25% volatile ices and 5% organics. It looks a lot like rock, but the reflectivity is all wrong. Most of all, the way all the material appears SO eroded on a body with no atmosphere to speak of, no surface fluids either. This for me is the most clear evidence that 67P is made of material totally alien and incomparable to anything on Earth.
Great work with the mosaics. I can't help thinking that if we're getting images this good from Navcam, what will the OSIRIS images look like?
So what are we to make of theses layers seen in Phil's image and visible in Eli and Thomas's mosaics, as well as many other images over the last six months. This NASA article and the attached paper make interesting reading.
http://www.nasa.gov/jpl/rosetta/why-comets-are-like-deep-fried-ice-cream/index.html
The estimated porosity of 70-80% for 67P strongly suggests it has an inner core of Amorphous Ices. Recently the OSIRIS team suggested a layer of surface, as much as 20m thick, is lost during the weeks around Perihelion. The critical temperature mentioned in this article of 150K would thus move further below the surface and initiate the formation of new layers of "chocolate covered ice cream". In the process, the phase change would release considerable amounts of energy and a significant change in volume allowing sublimated gases and possibly liquids to collect below the surface in high pressure pockets, the Cryovolcanic equivalent of magma chambers. All sorts of mayhem could then ensue at that point. The oily organic boundary may lubricate, or even create, large area fracture planes just to add to the show. I have numbered some of the more readily discernible layers at Imhotep.
https://www.flickr.com/photos/124013840@N06/16387284287/in/photostream/
The previous orbit of 67P had a Perihelion twice as far from the Sun as the current one, surface loss would be much, much less, leading to thinner crystalline ice layers. Unfortunately for this idea the layers appear to be upside down. The thicker upper layers may well be due to various possible forms of resurfacing like Cryovolcanism, a large increase in coma fallout and dispersal of debris during major activity at Perihelion, all scenarios made possible by the recent change of orbit.
I wouldn't really rate this idea as a viable theory, but maybe some discussion might bring enlightenment.
Interesting paper, Sherbert.
I believe the fine layering is due to coma fallout that occurred during and after multiple perihelion passages (as you mentioned). The beds are probably not primordial or really ancient, since they have not been mixed up (time averaged) by eons of impacts. The regular jointing (barely visible) may indicate that they didn’t form in the very recent past (i.e. last few orbits or so; the smooth surface, on the other hand, is likely a very recent layer).
Perhaps there is a ‘'battle'’ between deposition and erosion. In other words, the particles are deposited as they slowly drift back to the surface after being expelled, while outgassing and surface disruption removes them again in places (see the ‘swept clean’ areas in some of the mosaics above. By chance, as in this case, there will be patches or areas of layering that manage to survive disruption. It kind of reminds me of the earth’s rock cycle in miniature -- with ancient basement rock, old strata, and recent sediment -- but with radically different processes in play (of course ).
I have to agree with you Gladstoner, layering due to deposition was my main thought until I read the NASA article. It is perhaps a too Earth centric view though. Sediments form consolidated, hard rock layers on Earth, in large part due to the Earth's gravity providing the high pressure to compress them, via the weight of subsequent deposition layers. The minuscule gravity of 67P, I would think, would be insufficient to compact the dust/gravel to form these seemingly solid, rock like, layers. Also this dust/gravel once at the surface, even more so once expelled, is virtually devoid of volatiles, so if the outer sub-surface layers of the comet are compressed dust and coma fallout, sublimation activity would surely be minimal. In my view, this rules out dust and coma fallout deposition as a large scale structural process.
Right from our first views of 67P in August, I have been convinced that the surface is predominantly a volcanic landscape. Until now I could not really come up with a regularly available energy source well below the surface to account for this apparent Cryovolcanism. An intermittent source from impacts was the best I could do. I may therefore, be clutching at straws, but pockets of pressurised, molten material, dozens, or hundreds, of metres below the surface created by the change from Amorphous ices to a more compact, lower energy, crystalline form, could readily explain many of the features we see at the surface as well as the expected kilometre scale, supersonic "jets".
I do like the "battle" between deposition and erosion idea as a predominant comet resurfacing process. It certainly helps to explain the observed, surprisingly, homogeneous colour of the surface layer. In the Northern "Duckiesphere" deposition appears to be in the ascendancy, in the "sunnier" South, erosion. In the equatorial region it seems fairly even, some dust/gravel, but lots of rubble, the energy flux not being enough to eliminate larger stone and boulder sized pieces from the surface.
I keep thinking the only significant source of energy is absorbed infrared conducting inward to dissociate the liquid glues holding together outcroppings of aggregates, and it would seem all the action is limited to the outermost onion skin boiling away as a layer of chunky grime, seeming hardly enough to do much in one pass, though perhaps plenty over tens of millions.
I'm wondering what kind of radiation environment may result during a direct CME hit and how much energy may that produce and at what distance below the surface could such energy be released?
it brings to mind (and i am completely out of my depth here) how reactors use boron to slow down the radiation enough so that it can interact, otherwise it shoots by and that energy is not captured.
One small correction here. Boron is used to capture neutrons in a reactor, stopping the reaction. It is carbon, hydrogen, deuterium, and/or oxygen that are the stuff used to slow them down without significant capture, increasing the reaction. And I think it's the latter that atomoid had in mind.
Regarding the cryovolcanos: This may need some adjustment, since inner heat is unlikely. Heating comes from the Sun. Water ice usually doesn't melt below 273 K within a reasonable pressure range (see http://en.wikipedia.org/wiki/File:Phase_diagram_of_water.svg). Under near-vacuum conditions, however, there may be some moderate pressure build-up at 220 K (between 1 and 10 Pa).
The main source for higher pressure potential comes from CO2, CO etc. (http://en.wikipedia.org/wiki/File:Carbon_dioxide_pressure-temperature_phase_diagram.svg) Virulent outbursts should therefore be driven by these highly volatile gasses.
See also the http://en.wikipedia.org/wiki/File:CO2HydrPhaseDiagram.jpg as an option.
I wonder if certain highly-volatile ices could become superheated even with the extremely low temperatures that one would expect within the nucleus -- even near perihelion. To me, that seems to be the only possible driving force for explosive activity.
Is it possible to estimate the internal temperature of the nucleus, or are there too many unknowns?
Hi Gerald. I am assuming the volatile ices contain a number of different molecules. Carbon Dioxide and Water being the most abundant it would appear from the data released so far. Yes vapour pressures would have to be very high and the energy released by the phase change from amorphous ice to crystalline ice substantial to allow for liquid water, but the presence of Methanol, Ammonia and other volatiles in the mix, which lower the melting point of Water ice, may well change the equation. Methanol and Ethanol mixing with Water is an exothermic reaction too to add a bit more heat to the mix. I also have no idea at what depth this ice phase change might happen. This would have a large bearing on the confinement of any evolved gases. No matter what the pressure, pure liquid Water can not exist below ~253K, so it is asking a lot. The other problem is the lack of pressure at the surface, especially over areas more than a few square metres. So I think its plausible, but a lot more information about the ice mixture and the effect the large amount of dust and the organics have on the possible phases of the volatile ices mixture would be needed.
Certainly the main driver of the gas pressure is likely to be Carbon Dioxide, it has no liquid phase and the change in volume from solid to gas is massive. Nitrogen expands a vast amount when going from solid to gas, but it would seem to be in short supply on 67P. Solid Nitrogen would only be likely in the very centre of the comet in the coldest spots. If conditions do occur that allow some sort of fluid state, I would imagine it would be infrequent and very short lived at the surface, but some type of molten or semi-molten material has flowed on the surface. The other possibility is some sort of plastic flow of this peculiar mixture that makes up the comet. That is a pure guess as I know next to nothing about the mechanisms of plastic flow. As you know I tend to deal in ideas rather than numbers and as I have already said, I am not sure it is a viable theory even without knowing many numbers, but it would explain many of the large scale features on the surface.
I'll leave it to the proper scientists to work out the details.
Some further thoughts on the possibility of liquids at or near the surface of 67P.
If one looks at molten rock, lava, on Earth as an analogy, its temperature is many hundreds of degrees higher than the ambient temperature at the surface, it does not freeze instantly and can continue to flow for many Kilometres. This often occurs in lava tubes, where a surface skin has solidified insulating the hotter liquid inside. Lava on Earth takes many forms depending on the chemistry of the rock and to a large extent on the amount of gas dissolved in the rock. There is the hot flowing version of lava, but also the slow crumbly, creeping version, various states in between and Pyroclastic flows. Different textures of material with different physical characteristics can be seen associated with possible Cryovolcanic activity on 67P, compositional differences and initial temperature conditions of the original molten, or semi-molten cometary material might account for this in a similar way. The high specific heat capacity and lower melting points of aqueous solutions also contributes to slowing the freezing process due to temperature. So the temperature at the surface might not be so much of a problem as I initially imagined.
The more problematic issue of very low pressure at or near the surface, still remains. The scenario, as imagined, is that at an undetermined depth, but reasonably assumed to be well below the surface, a layer of crystalline ice, made mostly of Water and Carbon Dioxide, but with many other volatiles within it, is formed by a phase change from Amorphous ices at some critical temperature. This releases heat energy, there is a decrease in the volume the ices occupy, creating empty space. This vacuum is immediately filled by the most volatile substances, Carbon Monoxide, Nitrogen and Carbon Dioxide being the primary candidates. These gases are confined by the previously formed crystalline layers above and hence compressed, increasing their temperature and pressure. At some point the local supply of these more volatile volatiles will be all converted, but such is the increase in temperature, the less volatile chemicals would start to sublimate/melt, such as Methanol, Ethanol, Sulphur Dioxide, Water, Ammonia and Methane. All the time these fluids are confined the temperature and pressure will increase, the volume of the pressure bubble increases, more material is eroded from the insides of the chamber. Space is now being taken up by a large percentage of incompressible solid, the dust which makes up around 70% of the cometary material. Thus we start a runaway, self sustaining, growing pressure bubble, within which the temperature is increasing, pressure is increasing, liquids are able to exist, in which gases can now dissolve, Carbon Dioxide being particularly good at this in Water. The material in the pocket can now be considered to be "hot" compared to the surrounding cometary material.
At some point containment is broken and a pathway to the surface and the vacuum is created. The "hot" dust/liquid/gas mixture, "frothy mud", will immediately travel towards the surface. If through narrow cracks, at extremely high speed, further increasing the temperature and pressure, eroding and collecting more material and gas along the way. Turbulence in these flows could be the cause of the "goosebumps" seen by OSIRIS. The highly visible result at the surface, would be your huge supersonic jets. All the time the pressure maintains a high velocity of flow, the temperature and pressure within the jet will maintain the phases of the material. Once confinement is escaped, dissolved gases will start to escape adding to the vapour pressure in the flow of material, the amount of collimation of the jet will then determine how long conditions within the jet can maintain a liquid phase. At the suggested supersonic speeds even a few seconds could mean liquids travelling great distances, Kilometres even, before freezing. That distance will get less and less as the pressure in the pocket is reduced and the size of the eroded caldera increases. Eventually the flow of "hot" material will reduce and the dust/liquid mixture will deposit around the caldera, soon solidify, to form a layered crater rim as the composition of the ejecta changes. Eventually the ejected material will fall within the created caldera rim to form a lake of "warm, fizzy, mud". This will freeze once its temperature and the rate of sublimation and dissolved gas escaping, falls below a level sufficient to keep the "mud" liquid. Eventually the surface layers above the pocket, depleted in solid ice, unable to maintain there own weight, will collapse into the now empty pressure bubble and form a pit or depression.
The longer containment below the surface is maintained the higher the temperature and pressure get, the bubble gets larger until it starts to distort the surface, creating a "pressure dome". More and more liquid could exist containing less volatile, larger organic molecules such as Ethylene Glycol, antifreeze. The heat would also travel down into the comet releasing more energy. At some point a catastrophic failure of the surface will occur and the pressure rapidly released over a large area, propelling large chunks of the surface in all directions. The dissolved gases rapidly expand creating the equivalent of Pyroclastic flows of dust, gravel, shattered cometary "rock" and gas which at their base would maintain a temperature and pressure sufficient to sustain liquified material, which is able to flow over the surface of the comet. In effect Cryovolcanic lava flows. The vast amounts of pulverised cometary material making up the dust cloud of the Pyroclastic flow would travel across the surface of the comet and deposit themselves over huge areas, the dusty looking plains of the Northern Hemisphere. At the top of Hathor cliff there is a distinct surface layer of lighter fine grained material many metres thick, which reminds me of the ash deposited at Pompeii from Pyroclastic flows.
The lack of any such activity up to now suggests this process, if it does occur, happens only at or soon after Perihelion, when the heat flux within the comet's surface layers is at it's maximum. At some time in the past, with supplies of amorphous ice existing closer to the surface, less energy from the Sun would be required, so even though 67P was more distant from the Sun, these processes could still occur, probably over larger areas of the surface too. The big depressions at Imhotep and Hatmehit may well be very ancient. The notorious variability of comet activity, could also be explained. Previously available volumes of Amorphous ice have been used up and until surface loss occurs to enable enough energy to reach deeper into the comet, vigorous activity will be curtailed.
I hope you like the story, its all basic geophysics, but it relies entirely on the assumption that sufficient heat reaches the postulated amorphous ices inside the comet and the overlying crystalline ice layers together with the proposed sintered ice layers making up the comet's "crust", have a structural integrity sufficient to maintain confinement for sufficient time. I am still not entirely convinced, there are one or two too many assumptions involved and entirely too much use of the word "porous" when describing cometary material, but that is the nature of speculation I suppose.
The comet 29P/Schwassmann-Wachmann 1 has periodic outbursts (~1 per year) despite its large perihelion distance of 5.76 AU.
http://en.wikipedia.org/wiki/29P/Schwassmann%E2%80%93Wachmann
http://cometography.com/pcomets/029p.html
The solar radiation at that distance is quite feeble, so there is something else going on with this comet, particularly since it has been close to its current orbit since at least 1908.
And, what you just postulated perfectly describes the formation of the dust and gas tails (the gas and small grains that achieve escape velocity) and the coma (the material that hovers around the nucleus and eventually falls back).
So, working it from the nucleus end, as you just did, results in what we see from a distance in the coma and tails. Good work!
-the other Doug
http://blogs.esa.int/rosetta/2015/02/27/cometwatch-the-challenges-of-a-close-flyby/: a new Navcam image from the close flyby, and an account that suggests we had quite a lucky outcome:
Temporary loss of star tracker only affects pointing right?
So there was really never any physical danger. Only risk of loss of science?
Gosh, an OSIRIS image, at 11cm/pixel: http://blogs.esa.int/rosetta/2015/03/03/comet-flyby-osiris-catches-glimpse-of-rosettas-shadow/.
Those jagged features are cliff edges.
There are some rocks that appear darker in the bright region (Heiligenschein). A difference in composition?.
The weird curved/bent feature from the 8 km OSIRIS picture released earlier has returned again at the exact same spot, and this time it is easy to see that it is an artefact.
I like how the OSIRIS/NAVCAM context image and even the shape model are available in uncompressed PNG form, but the actual high res NAC frame is a substantially compressed JPEG. Classy.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Hi-res: http://www.esa.int/spaceinimages/Images/2015/02/14_February_close_flyby
Rosetta has captured its shadow during the 6 km fly by. Resolution is about 11cm/pixel.
More info in german http://www.mps.mpg.de/3943019/PM_2015_03_03_Rosettas_Schatten_auf_dem_Kometen at the Max Planck Institute, which is in charge for the OSIRIS camera system.
Edit: I missed the link above. But anyways. really cool image of the detail in the Imhotep region. Picture is 228mx228m across. I really hope, the OSIRSI archives are released in a way, that is easyly accessable. When it is released...
It would involve strong assumptions to suppose that the compression was intentionally high to reduce what could be seen in the image. We've seen before oddly super-sampled images (and other resolution oddness recently with Dawn, eg) that were likely the result of press release requirements, and almost certainly not the choice of the science team. Similarly here, we know nothing about who determined the degree of compression or why.
Wow, look at this great false-color image!
Phil
http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2015/03/false_colour_comet_hapi_region/15307441-1-eng-GB/False_colour_comet_Hapi_region.jpg
That image shows the one meteor crater originally spotted by Emily. In the black of the lower right quadrant there seems to be a tinier crater that looks rather similar (the tiny hole on the ridge terminator, just below center here):
It has been noted elsewhere how colour images are so much easier to unravel and pick out patterns and features. This wonderful OSIRIS image is a perfect example. The deformation of surface layers by a pressure bubble forming well below the surface can clearly be seen on the far side of the valley, The resulting catastrophic failure and explosion has ripped a huge gapping hole in the comet. Molten material forced up from the interior has frozen and solidified as a dark igneous type material in a huge plug, totally different in appearance to the lighter surface layers.
The huge chasm extends the other side of the valley and is seen as the void above the Amphitheatre, where the darker igneous type material is seen again. Diffusion of dust through the porous interior to the tops of the lobes, seems to have left the axial regions richer in volatiles, increasing the size and likelihood of these gigantic Cryovolcanic events in the neck region. Less dust, less insulation, heat travels deeper into the comet. Thus a large trench has been blasted out around the axis of rotation to create the neck. Well its an idea, not sure how provable it is, but we seem short on explanations for the neck still, so I'm offering this as my suggestion as a further consequence of the Amorphous/Crystalline ice phase change energy source.
https://www.flickr.com/photos/124013840@N06/16185307724/
Can you help me confirm something?
I'd like to verify that we are only a couple days away from the latest possible date for 6 months worth of raw post-hibernation OSIRIS data to be made publicly available in the archives (or at least, the latest it is supposed to be made publicly available, assuming the statements made by ESA on its blog are true).
It was stated in June 2014:
"All Rosetta science instrument data have a proprietary period of 6 months, after which they will be publicly available in our archives" ( http://blogs.esa.int/rosetta/2014/06/25/comet-67pc-g-in-rosettas-navigation-camera/ )
This was confirmed in July 2014:
"With Rosetta, all data from its 21 instruments (11 on the orbiter, 10 on the Philae lander) are subject to a 6 month proprietary period." ( http://blogs.esa.int/rosetta/2014/07/16/access-to-rosetta-data/ )
Two months ago, I inquired on ESA's blog about why PSA didn't yet contain any post-hibernation OSIRIS data, despite the instrument having been returning data for well over 9 months. ( http://blogs.esa.int/rosetta/2015/01/12/cometwatch-6-january/#comment-322770 )
I was told, at that time, that "the release of science data that is on a six-month proprietary period is made six months after the end of the previous six month period", meaning that the actual longest time there could be from acquisition to release was 12 (6 + 6) months, and that the release would contain all of the data from 12 months prior to release, to 6 months prior to release (so, a six month chunk of data, ending 6 months before it had to be released). I was slightly disappointed to find out the wait time was really about 9 (+/- 3) months rather than "6 months" being the longest that teams could hold the data, but at least I'd been informed of the real maximum delay between acquisition and release (12 months), so that didn't really bother me. I never expected (though I had hoped for, of course) an automated 6-months-behind stream anyway. Storing the data in 6 month chunks and copying the previous one into the archives when the current one is finished, is certainly easier (plus the teams get the additional benefit of making the proprietary period of 6 months last 9 months, on average ).
I remember reading a comment that a person made on this forum, where that person said the 6 months started on the date Philae landed. I don't believe that person explained how they came to that conclusion, and it's a conclusion that seems, at least immediately, inconsistent with statements made by ESA on their blog, and since the mission lasts longer than 6 months after the landing, the data could not possibly all be released 6 months after that point, so I'm inclined to disregard that comment, at least until I find anything that explains how that conclusion may have been drawn.
It's also possible that that person had inside knowledge of the release cycle and was simply stating that one of the 6 month periods ends on that date, giving them 6 months from that point to make the data from that period publicly available. If that be the case, however, then you can substitute this entire post with a different question, which would be: if they chose that date as the end of one of their 6-month cycles (12 May 2014 to 12 November 2014), then they would have had to release all of the data from the previous cycle (end-of-hibernation to 12 May 2014) by that date, so where is it? I'm not aware of that happening, and the PSA doesn't show any OSIRIS data from end-of-hibernation to 12 May 2014, so I'll assume for now that what ESA has been saying on their blog is true instead.
I know OSIRIS resumed producing data at least as early as 20 March 2014 (a couple days short of a year ago) based on a press release from Max Planck about OSIRIS ( https://www.mps.mpg.de/3323535/PM_2014_03_27_Rosetta_A_glimpse_of_the_comet ) that says "This image taken with the Wide Angle Camera on March 20 shows a wide field 25 times larger than the diameter of the full moon."
I also know post-hibernation OSIRIS data has not been included in any data release so far (that I'm aware of), and given that post-hibernation OSIRIS data has been accumulating since at least one year (minus a couple days) ago, I can conclude that the latest the first 6-month batch of post-hibernation data would be released is 20 March 2015 (or earlier, if OSIRIS resumed returning data earlier than 20 March 2014). Additionally, I can conclude that the OSIRIS team hasn't opted for a release cycle shorter than the 6 month maximum (if they had, then the first set of post-hibernation OSIRIS data would have already been released), so the imminent data release, a couple days from now at the latest, must be a release that includes 6 months worth of OSIRIS data.
I don't believe I've made any mathematical errors, so that should be correct. I was wondering if anyone can confirm that all of that adds up and that we should expect to see all raw OSIRIS data from 20ish March 2014 through 20ish September 2014 released in the archive by the end of this week, or next week if it takes them a couple days to get the data into the archive for some reason (they are engineers, not network storage specialists, after all).
Thanks
I can confirm that it's six months after landing, or May 19. http://www.planetary.org/blogs/emily-lakdawalla/2014/07291014-rosetta-update-long-journey.html
That being said, the odds of the OSIRIS team actually complying with this requirement are pretty much zero.
Not much of a story -- first data deliveries from missions' main science phases are often delayed, the more so when it's a team that has been reluctant to share data. Even without that, first data release delays do happen on many missions for benign reasons -- the team's busy doing science on their first real data, so archiving is a much, much lower priority. And then there's the team personality. It's not just OSIRIS we're waiting for, remember, it's also ROLIS and CIVA.
At least we'll have NavCam!
The NAVCAM pictures at 10km are already quite stunning, so I will be very happy to see all of them.
In other news, it looks like 67p is http://www.bbc.com/news/science-environment-31965458. The previous perihelion passage had the opposite effect, although a spin up later might of course still be in the cards.
Lots of new Navcam images are now available at the Rosetta image archive:
http://imagearchives.esac.esa.int/
Including Earth and Mars flyby and CG approach.
Phil
First NavCam mosaic taken during flyby of 28 March:
https://flic.kr/p/qXC9yx
Levels adjusted to show jets of gaz and dust:
https://flic.kr/p/rA6Jta
Scary times for Europe's comet-chaser Rosetta
Europe's pioneering probe Rosetta battled breakdowns with navigation and communication with Earth after it ran into blasts of dust and gas from the comet it is tracking, mission control said Thursday.
source: http://www.spacedaily.com/reports/Scary_times_for_Europes_comet-chaser_Rosetta_999.html
ADMIN EDIT: No need to post the entire media release when members can read it at the original source. A headline and teaser is sufficient.
Here is the second NavCam mosaic taken on 28 March:
https://flic.kr/p/qZkX86
And a zoom on Hapi region:
https://flic.kr/p/rDNaBv
The third NavCam mosaic taken on 28 March:
https://flic.kr/p/rZTCpW
Levels adjusted to show the jets:
https://flic.kr/p/s3bQAT
Thanks Neo for posting all these mosaics - very much appreciated!
NavCam mosaic taken from a distance of 137 km of the comet:
https://flic.kr/p/rLHa9L
Levels adjusted to show jets of gaz and dust as well as the shadow of the largest lobe on the coma:
https://flic.kr/p/r7u99r
This image appears to show the south pole of Churyumov-Gerasimenko in detail better than I have seen before, thanks to reflected light off the larger component.
http://www.esa.int/spaceinimages/Images/2015/04/Comet_on_25_March_2015_NavCam
http://www.facebook.com/mattias.malmer.5 created this great tool to visualise Rosetta's view of 67P. Image updated every 10 minutes.
http://mattias.malmer.nu/rosetta-now/
Rosetta's comet throws out big jet
http://www.bbc.com/news/science-environment-32380793
More details http://blogs.esa.int/rosetta/2015/04/20/osiris-catches-activity-in-the-act/
(Always best to get as close to the horse's mouth as possible.)
Interesting that this jet comes from a surface in shadow. It also occurs to me that some of the first jets observed came from the shadowed parts of the neck region.
Is there possibly a mechanism working here that would cause jets to break through more often when the surface is shadowed? Or is it more likely that the new jet actually started while that region was sunlit and we only saw it after it went into shadow?
The heat pulse delivered to the surface each day will take some time to propagate down to the level where there are still volatiles to sublime. I don't see any mystery in the jet first appearing at night.
This one appeared within minutes before local dawn as I understand that Rosetta Blog post.
My complete layman hypothesis:
Local volatile depot within the comet is heated and expands; the interior of the comet consists of voids connected through ducts and cracks between material that the volatiles expand through; on the sunlit side, thermal expansion of the comet material partially closes off these microscale ducts, leading to the expanding volatiles being ducted preferably towards the dark side (or rather: increases friction between comet material particles, thus making it harder for escaping volatiles to "push" them aside).
The microscale ducting would be what shapes the jet velocity and extent and the material taken up by the jet is material taken along from the duct surface once the jet gains sufficient drive. The "heated volatile bubble" escapes through such a duct in a timeframe dependent on its size and heating profile within the comet; short jets would then come from relatively isolated reservoirs quickly exhausting themselves, with the larger jet there may be a ducting mechanism connecting multiple (or many) reservoirs within the local comet area.
Such a mechanism should create jets preferably on the not-yet-lit side near the terminator or in other unlit areas nearby lit areas, such as deeper craters or behind cliffs, as observed by Rosetta.
In regards to the last two posts, I have heard that geologists refer to the temperature pulses as 'waves' of thermal energy propagating downwards, and that its possible to use that temperature profile and extrapolate record of average temperatures going back decades or more, but i wasn't able to find much information on how fast these 'waves' are expected to travel by googling around.
Assuming this is mostly conduction it depends upon material/density to determine the timespan, with the comet being somewhat uncertain to characterize along those lines unless these current outbursts, if applicable to such an approach, can be used to characterize a model profile. Its also hard to characterize whether thermal expansion should tend to be maximized at these thermal pulses as well, thus working counter to 'seal off' any escape cracks leading from the very areas that are subjected to sublimation.
So assuming that residual thermal waves should eventually propagate to the very center and presumably least outgassed portion of the comet at some point, however long that may take, if thats an extended period, we may see significant outbursts long after perihelion.
I'm wondering whether there might be a possibility for this new jet to have originated on the sunlit portion of the comet. The obvious interpretation of the image is that the source of the jet is on the shadowed side, and once the jet has travelled far enough out it gets into the sunlight and so is visible. For this to happen the jet clearly has to travel out of the comet's umbra.
But another idea is that the jet originated in the sunlit region around where I put the black dot:
Notice that in the blog post they speculate that the jet actually originates from a sunlit face of a cliff/outcropping. It's just that due to the viewing geometry Rosetta can't see this sunlit area.
A hidden sunlit area seems harder for me to visualize, given the relatively low phase angle. Perhaps this can be explored with Malmer's shape model?
I took the timestamp and generated the viewing geometry and direction of the sunlight from SPICE data.
I then let this planar surface catch the shadow of the comet and moved it around until it had was lit as the little jet in the OSIRIS frames.
That gives us a reasonable lock on the location.
Really nice, Malmer. To answer scalbers' question, I can't see any sign of a cliff or outcrop near Malmer's source of the jet that's in the sun. And at earlier times the sun was even farther from that source location.
The sun did not hit the "underbelly" of the duck until about one hour and 15 minutes later. And that area had been in shadow for five and a half hours or so.
Hmm. All this may be telling us something about the thermal inertia of the comet as well constraining things like internal structural models and volatile composition/mix.
All in a very coarse sense, of course, but these are the sorts of key observations expected from Rosetta.
Internal plumbing? A pathway through the lobe, heated at one end, losing material at both ends?
Anyway, enough of such speculation - it's time to go nuts:
http://blogs.esa.int/rosetta/2015/04/29/major-release-of-navcam-images-800-to-30-km/
Lots of new Navcams from as low as 30 km.
Phil
today is one of those rare days we are treated with am OSIRIS release
http://blogs.esa.int/rosetta/2015/05/18/osiris-spots-boulders-in-balancing-act/
Another OSIRIS release - a really nice one of jets emerging from shadows:
http://blogs.esa.int/rosetta/2015/06/08/sunset-jets/
and a Navcam view of the southern hemisphere:
http://blogs.esa.int/rosetta/2015/06/09/cometwatch-1-june/
Still lots going on with Rosetta!
Phil
http://i.imgur.com/SpSU18G.png is a rough guide on where those jets are on a NAVCAM image from back in October. The pink line shows that maybe one of them have its origin in a small depression in the dust layer. Emphasis on maybe. I think the large jet and the potential origin shown with the cyan line is also worth taking a look at. I'm curious if the "dunes" that goes towards the right is formed by that jet. http://i.imgur.com/M5eUKCZ.png of the area. The yellow arrow is only pointing at the general area of where some jets seemed to be. The cyan and pink arrow once again points towards what might be actual sources. It's easier to see the dunes I were talking about at this angle as well. I wish to underline that these are all just crude guesses.
The original NAVCAM images are ROS_CAM1_20141008T021835_P and ROS_CAM1_20141008T140825_P that were recently released on the http://imagearchives.esac.esa.int/. Credits: ESA/Rosetta/NAVCAM – https://creativecommons.org/licenses/by-sa/3.0/igo/ and ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Good work DoF. Just finding some good alternative views of the right area helps a lot. I would tend to agree with the pink source site. It looks like it might be a source established on the previous orbit, the loss of volatiles from below the surface has created a depression. The area of the yellow jets seems about right too. Any jet source must, because we can see it in images, have a source of dust. It follows sites of bright jets are going to be covered in a large supply of dust. The source of the jets, the reservoirs of volatiles powering the jets, are below the surface, their shape and the escape routes to the surface are hidden.
In the microgravity of 67P the effect of capillary action on fluids becomes a significant determinant for how they behave and move. See NASA's microgravity coffee cup. With this in mind, some possibilities for discussion.
The evidence is that there are no large amounts of volatiles at or near the surface, they have sublimated away. Large amounts of volatiles are leaving the comet, so they are coming from below the surface and one way they could get to the surface, once the Sun's energy is sufficient to reach them, is by capillary action through the porous material and tiny cracks within it. During the long cold 67P winter some volatiles will freeze, most importantly Water, to seal off these cracks and fissures allowing pressure to build up below as the energy from above seeps deeper into the comet. Spring arrives, the comet crosses the ice line, the ices in the subsurface tiny cracks and pores, sublimate and the pressure from below is released, gas is pushed by pressure and dragged by capillary action to the surface. The deeper the pocket of volatiles is buried the longer it takes the route to unfreeze and the longer it takes for the Sun's energy to percolate down to them. In the neck area the depth of any volatile pockets is limited and together with it being a cold trap for condensing material from the coma, makes it the most likely area for the first jets.
If an aggregate of planetesimals of variable composition is how 67P initially formed, variously sized, volatile rich packets, would be randomly spread throughout the comet and would presumably have a general "potato" or "dinosaur egg" shape. What is left behind when all the volatiles have gone, a large pile of dust and a roughly spherical empty space. As the entire surface slowly erodes, several hundred metres was estimated as being possible by the OSIRIS team, these empty spaces and their lake of dust collected in a basin at the bottom, are exposed at the surface. A familiar formation on the surface, some showing evidence of collapsed roofs. The original volatile rich planetesimals also aggregated with variable composition, so boulders of more refractory materials are likely to be found within. These get left behind resting on the lake of dust, example Cheops and the rocks on the floor of the Imhotep depression, which themselves hint at being aggregates of smaller boulders of variable composition cemented together by an ice and dust mortar formed on the surface of each planetesimal in the same way as on the surface of 67P. This seems a fundamental construction technique on the comet, from the nanometre scale to the Kilometre scale and leads to that same diversity in scale in the appearance of a number of common visual features, the "horseshoe" shape for example.
Before sublimated gas from below can escape to vacuum, it must get through the dust layer. We have seen from Rosetta's dust collection, this is likely to be made of extremely fragile aggregates of micron sized dust particles, which offer even more scope for capillary effects to take over. The aforementioned coffee cup uses capillary action to create a self sustaining flow/stream of fluid in microgravity, as long as the astronaut keeps allowing the fluid to run into their mouth, the fluid will flow until every last drop leaves the vessel. This would suggest that the dust/gas interaction forces the fluid gas into micro sized streams, which combine at the surface to create a broader collimated stream, its direction determined by the vector of the force from the gas pressure below. Not all the energy in the gas column comes from the Sun's energy and the expanding gases. Capillary action still works in the dark, at least until the subsurface micro cracks freeze, closed again. Super volatiles like Carbon Monoxide, Nitrogen and Carbon Dioxide may well keep a small percentage of routes to the surface open and still escape at night or when the surface is in shadow, as seen in the ROSINA data.
Pressure from gas build up in volatile rich reservoirs below could lead to jets then, but simple diffusion through the porous comet material and the pressure gradient created by the vacuum at the surface, will also allow sublimated gas from widely dispersed, un-concentrated volatile sources, to move towards the surface, only this time with far less energy and with a more random set of velocity vectors. Capillary action in such low gravity would act in all directions, not just perpendicular to the surface, moving the tiny dust particles along with it. The dust layer acts like blotting paper for the sublimating gases, capillary flows dispersing the gas in all directions out into the dust layer. Pour a liquid through filter paper and it exits as a collimated stream.
In effect, because of the micro, even nano, sizes of the dust particles, the gas/dust mixture takes on the properties of a fluid, a fluidised bed, which is just heavy enough to largely remain on the surface. A number of comments have been made that the dusty plains look like seas and we have seen dunes and ripples in the dust as if it were behaving as a fluid. A percentage of gas will attain escape velocities sufficient to carry dust a small way above the surface. Once 67P crossed the ice line the halo of ejected dust all over the surface started to become visible. In the latest images that wispy halo has become a solid curtain tens of metres high, wherever there are areas covered in dust, where the increasing energy from the Sun is releasing larger quantities of dispersed volatiles with greater energy.
Capillary action/surface tension in microgravity has been intensively modelled in recent years, how fluids behave in space systems has become critical, fuel flows, hydraulic systems, lubricants and human environment systems, all need to take account of this effect. Can those equations and models be adapted to the surface environment of a comet? Constraints on particle sizes in the dust, its mechanical properties and energy flux figures are available from the ROSETTA and PHILLAE data, so one might hope the challenge is taken up. This represents a possible model for, very low energy, long time scale, erosion processes, akin to those performed by wind and water, on Earth. Such long timescale erosion is clearly taking place on the surface, the uncanny resemblance to eroded "rock" on Earth has been evident right from the first images of surface formations.
The numbers and models may show such fluidisation of the dust layer is not possible via this mechanism, but I am sure some outcomes are expressed in the topology of the surface. Of course it could be just another of my crazy theories, but maybe it will plant a seed in someones mind who knows a lot more about fluid surface tension in microgravity than I do. :-)
Not sure, what you mean with "fluid". A dust gas mix can behave similar to a fluid in some aspects.
But a true fluidized gas in the cometary subsurface doesn't appear likely due to low pressure; water (https://en.wikipedia.org/?title=Triple_point#Table_of_triple_points pressure 611.73 Pa), CO (15.37 kPa), and CO2 (517 kPa) are ruled out as fluids; ethanol (0.43 mPa at 150 K, according to the table) might be a feasible candidate, but its abundance is too low.
You would need such a fluid phase for https://en.wikipedia.org/wiki/Capillary_action. If interpreting a gas/dust mix as a fluid, its surface tension would be too low to cause relevant capillary forces, since https://en.wikipedia.org/wiki/Van_der_Waals_force mostly responsible for https://en.wikipedia.org/wiki/Surface_tension reduce rapidly with the distance between dust grains. But you need this distance between the grains to make them behave remotely similar to a liquid.
The gas phase shows https://en.wikipedia.org/wiki/Diffusion with probably https://en.wikipedia.org/wiki/Effusion as a special case.
Edit: There might be a scenario with capillary forces involved: Provided the crust of the comet turns out to be enriched in complex organics, they might show a tar-like behaviour, i.e. some softening under solar illumination, gluing dust particles together. This gluing might involve capillary forces. But that's rather speculative.
Impressive match between the shape model and OSIRIS image. The partly shadowed jets in the center look to be pretty close to Philae's location, if Philae is where we have been thinking.
Speaking of shape models-- what is the best 3-D Printing template/file available today? I'd held off having one of the early 3D files printed, waiting for them to mature.
Great that we've found Philae, it looks like she landed in rough terrain. I was hoping that this wouldn't turn out to be another "Elvis Sighting"...
--Bill
Thanks for your thoughts Gerald.
A gas is a fluid and as I understand it, can be subject to capillary forces. There is vapour pressure from the sublimating gas below which is increased when the gas is forced into a smaller volume, inter molecular forces and viscosity then become significant factors in the gases behaviour and it assumes many of the properties of a liquid. The narrow channels required to achieve this are on the molecular scale, but the evident porosity of the solid looking comet bulk material suggests this is a realistic scenario. The spaces left behind by already sublimated ices being the obvious mechanism by which such channels could form. The number of such channels would be dependent upon the ratio of the different volatiles and a comet's orbital and seasonal configuration. An explanation for apparently random, or regular, fluctuations in cometary activity maybe?
The possible fluidised gas/dust mixture at the surface is a whole different ballgame. This I imagine might behave more like aerated flour or cement dust, the reduction in friction between the particles from the gases percolating through it, giving it some fluid like behaviour, in particular the ability to mix and flow. The depth and permeability of the dust layer together with any cohesion provided by "sticky" organic molecules is probably key to the extent of any fluid like behaviour. It is clear from the activity we have seen that the vast majority of gases reaching the surface, leave it, carrying varying amounts of dust along with them, but I still think random diffusion and micro-scale capillary action would disperse the gases and saturate the surface dust layers as part of a dynamic equilibrium, at the very least leaving each dust grain with a boundary layer of gas molecules surrounding it.
The freezing of this gas/dust/organics mixture creates the solid material visible on the comet. Seasonal, orbital and diurnal temperature changes combined with coma fallout seem to be the basis of a sedimentary deposition scenario for which there is considerable visual evidence on 67P, the ROLIS images at Phillae's final landing spot for example. There has to be some mechanism whereby the ices, dust and organic material are thoroughly mixed and then deposited as layers to form the comets visible solid material and this is a suitably cyclical, long timescale and scalable mechanism that is a plausible fit. It of course remains for others with greater knowledge and access to the evidence to embellish or eliminate.
Sorry Malmer, I couldnt help it.
Now please back to the science
P
Yes, back to the sci - no, there's just time for this latest bulletin - lander spotted at last:
LOL
Gosh, I so love this forum.
now the question is
dose only one of those have BLUE plasma and gasses shooting out ( mouth)
or
do both have blue plasma and gasses (mouth and vent)
I love that visualization Malmer, you've really done great work. Too bad my desktop is so old by now that it can't really deal with your 3d model, otherwise I'd like to play around with it a bit more. Could I bother you with rendering a version that's the same as the middle render (i.e. where you try to match the OSIRIS image), but with the light direction changed so there wouldn't be any shadows in the area? Because it's the same angle it'd make it easy to overlay the OSIRIS image to better see where the visible parts of the jets area in relation to the underlying comet.
As for scalbers, you got the position of Philae a bit wrong. Basically from this viewpoint if you start from the centre of the Hatmehit depression and go directly left that's where you should find the lander, it's not at the same place as these jets.
Thanks for the clarification DoF. I think I was using some poetic license by saying "pretty close". It is in the same general part of the comet and perhaps close enough for Philae to see them (in the eastern sky jutting above the right edge of Perihelion Cliff)? Maybe it's around 60 degrees azimuth between Philae and the jets from an imaginary viewpoint at the center of Hatmehit.
The neat thing is that this could be a testable hypothesis.
Rosetta mission extended.
http://blogs.esa.int/rosetta/2015/06/23/rosetta-mission-extended/
I made a montage of 18 NavCam pictures taken between 28 March (top left) and 5 June (bottom right) drawing inspiration from what was done by ESA.
Contrast was increased to show streams of dust and ice particles.
https://flic.kr/p/vj8VWQ
It's entirely possible that I'm just crazy, but it seems to me that the latest release of NAVCAM images happened silently this week.
NAVCAM images for "Escort Phase 1" from 2014-11-21 to 2014-12-19 appear in PSA (and in the NAVCAM image browser), apparently deposited on 29 June.
I don't see a blog post about this or any mention of it anywhere. Did I miss something?
ftp://psa.esac.esa.int/pub/mirror/INTERNATIONAL-ROSETTA-MISSION/NAVCAM/RO-C-NAVCAM-2-ESC1-MTP010-V1.0/
http://imagearchives.esac.esa.int/index.php?/category/66
It was on the official Twitter feed; presumably that's more well-read?
Speaking of data releases...
It has also been mentioned here, in a number of different contexts regarding ESA mission scientists and their contributions to the PSA, that they are not always made in a timely manner.
AIUI, there is little in the way of enforcement of the submission deadlines, and from observation, they seem to be recognized more in the breach than in reality.
In other words, while the data should get there eventually, don't get too upset if they aren't submitted to the PSA right on schedule, there is precedent for such submissions to run significantly later than the scheduled dates. And that's about all I can really say, here. Though I'd love to hear from Emily her feel for the timing. She talks to those people one heck of a lot more often than I do...
-the other Doug
http://www.unmannedspaceflight.com/index.php?showtopic=7266&view=findpost&p=194406
UMSF community knew almost immediately about Vesta's data in PDS. But as only few of us processed those data so it wasn't so visible.
Another problem is that all images from Dawn are strictly speaking scientific (for mapping purposes) and there is no "kodak" moment
and because of that images aren't so catchy.
I realize that we have seen many subtle changes in many surface features since Rosetta arrived at 67P C-G. However, with the comet moving ever closer to the sun, and the ever increasing activity, has there been any noticeable reduction in the comets size? Or is it just that the losses are just too small, or maybe not easy to measure using the images that have been released so far? Apologies if this is a less than smart question, but I was just curious.
I think the losses on the northern hemisphere which we have been observing most of the time until now will not be too drastic. The southern hemisphere i think will be a different story... we have only seen a few illuminated images of that part of the nucleus, but at least to me it seems like it has been heavily eroded away (it is somewhat flattened). I think there is actually a paper by the OSIRIS team who predict up to 20m surface erosion on the southern hemisphere...
http://blogs.esa.int/rosetta/2015/02/09/seasonal-forecasts-for-67pc-g/
Btw, i added malmers shape model to my small webgl application (works best with chorme and to a lesser extent with firefox... and i am not 100% sure i got the comet rotation right )
http://www.googledrive.com/host/0B_Y5O4C6aiKmfktCSlJEb2N1d2h0WElIcEs1R081OXdfUS01MFV4Ukk4RGFGUllPMFNZZms
currently there is spice data for as far as July 15th. Rosetta seems to keep in its scanning pattern for contacting Philae.
from " h t t p : / / w w w .googledrive.com/host/0B_Y5O4C6a...RGFGUllPMFNZZms "
the orbits look to be making 60 degree orbital changes
http://imgbox.com/Y9E6D1QB
what spk files are you using ? ( RORL_DL_??????????? .bsp)
@JohnVV those orbits are from the early mapping phase from the end of last year. You can use the slider below the 3D window to go to the current date.
I am using RORB_DV_????.BSP for rosetta and CORB_DV_????.BSP for 67P. Comet frame of reference comes from CATT_DV_????.BC, though i am not completely sure i applied that 100% correctly.
@chuck0 I agree that you probably don't have the orientation of 67P quite right in your web app right now. I compared ROSETTA NOW!, which I believe has been shown in the past to definitely have the correct orientation for 67P, to the approximate (had to zoom in, so perspective is off) view from Rosetta in your web app for the same minute and it looks like yours may be off by 90 degrees about the rotation axis? Or something like that.
Thanks for that tip. It seems like a 90 degree rotation around the north south axis improved things considerably... now the philae deployment looks pretty consistent with the video pusblished by ESA.
Some really interesting info about the optical navigation they are using around 67P
https://www.youtube.com/watch?v=_3k03Jb3dgQ&feature=youtu.be
http://blogs.esa.int/rosetta/2015/07/14/hello-pluto/
Apologies, but I couldn't resist...
EDIT: and the next day, a more serious release:
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Highlights/Boundary_conditions
Corresponding blog post:
http://blogs.esa.int/rosetta/2015/07/15/getting-to-know-rosettas-comet-boundary-conditions/
Aside from the Pluto image there has been a release of some more OSIRIS images in this blog post about geologic regions
http://blogs.esa.int/rosetta/2015/07/15/getting-to-know-rosettas-comet-boundary-conditions/
Seems like Rosetta will now restart doing full orbits oround 67P.
ROSETTA AND PHILAE STATUS UPDATE : Posted on 20/07/2015
http://blogs.esa.int/rosetta/2015/07/20/rosetta-and-philae-status-update/
Extract:
Some more OSIRIS NAC images available here! Our cup runneth over. Thanks Holger and team, some really nice goodies here.
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Highlights/Inside_Imhotep
This intermittent communication with Philae is concerning.
67P is now spraying out large, dense columns of finely powdered dust, ice crystals and gas. Doing so at considerable velocity. Electrostatic discharges within fine powders are an extremely hazardous phenomenon here on Earth. (Oxygen has a bit to do with that too.). Nothing messes up radio communications like electrostatic discharges. Shifting slightly to the dark side of the terminator might be an option, further from the peak daytime activity, possibly a wise precaution with Perihelion approaching.
Yeah, i think Philae is really going to have a hell of a ride... not only because of the interference which might be generated by the dust but also because the southern hemisphere is supposed to loose up to 20m of material during perihelion ( http://blogs.esa.int/rosetta/2015/02/09/seasonal-forecasts-for-67pc-g/ ). I think it is no wonder that Philae might be moved around quite a bit in the coming weeks. If it still can keep in shadow long enough to stay cool it would be really really nice to see an up to date image from the surface (i think the sequence they are trying to blind command is containing at least a rolis image... wish they could also get a new CIVA pano).
The increasing brightness of the coma should enable a sneak peak at the missing Southern hemisphere. Might be a useful "before and after" exercise.
Given the increasing level of activity on the comet combined with Philae's issues it's not at all surprising that the team is not able to provide updates as frequently as some would like. I'm sure that they're struggling to keep up with rapidly changing circumstances on all fronts.
ADMIN NOTE: About 10 posts above were removed that related to the OSIRIS team policy on image releases. We don't need to go over old ground on this one and it is a clear breach of http://www.unmannedspaceflight.com/index.php?act=boardrules. Thanks all.
@Sherbert yes i am also really looking forward to seeing more pictures of the southern hemisphere. I hope that they will publish some nice navcam images early on. Rosettas trajectory will give it a good view of the south for two weeks starting somewhere around tomorrow. It seems like there is also one last Philae listening pass planned around August 17th. After that they will actually leave the terminator plane and back off quite a bit more behind the comet.
A new block of NAVCAM data was released today.
http://imagearchives.esac.esa.int/index.php?/category/67
ftp://psa.esac.esa.int/pub/mirror/INTERNATIONAL-ROSETTA-MISSION/NAVCAM/RO-C-NAVCAM-2-ESC1-MTP011-V1.0/
And pre-landing data in the archive now! http://blogs.esa.int/rosetta/2015/08/03/first-release-of-rosetta-comet-phase-data-from-four-orbiter-instruments/
actually, for OSIRIS
I would barely call it "approach".
http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2014/06/comet_on_4_june/14582721-1-eng-GB/Comet_on_4_June_node_full_image_2.png
The OSIRIS data release actually also includes the asteroid flybys and the gravity assist swingbys, which i think hadn't been released before (not sure). On the ESA Archive Image Browser, which is a lot more public-user-friendly than PSA.
The copyright notice in the ESA Archive Image Browser for OSIRIS pictures may also be noteworthy:
OSIRIS images of a very short-lived outburst on July 29:
http://www.jpl.nasa.gov/news/news.php?feature=4687
A lot of good stuff in this 2 HOUR hang out from this morning...video with a new outburst caught in the act last night, etc.
ESAHangout: Rosetta mission's day in the Sun
https://www.youtube.com/watch?v=TaBZbc6WGLs
Craig
All of the MIDAS data from the Pre-Landing phase was published to PSA yesterday.
ftp://psa.esac.esa.int/pub/mirror/INTERNATIONAL-ROSETTA-MISSION/MIDAS/RO-D-MIDAS-3-PRL-SAMPLES-V1.0/
Here is a little light reading on "The Joys of Perihelion":
http://blogs.esa.int/rosetta/2015/08/13/rosettas-big-day-in-the-sun/#comment-505564
and these are .PDF papers on various comet processes that might be related to the perihelion passage:
"Heat and Gas Diffusion in Comet Nuclei"
http://www.issibern.ch/PDF-Files/SR-004.pdf
"The outburst triggered by the Deep Impact collision with ..."
http://faculty.cua.edu/ipatov/di-mnras.pdf
"Physical Mechanism Of Comet (and Asteroid ..."
http://www.hou.usra.edu/meetings/metsoc2015/pdf/5002.pdf
"Cavities as a source of outbursts from comets Sergei ..."
http://arxiv.org/pdf/1103.0330
Memorable Comets of the Past
http://cometography.com/past_comets.html
Enjoy.
--Bill
The raw data collected by Rosetta's Ion Composition Analyzer (RPC-ICA) from 2014-03-26 through 2014-11-20 became available in PSA on the 14th.
ftp://psa.esac.esa.int/pub/mirror/INTERNATIONAL-ROSETTA-MISSION/RPCICA/RO-C-RPCICA-2-PRL-RAW-V1.0/
The raw data collected by Rosetta's Ion and Electron Sensor (RPC-IES) from 2014-03-24 through 2014-11-20 became available in PSA on the 7th or 12th. Not sure how I missed this one until now.
ftp://psa.esac.esa.int/pub/mirror/INTERNATIONAL-ROSETTA-MISSION/RPCIES/RO-C-RPCIES-2-PRL-V1.0/
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