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HiRISE and Mars Polar Lander
ugordan
post May 17 2008, 05:24 PM
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How accurate is that, anyway?


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djellison
post May 17 2008, 05:33 PM
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http://www.msss.com/mer_mission/finding_mer/ - and I'm sure it's improved since then. I'm sure it'll be enough to say 'it's in THIS HiRISE image' giving us a realistic chance of identifying the site from local features / rock patterns etc.

Doug
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ugordan
post May 17 2008, 06:52 PM
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That's pretty cool, I didn't know the orbiting spacecraft relays could even measure the Doppler shift. Techniques like this really give the term "nailing it down" meaning.


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jamescanvin
post May 17 2008, 07:58 PM
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This caught my eye, back-shell top-left, parachute bottom-right:

Attached Image


I don't think it can be though as they are separated by 80m, I assume the parachute lines were a lot shorter than this?


James


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djellison
post May 17 2008, 08:05 PM
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Yeah, more like 10m, not 80. That looks like what would happen if someone tried to fake a backshell and chute out of rock smile.gif
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jamescanvin
post May 17 2008, 08:32 PM
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Yeah thought so, the MPL landing ellipse seems to be littered with rock carvings of back-shells, parachutes and landers!

This is going to be hard...


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Reed
post May 17 2008, 08:38 PM
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QUOTE (elakdawalla @ May 16 2008, 01:05 PM) *
One thing I want to do is create my own base map and see where there are areas of overlap between images. One good test for the viability of a candidate is to see how it looks under different lighting geometry, which you can do if you are lucky enough to have found a candidate near the edge of an image where it may have overlapped another.

--Emily

This may help: http://global-data.mars.asu.edu/bin//hiris...=3&cookie=0 although the zoom is pretty limited. If you click a point with the select tool, you get a list of images covering that point. Actually finding the corresponding point on the images will still be a bit of work.

You can also select MOC images on the same site, which probably aren't high enough res to see the lander but might provide useful context.
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djellison
post May 17 2008, 08:42 PM
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QUOTE (Reed @ May 17 2008, 09:38 PM) *
You can also select MOC images on the same site, which probably aren't high enough res to see the lander but might provide useful context.


MOC should, however, resolve the backshell and the parachute. It did with Spirit and Opportunity. When I go MPL hunting - that's what I look for. - If you compare the 'how far it got' elements of EDL, with what you should be able to find on the surface..

DOA / entry failure : Aeroshell impacts at speed, crater, probably unidentifiable.
Failure of chute : probably same as above
Chute deploys, rest a failure : chute and backshell
Lander seperates, but then fails : chute, backshell, heatshield impact site and small probably unidentifiable impact

So in almost any failure mode, the chute and backshell should be visible. What impact the climate would have w.r.t. burying them, covering them etc I don't know, but the Pathfinder chute is clearly visible to HiRISE.

Doug
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centsworth_II
post May 17 2008, 08:50 PM
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QUOTE (jamescanvin @ May 17 2008, 04:32 PM) *
...rock carvings of back-shells, parachutes and landers!

What exactly are you saying? dry.gif
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djellison
post May 17 2008, 09:05 PM
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That nature can play tricks on people. When you're looking for a backshell, all the rocks look like backshells.

Doug
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Guest_Sunspot_*
post May 18 2008, 09:18 AM
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Guests






Having looked at parts of the landing site with HiRISE images, some of it looks treacherous.... I wonder, had the MPL team had images with that resolution available to them when planning the landing, would they have chosen a different area?

Also, illustrations of what MPL would look like from orbit show it with the solar arrays deployed, if it did fail during the entry phase, deployment is unlikely to have happened ? - making it even harder to see.
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ugordan
post May 18 2008, 10:48 AM
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I've now gone through all the images, all of them at half resolution except two ones (on of them being PSP_005536_1030), concentrating on rougher and brighter terrains where it would be easier to miss something. I operated under the assumption that given the jumbled look of some of the terrain with large albedo variations, my best bet would just be looking for a backshell and/or parachute. If the EDL sequnce didn't get as far as parachute deployment, finding the crash site is going to be tough to say the least. If there is a parachute and backshell somewhere, it would be readily apparent even at 50 cm/pix and this speeds up the search significantly. There was (to my eye) not a single candidate for the backshell in any of the images. Given the roughness of some of this terrain, I'd say the lander tipping over at touchdown is a pretty plausible failure scenario as well. I'm left to conclude that it either isn't located in these images (or, by some sick chance, it's in one of the data dropout gaps) or there is no backshell.

How high was MGS coverage of the landing ellipse and at what resolution? MGS later resolved the MER chutes, but that was using cPROTO.


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Guest_Zvezdichko_*
post May 18 2008, 03:26 PM
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Gordan: Check up this: http://mars.jpl.nasa.gov/mgs/msss/camera/i...nder/index.html

The resolution was about 1.5 m per pixel. "Thus, the MOC team is basically trying to distinguish one or two pixels from nearly 150 million. One team member has remarked that this is like "trying to find a specific needle in...a haystack-sized pile of needles."
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tim53
post May 18 2008, 03:32 PM
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QUOTE (ugordan @ May 18 2008, 02:48 AM) *
How high was MGS coverage of the landing ellipse and at what resolution? MGS later resolved the MER chutes, but that was using cPROTO.


ugordon:

Indeed this is a difficult search! The MOC coverage is pretty good over the terrain where MPL was expected to have touched down if all went according to plan. I can't remember the number of images that overlapped at the "candidate object" I talk about above, but it was probably at least 2 or 3. The earliest of these was taken within 2 or 3 weeks of landing, and since it doesn't show anything unusual at that location, I have to believe that the candidate is most likely a frustratingly-lander-looking natural feature. Or (and this isn't very likely), dust accumulation was so fast as to mask the brightness of the parachute that soon after landing. And even in that overly-optimistic scenario, if the lander made it to the ground and deployed its solar panels, why didn't we hear from it? At least briefly?

The MOC coverage of the MPF landing site is particularly interesting in regards to searching for MPL, because imaging the landing site began within a year of the landing. So it's possible to look at changes in the visibility of things like the parachute over time. Because the backshell and parachute weren't visible from the ground, I didn't think the bright splotch at that location taken by MOC (http://www.msss.com/moc_gallery/ab1_m04/images/SP125603.html) was anything unusual (you can't really identify the backshell as obvious "hardware" in any of the MOC images for this reason). But since there are multiple images here, taken over many years, you can see how these objects "fade" with time.

Again, the best chance of finding MPL is if the parachute did in fact deploy, as it's potentially the most expansive piece of spacecraft hardware and ought to be verifiable in MOC images taken shortly after the landing. Since nothing unusual was identified during that search, it seem more likely that the lander crashed, or it landed outside the MOC search images - which would require it to have not landed where it was supposed to. Or the chute did deply, but may not be spread out on the surface, but clumped into a small area.

-Tim.
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climber
post May 18 2008, 03:49 PM
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What about if the chute deployed and failed in pieces like for the MER first envisioned chute?
May be in this configuration, the whole spacecraft slowed down so the crach was not at full speed. A failed parachute (in piece) may have never been visible to MGS and now to HiRise. So, if the spacecraft is still in the back+heat shield, are they both white? Is there any chance that the colour was not bright enought and the landing not hard enough both to be visible by MGS?


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