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HiRISE and Mars Polar Lander
tharrison
post Jan 10 2010, 10:48 PM
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If you want to expand your search beyond the MPL landing ellipse, you might try looking at CTX images as well, as the Phoenix hardware is all visible in CTX.


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Guest_Sunspot_*
post Jan 11 2010, 01:32 PM
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Has the entire landing ellipse been covered by HiRISE now? If the hardware were as obvious on the surface as those of phoenix/MER etc, I would have thought something would have been seen by now. Im wondering if we will ever find it now. Or perhaps something else went wrong in the early decent and it was destroyed in the atmosphere.
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Phil Stooke
post Jan 11 2010, 04:34 PM
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The last comment I saw from Tim Parker was that a small spot in a CTX image outside the HiRISE coverage would be looked at in HiRISE as the season became favorable again.

Phil


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tharrison
post Jan 12 2010, 02:51 AM
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QUOTE (Sunspot @ Jan 11 2010, 05:32 AM) *
Has the entire landing ellipse been covered by HiRISE now? If the hardware were as obvious on the surface as those of phoenix/MER etc, I would have thought something would have been seen by now. Im wondering if we will ever find it now. Or perhaps something else went wrong in the early decent and it was destroyed in the atmosphere.


Yes, it has, and CTX acquired continuous coverage of a good area outside of the ellipse as well. As one of the CTX science operations team members, I can tell you that we've looked at all of the CTX and MOC images in and around the ellipse and haven't found anything particularly promising. I'll be interested to see what the spot is that Tim Parker is referring to.


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elakdawalla
post Jan 12 2010, 03:08 AM
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Tanya, let me be the first to welcome you to unmannedspaceflight.com! I'm sure I can speak for all the members when I say I'm looking forward to your perspective on stuff in space! CTX doesn't get nearly enough love -- just by posting here you'll help to get it a little more attention.

[But ewww, a Wesleyan grad. Go Ephs.]


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mcaplinger
post Jan 12 2010, 06:34 AM
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QUOTE (Sunspot @ Jan 11 2010, 05:32 AM) *
Has the entire landing ellipse been covered by HiRISE now?

I think that may depend on your definition of "entire landing ellipse"; there were several based on various assumptions of atmospheric conditions and entry state, some larger than others. See http://www.msss.com/mars_images/moc/1_24_0...nder/index.html though I am not sure what current thinking about this is.


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tharrison
post Jan 13 2010, 01:36 AM
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QUOTE (elakdawalla @ Jan 11 2010, 07:08 PM) *
Tanya, let me be the first to welcome you to unmannedspaceflight.com! I'm sure I can speak for all the members when I say I'm looking forward to your perspective on stuff in space! CTX doesn't get nearly enough love -- just by posting here you'll help to get it a little more attention.

[But ewww, a Wesleyan grad. Go Ephs.]


Thanks! smile.gif CTX is definitely under-appreciated by both the public and the scientific community. It is an AMAZING dataset, and the images are simply stunning. Part of my job is to look at every image that comes back from CTX each day, and I never get tired of it.

Here is a CTX image (P22_009725_2484_XI_68N125W) of Phoenix from back in August 2008; admittedly, this doesn't showcase the CTX at its best as the image is a bit murky, but that's hard to avoid at the Phoenix landing site:



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elakdawalla
post Jan 13 2010, 03:03 AM
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That's cool, it certainly stands out! -- and an advantage of lower resolution is that the image doesn't look as cruddy as the HiRISE images from the same time period smile.gif

To get to the full CTX frame knowing any image number, append "http://viewer.mars.asu.edu/planetview/inst/ctx/" to the front, so this one is

http://viewer.mars.asu.edu/planetview/inst...2484_XI_68N125W


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algorimancer
post Nov 10 2011, 06:48 PM
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I was just reading this article on the difficulties of finding/identifying non-human artifacts around the solar system (http://news.discovery.com/space/our-solar-system-might-be-littered-with-alien-artifacts-111109.html), which included this picture of the 14 ft wide Lunar Surveyor 6 lander, as seen by the LRO:

http://blogs.discovery.com/.a/6a00d8341bf6...15b68970d-800wi

The low sun angle really makes this lander stand-out clearly as a spike of shadow. Certainly it could be confused with a boulder, but at least in this case there're not a lot of boulders around to confuse the issue. This leads me to wonder whether the search for the Mars Polar Lander might be revisited using low sun angle images from MRO. Or was this an aspect of the existing search?


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djellison
post Nov 10 2011, 07:11 PM
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Given the latitude of the MPL landing site - the sun is always at a low angle.
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algorimancer
post Nov 10 2011, 08:01 PM
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QUOTE (djellison @ Nov 10 2011, 01:11 PM) *
...the sun is always at a low angle.

I estimate that it could range from about 0 to 50 degrees depending on season and time of day. I would consider low sun angle to be less than approximately 15 degrees to yield a real benefit in feature recognition. If the terrain is as flat as what Phoenix observed, MPL should leave a very prominent spike of shadow at such a low sun angle. Obviously this would be less-so in rocky or high-relief terrain. Scattering from dust in the atmosphere would weaken the contrast of the shadow at all sun angles, so images during times when there is little dust in the atmosphere would be optimal.
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djellison
post Nov 10 2011, 10:01 PM
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QUOTE (algorimancer @ Nov 10 2011, 12:01 PM) *
I would consider low sun angle to be less than approximately 15 degrees to yield a real benefit in feature recognition.


When the SNR will be poor because it's so dark.


QUOTE
If the terrain is as flat as what Phoenix observed,


It isn't.

QUOTE
MPL should leave a very prominent spike of shadow at such a low sun angle.


After a decade of seasonal frost crushing?

If you didn't know where PHX was....could you find it in the pictures taken a martian year after landing? Now make that 5x worse. I doubt it'd be visible at all.




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algorimancer
post Nov 11 2011, 02:33 AM
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QUOTE (djellison @ Nov 10 2011, 04:01 PM) *
When the SNR will be poor because it's so dark.

Clearly there would be some optimal balance between solar angle and optimal shadow SNR, as a function of atmospheric dust load. It seemed to work rather well on the low albedo lunar surface, I'm not sure how that compares with the lower insolation on the higher albedo Mars in combination with scattering from atmospheric dust.

QUOTE (djellison @ Nov 10 2011, 04:01 PM) *
It isn't.

Clearly there is a blend of topography, some regions rather flat, others less so.

QUOTE (djellison @ Nov 10 2011, 04:01 PM) *
After a decade of seasonal frost crushing?

Good question. I don't know. Possibly this completely invalidates the notion. Has it been modeled?

QUOTE (djellison @ Nov 10 2011, 04:01 PM) *
could you find it in the pictures taken a martian year after landing?

Definitely more challenging considering the additional dust cover and crushing. On the other hand, the combination of a suggestive spike of shadow from a recent low solar incidence angle image, with a clearer image from the original search campaign, might be sufficient to firm-up an identification.

I don't have all the answers. It may or may not be worth doing, which I why I put it out there for (ideally, constructive) discussion.

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