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HiRISE and Mars Polar Lander
MarsIsImportant
post May 13 2008, 09:52 PM
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QUOTE (ugordan @ May 13 2008, 03:28 PM) *
Someone over at the Bad Astronomy site has shown that same area, which image is that? I haven't ran across a feature like that. It looks like a hill to me, do you know what direction the illumination is from?

Doug, if only we could be 100% positive there was a chute deployed. For all we know, the lander could have blown up the minute after last contact prior to entry and we'd still only have the most likely cause to assume (40 meter high crash).


I found this on my own. The suggestion of 'bad astronomy' was not a very nice comment.

This is an image from HRISE and closer to the center of the landing ellipse. I believe Mars time is about 2:30 PM.

It looks like a possible parachute. I thought of a hill but the folds suggest otherwise. I may have found the parachute draped over a rock of some sort. Regardless, the feature is very strange and does not appear to be natural in origin, especially given the surrounding terrain.

I've just noticed some other nearby targets--just a little further away (they don't look like this, but who knows what I will find). I'm going to get a closer look at them. They are much smaller in size.

Meanwhile I have other things to do. I will get back with you later.
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tim53
post May 13 2008, 10:04 PM
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QUOTE (elakdawalla @ May 13 2008, 01:05 PM) *
Just to be clear, is your "candidate" the lander, an impact site, or the parachute? I'm preparing a Web page with info for the search and I was going to tell people that the parachute/backshell was the best object to be searching for, with examples of what they look like at the successful landing sites -- should I also try to give examples of what the lander/crash site should look like? If so I'll need some help from image magicians here to come up with sample images.

--Emily


MPL searchers beware: Potential spoilers to follow!


The image my gizmoid is in is PSP_005536_1030. The objects look similar to a "lander" and "backshell", but they're too big. The putative backshell object is about 5 meters across, whereas the actual backshell is just over half that size. So, if it's real hardware, it's sitting on a rise that's similar in brightness and shape, so that it resembles a single conical object 5 meters across at the base - not impossible, but reducing the chances (and definitely the certainty) that it's hardware. The putative lander object does not match the shading I get when I illuminate a lander model with the same lighting geometry as the HiRISE image, though I initially thought it did, when I compared it to a simulated image produced by MSSS during the search with MOC. Still, not impossible for it to be a lander, particularly if it's tilted or oriented or mangled in a manner that's hard to anticipate. But the poor match to the model does reduce the possibility that it's hardware and not a natural object.

When I first saw these objects last fall, I got pretty excited by their apparent similarities to other lander hardware we've seen in HiRISE images and the fact that they're within a few kilometers of the center of the Nav ellipse. But in addition to the scales and lighting issues, there is no bright patch near the putative backshell that might be a parachute. So, I wondered if it might be dust mantled after all this time. And so I've searched corresponding MOC image coverage (specifically M1104140, taken less than 2 months after the loss of MPL), and there aren't any anomalously bright OR dark spots at the locations of these features. The color coverage by HiRISE does run over these features but, unlike the other hardware we've seen in color, neither of these objects appears blue-tinted in color - they match the surrounding surface color.

So, if this is the lander, it was more or less "successful" at reaching the surface intact, it's oriented wrong by about 45 degrees or so, possibly tilted, and it was mantled so as to not stand out from its surroundings rather quickly after the landing... ...in other words, it's not bloody likely to be the lander.

Early on in my search, I identified a dark spot in a CTX image to the south (and thus downrange) of the center of the nav ellipse, and a few hundred meters beyond the HiRISE coverage. It'll be interesting to see this spot in HiRISE come spring, in the off chance it's an impact site. There is no MOC coverage of this feature (at least not of sufficient resolution, IIRC), as it was just outside the search area for MPL. But except that this is an isolated dark spot in that image (beyond a field of dark splotches in that area), there's nothing particularly remarkable about it, and it might just be a site of defrosting or a dark dust streak, and thus a natural feature.

-Tim.
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ugordan
post May 13 2008, 10:05 PM
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QUOTE (MarsIsImportant @ May 13 2008, 11:52 PM) *
I found this on my own. The suggestion of 'bad astronomy' was not a very nice comment.

There's nothing wrong with Phil Plait's Bad Astronomy site. I didn't allude you stole that image, I just wanted to say I saw that feature posted earlier and wanted to know which image it apears in. I didn't come across it in the several images I looked at and it does look hard to miss. Without knowing context, that still looks to me like topography


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tim53
post May 13 2008, 10:07 PM
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QUOTE (MarsIsImportant @ May 13 2008, 01:17 PM) *
I finally have a real close-up view of my feature. It is strange. I'm not so sure it is the lander, unless the parachute landed on top of it and is completely draped over it.

Here is a view.

[attachment=14207:Search_f...Feature1.jpeg]

There is nothing like this anywhere near. Most other features nearby are dark colored sand dunes.


That's a conical pit. There is another one in the region. I remember wondering whether this might be the lander, sunk into the ice. But it's a pretty big hole. I think I measured it around 50 meters across. I think other similar pits can be found elsewhere in this terrain, though I don't think there were any near this one.

-Tim.
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elakdawalla
post May 13 2008, 10:45 PM
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Anybody else suddenly having problems with the HiRISE website?

--Emily


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MarsIsImportant
post May 13 2008, 10:48 PM
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Here context for the feature I showed.


Attached Image


(I had another image in mind but it is too large of a file.)



There is a lot of dust in the area. A bright parachute would be mostly covered in that dust.

The source file is PSP_005114_1035_RED.NOMAP.JP2

The feature cannot be a conical pit because the lighting is all wrong for that at this time of day. At 2:30, the sun light is coming from the top left corner of the image. A hill is more believable; but the radiating folds suggest something more complex. The hills in the area are relatively smooth with dark sand dunes on top.
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ugordan
post May 13 2008, 10:50 PM
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QUOTE (elakdawalla @ May 14 2008, 12:45 AM) *
Anybody else suddenly having problems with the HiRISE website?

It stopped working for me about half an hour ago. What's worse is IASViewer won't even start up due to this...


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tim53
post May 13 2008, 11:06 PM
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QUOTE (MarsIsImportant @ May 13 2008, 02:48 PM) *
Here context for the feature I showed.


Attached Image


(I had another image in mind but it is too large of a file.)



There is a lot of dust in the area. A bright parachute would be mostly covered in that dust.

The source file is PSP_005114_1035_RED.NOMAP.JP2

The feature cannot be a conical pit because the lighting is all wrong for that at this time of day. At 2:30, the sun light is coming from the top left corner of the image. A hill is more believable; but the radiating folds suggest something more complex. The hills in the area are relatively smooth with dark sand dunes on top.


Acually, the sunlight is from the lower right. The sample you show is of one of the "spider" features first identified by MOC. These are sinuous radial troughs that are deeper near the center of the "spiders" and shallowing outward where they branch and disappear. In stereo, these are similar to dilation cracks in frost heave structres in the arctic, "pingos". But pingos typially have much lower base:height ratios than the "spiders" do.

-Tim.
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elakdawalla
post May 13 2008, 11:10 PM
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Yay, the website seems to be back up.

--Emily


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MarsIsImportant
post May 13 2008, 11:18 PM
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Sorry, but the illumination is not from lower right. It is from the upper left. That I am absolutely sure of.
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tim53
post May 13 2008, 11:38 PM
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QUOTE (MarsIsImportant @ May 13 2008, 03:18 PM) *
Sorry, but the illumination is not from lower right. It is from the upper left. That I am absolutely sure of.


Check the label.


North azimuth is listed as 95 for the NOMAP version of that image. The north azimuth is measured clockwise from the right side of the frame (0). Subsolar azimuth is listed as 50.6, so sun illumination is from the bottom right of the scene.

Again, the feature you show in the cropped area is a depression, not a high.

-Tim.
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elakdawalla
post May 14 2008, 04:36 AM
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MarsIsImportant, I was also completely confused about what the north azimuth meant for HiRISE images until I had a conversation with some of the HiRISE folks. As Tim says, the north azimuth for the non-map-projected images (which are the ones I would recommend for performing these searches, as they represent non-resampled data) are measured clockwise from the right side of the frame (which I find counterintuitive enough; it gets worse). For map-projected images, it's the same, as long as you're dealing with an image that is not close to one of the poles. Polar images are in a polar stereographic projection, in which lines of latitude make concentric circles around the pole, and lines of longitude are straight, intersecting at the pole. So in the map-projected images of places close to the pole, north is not necessarily up. Which direction north is depends upon what longitude you're looking at. If you're looking at a place near longitude 0, north will be up. However, the Mars Polar Lander landing site is at 165, which is to say very close to longitude 180, so the map-projected images have north almost straight down. For the one you are looking at, PSP_005114_1035, the direction to north is given as 75 degrees, which (when you measure it clockwise from the right side of the frame) gives you a north direction that is only 15 degrees to the right of straight down.

I think Tim Parker would be the first to admit that he is not always right. But I think that if Tim says he's sure about something, you should consider it to be pretty likely that he's right. smile.gif

--Emily


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MarsEngineer
post May 14 2008, 05:05 AM
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Hi friends (and Hi Tim ... we have to stop meeting like this),

My thoughts are:

1) We really do not know what caused MPL to disappear. While the MPL failure review board identified the "most probable cause" as a premature shutdown of the descent engines at about 40 m above the ground due to a software bug, that bug was only one of several possible failure modes that were identified then and since. We can not make too many assumptions as to what the lander looks like. (But I do think it is there somewhere.)

2) Unless Mars itself camouflages the vehicle (e.g. by overlaying layers of dust in the annual CO2 ice deposit, or the lander has fallen into one of the larger "spiders"), I think we should see something. The lander's design (including heat shield and backshell) used a lot of highly reflective MLI (multi-layer insulation) blanketing in many key places. I suspect that regardless of how it landed, there should be pieces of highly reflective material that are exposed and would result in one or more "hot pixels". Check out the image of the airbag cover from 1997 Mars Pathfinder's landing on slide 6 or 7 as well as the Mars Pathfinder heat shield debris here http://hirise.lpl.arizona.edu/HiBlog/wp-co...HiRISE_talk.pdf.

Note how bright that 1 meter round piece of airbag cover MLI is. We saw it in the distance in 1997 but it was only after we got the view from HiRISE that we realized that it was airbag cover debris.

3) We have not yet covered the landing ellipse with HiRISE images. I think we have covered more than 50% but there is still room to believe that MPL landed outside the areas imaged so far. The HiRISE/MRO team stopped imaging the MPL area once the southern summer sun set. As Tim suggests, the lander could be a km from one of the edges of any of these images.

I am betting on next year! While our eyes are sore (especially Tim's) and our image processing software did not yield anything, we could be wrong ... these images cover a lot of territory. Please let the HiRISE gang know if you find something! Our inquiring minds want to know!

Take care!

-Rob Manning

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These comments are solely those of the author and do not reflect the views of JPL, Caltech nor NASA.
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MarsIsImportant
post May 14 2008, 05:23 AM
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Emily,

The azimuth on the label Tim pointed out for the non-map image that I posted is 95 degrees. It points north relative to the map. That is basically a right angle that points North. That clearly points to the right of the image. West is toward the top of the image. East is on the bottom of the image. The South Pole is toward the left of the image as you face it.

I am correct. I have no doubt.
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MarsIsImportant
post May 14 2008, 06:23 AM
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I've been taking a look around that same JP2 image. Many spiders appear to be depressions and cracks. Others are dunes.

Also the lighting appears to change in different parts of the image. Perhaps this is because it is so close to the South Pole. Perhaps the azimuth is only good for the center of the image. Or the label is wrong, which would have led me astray in my conclusions. Some parts of the image appear to be lighted from the bottom right. Or it maybe just too late at night and my eyes are playing tricks.
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