Oh for sure.

It's the right-most object's extended distance from the lander and the lack of conclusive shadows from the left and right bright spots that concern me.

Click to view attachment

I did a 50% Equalize to the lightness component of these images. The Lander now appears very dark and where it would cast shadows there are two white patches (especially noticeable in the rightmost (later) image). I've been looking at a lot of snow this winter and this image looks like frozen precipitation not melting as rapidly in the shadows of the solar panels.

Steve M

But remember the sun is moving around the sky such that the solar array's shadows will not stay in one spot. I would not expect their shading to provide ample protection to any patch of ground.

Edit:

Especially if the lander body itself doesn't do this!

As the sun gets higher with the seasons' progression, will we get better pictures ?

Third and final communication attempt to begin on April 5th.

Now I'm not sure about the credibility of this source, but according to this article they might be considering a fourth communication attempt in May around the solstice. (Assuming the one next week fails.)

Ken's a UMSF member in good standing who frequently reports on these topics. He's a bit of a loon about Mars but I'd say he's credible.

In case you guys haven't heard, there was no signal from Phoenix during the 3rd listening period. They are going to evaluate if further attempts should be tried. (Probably around the solstice, if at all.)

http://marsprogram.jpl.nasa.gov/news/whats...&NewsID=992

Like many, I'm not so sad because I was not expecting any signal back from Phoenix...
The poor thing surely died during the winter
My only interest is to see whether or not the solar panels have snapped off (or were bent) to the ground under the winter heavy ice load
I'm now waiting to see the next HiRise images...

Suppose just one solar panel snapped off, but the other was still functional. In that case, it might take the greater solar illumination near the solstice to revive the craft.

Suppose regional dust storms deposited material on the snow and ice as it was rising and then subsiding (when the ground was patchy). As the ice sublimated it would leave one or more layers of concentrated gunk the way retreating glaciers and snowbanks do on Earth. Therefore a cleaning event sometime down the road might raise power levels sufficiently, hopefully not after the final communication attempt.

I haven't seen this done yet. So I went ahead and did it.

Anyone ever notice that Phoenix moved over?

You can see how the ground was disturbed by Phoenix landing, and now that it's moved over, that spot on the surface is now visible to MRO.

In fact, I'm really starting to think that Phoenix tipped over. The bright part is the deck facing the sun, the darker part is perhaps the underbelly in the shade behind the deck. Would be interesting to see this with the opposite illumination angle.

(animation)

I think you have something there; that looks like too much to be caused by lighting changes alone.

Based on the position of the legs, there's only three ways that Phoenix can tip over if it were to do so, and the direction we observe it to move is one of them.

I'm at a loss as to what would be the mechanism for this though.

The CO2 ice loading scenarios for mid winter were pretty severe - I pulled some numbers in a post quite some time back ( here ) where I was guessing that there could be up to 25cm of CO2 ice on the deck\panels at the most extreme point. If that was just fluffy frost then it could be survivable but if that was more or less solid CO2 ice then that would be about 2.5 tons of ice - that could explain a toppled rover\solar panels stripped off.

Wouldn't it collect more or less evenly on the deck?

I suspect you are right that the ice would collect evenly.

But when the sun returned in the spring, perhaps the low sun angle would allow for one or two of the panels to be shaded more. If sublimation is quicker on some panels than on others, then the load of ice might perhaps be enough to shift the center of gravity enough to cause the lander to topple.

David

Sort of like when icebergs here on Earth tumble around as they melt. They get top heavy and eventually flip right over.
Except of course with dry ice instead of water!

Well, I suppose Phoenix has managed to overcome its lack of a traditional mobility system...

I'm just curious as to know if the Phoenix flight DVD or a model was load tested before launch? Considering how much C02 ice was probably on the deck, as well as the DVD it self, plus if Phoenix actually did tip over, that little disc sure has been through allot of torcher.

As far as I can see from the animation, the lander's shadow hasn't moved very much at all. Depending on the lighting geometry, Phoenix is still there on the spot, just camouflaged by the ice, dust and TEGA samples.

I've placed an outline of the lander from the first image on the second, matching a couple of points as best I could.
The most obvious question is, what happens to the shadow from the right solar panel?
Click to view attachment

I see what you mean. Would be nice to get a pic with a lower Sun angle, but IIRC MRO's in a Sun-sync orbit, right?

The difficulty thus far finding MPL is becoming less & less mysterious, it seems.

I thought the sun was low in these spring images. We had to wait until it rose above the horizon at all before the image campaign began.

Thanks to you nice image processings, Hungry4info and centsworth_II , there are now several options that can be discussed to better understand the current state of the Phoenix s/c :

1. the dark color of the s/c itself : even though there is a low sunlight, it is no longer coloured white or gray (body) and blue or dark blue (solar panels) :
(i) Is it covered now by dirt left by a mix of ice and dust and... what else ?
(ii) Has the s/c completely collapsed under the heavy ice load (2.6 tons...) and was almost flattened to the ground ? (meaning a quasi "flat" shadow) ;
(iii) is the body intact with only bent or collapsed parts : leg(s), solar panels... ? Then, there is a difficulty to differentiate between the colors created by the shadows and the colors showing real parts of the s/c itself...

2. the shift (move) of the center of the s/c :
(i) has it moved when the ice buit up or sublimated (s/c pushed aside) or just "slided" on it ?
(ii) has it tipped over ?
(iii) is it tilted on one side ?

=> I'm now really waiting to see the next HiRise images with an higher Sun...

It wasn't load tested. The major tests it has undergone include thermal vacuum testing (where it's placed in a vacuum chamber and then run through temperature extremes, mostly to ensure it wouldn't either break due to thermal stress or outgas anything that would impact any of the science) and shock/vibration testing (simulating the rigors of launch and landing). The Phoenix DVD is a much simpler animal than the MER DVD; it has no fancy assembly attaching it to the lander. It is merely a silica glass DVD that is attached to the deck with adhesive and Velcro. My instinct tells me it should be fine under a load, but I don't know. Tipping over Phoenix (if that has happened) should have had no effect at all on it.

Ouf ! Dear "Bloguette par excellence" (it's a great name in French) : I think my name as PSoc member was on it... I might have survived (like other PSoc members) the harsh of the Martian winter after all !

I've been pondering this possibility as well. From my perspective I don't see any "missing" shapes in Centsworth's comparison above (thank you for that).

Another thing about the "weight" of the CO(2) on the panels. That would only be a problem if the ice falls like snow from above. If the CO(2) forms directly from the air like frost, then we'd have an even deposition of ice forming both on top of and under the panels. In that case the panels wouldn't be subjected to "weight" any more than a metal table dropped to the bottom of the ocean would collapse from the weight of the water above.

While the DVD itself might look physically intact, I wouldn't really expect it to be readable after the low temperature extremes it went through. So I wouldn't bet any of "us" survived either.

Unlike normal DVD's, this one was actually a glass disc that is more analogous to being a master from which normal DVD's get stamped than a typical DVD-R or off the shelf movie DVD. It's a fairly robust thing.

I can't imagine any sort of "micro-glacial" action (making up terms here) would cause the observed change in position of the lander without destroying that disturbed patch of ground that was created when Phoenix landed. The ground seems fairly unaltered.

So...

Ice accumulates everywhere on the lander, sun comes up and is low and only in one part of the sky, so only the ice on one side of the lander evaporates, the centre of gravity shifts over, and Phoenix topples over? Maybe throw in a bit of wind that must have occurred to alter the observed shape of the parachute.

For the lander to topple over, either the center of gravity of the load would need to be beyond the area of the legs, or one or more of the legs would have had to fail. How strong were the legs?

The center of gravity of the load might be beyond the area of the legs if a wind-driven sublimation process left an overhang. I think the solar panels extended beyond the legs, so a load there might tip the craft if the panels did not snap off first, but it does not look like it tipped in that direction.

To me, Centsworth's image doesn't suggest that Phoenix tipped, but it does look like the right solar array isn't where it used to be. Could it have drooped due to frost accumulation and/or cryothermal effects?

For the dropping scenario, assuming the lander is upright and the solar array attached, I would assume that the solar array would protrude from the lander less than it does in the post-landing MRO image. We observe the array as being farther from the lander in the post-winter image than it was in the post-landing image, but still in roughly the same relative orientation. Maybe it got dragged along, even if it is on the ground.

Another thing that just hit me is that we can clearly see the shadow of Phoenix in the latest post-winter image. There is no solar array in the way to block our view of that shadow as there is in the post-landing image. I interpret this as the array resting on the surface.

· Lack of observed shadows from the solar arrays (for any illumination angle with which we can see the lander's shadow, the arrays shadow should be visible)
· An apparent increase in the array-lander separation between the post-landing and post-winter images.
· A well observed lander shadow, without the array blocking a portion of it that we would expect to see if the arrays were still at the same altitude as the deck.

If anyone can think of a way that the arrays can be attached despite these lines of evidence, I am all ears.

Hmm, hot topic. I looked at this a bit ago and agree with much above (except tip/shift of the lander), but maybe can add a bit. I think I placed the lander model just slightly sunward compared to the image above. Zoomed out enough, it looks like you can make out some edges, but the lander is dust colored now. FWIW, a better image is needed before even I would believe my conclusions.

I used a model with model shadows for the timing. From that I'd say the one negative is the apparent shadow and the model still seem to overlap some. I'd want a better image to really conclude a negative from that (same with the positives). The most perplexing thing is that the shadow really doesn't look like the lander body shadow; it matches with the body shadow plus the east SA shadow. The west SA shadow is missing, but the model says only a sliver of it should be visible.

An earlier image had me 50% convinced the west SA had collapsed, but I haven't seen anything to confirm or deny that.

If the east array shadow is present, we got some 'splainin' to do. The collapse prediction does not rely on any assumption that CO2 deposition is like snowfall. Frost would form on the coldest surfaces. Surfaces are primarily cooled radiatively, with some reservoir of heat depending on the volume being cooled (among other things). The top of the SA radiates to space or at least the upper atmosphere. The soil under the array radiates to the array. The array has little heat reservoir, the soil has more. The array is the cold finger. Frost accumulates on its top. Maybe on the bottom. But not on the surface underneath, until the array is encased in frost. If the SA survived, it is not due to frost building up to its level from the surface. Some mechanism (wind-related? seems unlikely) kept it defrosted. My impression is that if you built up the frost 1 monolayer of molecules at a time, uniformly, the arrays could hold a lot--but not the back-of-envelope expected amounts. The tolerance for non-uniformity is low. Use one as a table to hold a glass of wine and you have a mess (hmm, does that give away too much about the location where conversations like this take place?). And while one can imagine uniform deposition, one certainly doesn't get that impression from the images.

Thanks Mark for the informed input on both topics.

One point that hasn't been mentioned is that even if you register the ground around Phoenix perfectly between the "before" and "after" frames, then Phoenix itself won't be registered if the viewing angle is different between the two images. That's because the top of the body and arrays is something like a metre above the ground. If there's a difference in viewing angle of order 30 degrees that would produce a significant shift in deck and arrays. This might explain why it looks like Phoenix shifted/collapsed. This could be corrected for given those viewing angles.

In terms of the shadows, it's possible that topography or albedo are confusing the issue.

My impression is that both arrays are still up, and just coated in dust so they match the appearance of the ground. If one had tipped, the illumination angle on that array would be very different from the ground and it should look considerably brighter or dimmer than the ground.

I'm also curious whether the small frosty patches just north of Phoenix could coincide with the major digs, like Dodo/Goldilocks or Snow White? Could the ice exposed in those digs encourage frost/ice around them? My guess is the visible patches are too far from the body, but I haven't done any measurements.

Good point. Now, if someone could identify the IDs of those two images the information about the "viewing angle" can be easily found on their respective webpages.

What kind of difference in angle would be required to make an apparent shift of more than the diameter of the lander?

To me it looks like the shift is only roughly half a solar array diameter. That would be easy to achieve.

The patches seem to be about where the lander + 2 arrays shadow would have been in mid-afternoon 1-2 months before the picture. They don't line up with the digs, and seem to far away.

I'm pretty confused as to what I'm looking at. Still, it seems quite an accomplishment of circumstances to eliminate any trace of a shadow from the array on the right side. What if it is not tipped, but laying flat on the surface?

I also think those are patches of ice that were in Phoenix's shadow.
After I first thought they were reflections of a Phoenix blown to smithereens!

Final Attempts to Hear from Mars Phoenix form 17 to 21 May