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Phoenix - spring images, HiRISE views of Phoenix after the long, long winter
fredk
post Apr 18 2010, 02:44 PM
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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.
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Tesheiner
post Apr 18 2010, 04:18 PM
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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.
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Hungry4info
post Apr 18 2010, 04:30 PM
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What kind of difference in angle would be required to make an apparent shift of more than the diameter of the lander?


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fredk
post Apr 18 2010, 04:42 PM
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To me it looks like the shift is only roughly half a solar array diameter. That would be easy to achieve.
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Deimos
post Apr 18 2010, 08:24 PM
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QUOTE (fredk @ Apr 18 2010, 02:44 PM) *
I'm also curious whether the small frosty patches just north of Phoenix could coincide with the major digs...

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.
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centsworth_II
post Apr 19 2010, 07:41 AM
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QUOTE (fredk @ Apr 18 2010, 10:44 AM) *
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 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?
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centsworth_II
post Apr 19 2010, 07:44 AM
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QUOTE (Deimos @ Apr 18 2010, 04:24 PM) *
The patches seem to be about where the lander + 2 arrays shadow would have been...
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! laugh.gif
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Paolo
post May 14 2010, 08:00 AM
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Final Attempts to Hear from Mars Phoenix form 17 to 21 May


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

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