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Unmanned Spaceflight.com _ Phoenix _ Phoenix - spring images

Posted by: Phil Stooke Oct 26 2009, 02:14 PM

Doug just said in another thread that he was looking for Phoenix in the new images and couldn't find it. Well, I love a challenge. So here it is:

Close-up:

(REMOVED - SEE LATER POST)

Context:

(REMOVED - SEE LATER POST)

Note that map-projected HiRISE images at this latitude are in polar stereographic projection, not a cylindrical projection. North is at the left.

You might not believe this, but by blinking layers like Clyde Tombaugh I think I can match numerous points, not just the hardware.

EDIT: I was a bit off. Correct locations are shown below.

Phil

Posted by: djellison Oct 26 2009, 03:30 PM

I had a go blinking layers, but didn't have any luck - good job on that one. It'll be interesting to see if there were any more pre-safe-mode images. Otherwise we might be in for a bit of a wait for new ones.

Posted by: Sunspot Oct 26 2009, 03:36 PM

WOW those images are so grainy. blink.gif

Posted by: Phil Stooke Oct 26 2009, 04:38 PM

Yes, low light levels and hazy atmosphere made them very low contrast except for ice patches. Later images will be a lot better.

Phil

Posted by: ilbasso Oct 26 2009, 05:03 PM

Looks good to me. I can see some of the same crack patterns in both photos.

Posted by: centsworth_II Oct 26 2009, 05:32 PM

If a meter or two of frozen CO2 formed, I'm surprised that it would have disappeared already.

Posted by: Phil Stooke Oct 26 2009, 06:10 PM

(Sorry Doug - I just noticed this thread should have gone in the Phoenix section... move it if you like)

Phil

Posted by: elakdawalla Oct 26 2009, 06:14 PM

I moved it. Well spotted, Phil! I wondered when somebody was going to give that challenge a try. I'll admit I gave up pretty quickly smile.gif

--Emily

Posted by: Phil Stooke Oct 28 2009, 12:41 AM

Well spotted indeed! Good job indeed! Turns out I was wrong! After a more careful look I discovered the correct location nearby. To avoid duplication I'm posting the new images here, and I'm going to edit out the other images. When the two sides of this comparison are blinked a thousand features match up, not just a dozen. This is a lesson to people searching for Mars Polar lander - it's easy to be fooled! I was in too much of a hurry last time... The parachute and backshell are invisible, the heatshield almost so, but the lander's clear.

Phil

Context:



comparison:


Close-up of the lander:

Posted by: Phil Stooke Oct 28 2009, 12:48 AM

Incidentally, I think, from the blinking approach, that the new images are not at all grainy (as suggested above) - the grain is in the landscape.

Phil

Posted by: elakdawalla Oct 28 2009, 12:54 AM

Thanks for the correction. I was desperately trying to get those images to line up and on the point of banging my head against my newly repaired computer monitor.

Now I have to go see if I can get this version to line up wink.gif

QUOTE (Phil Stooke @ Oct 27 2009, 05:41 PM) *
Close-up of the lander:

If I squint and do a couple of incantations, I think I can see the solar panels. Would it make sense for them to be bright against darker ground? Would they be frostier or dustier or something?

Posted by: ElkGroveDan Oct 28 2009, 02:38 AM

What caused you to go back and reevaluate the location Phil?

Posted by: Phil Stooke Oct 28 2009, 02:44 AM

Emily!

Phil

Posted by: Hungry4info Oct 28 2009, 11:54 AM

If the slightly darker region in the snow to the bottom-left of the lander is Phoenix's shadow, then I can't see any evidence of solar panels in that shadow.

Maybe Emily is indeed seeing the solar panels (I can sort of make them out), but they may not be attached to Phoenix anymore.

Posted by: djellison Oct 28 2009, 12:34 PM

Via HiRISE on Twitter (always superbly informative, fun, and quick) that image was the last before the extended safe mode we're still in with MRO. So it'll be some time before we get a better 'springier' picture sadly.

Posted by: Phil Stooke Oct 28 2009, 07:36 PM

Emily made a really nice animation - well, I should say blinking comparison, maybe - anyway a very nice comparison image of the site, on her blog. Thanks Emily!

Phil

Posted by: centsworth_II Oct 30 2009, 02:22 AM

QUOTE (Hungry4info @ Oct 28 2009, 06:54 AM) *
If the slightly darker region in the snow to the bottom-left of the lander is Phoenix's shadow, then I can't see any evidence of solar panels in that shadow.

The level of CO2 'snow' may be up to the panels in which case they would not cast shadows even if still attached. Any shadow may be from structures on the deck higher than the panels.

Posted by: Hungry4info Oct 30 2009, 06:58 AM

Interesting idea, though with only patchy snow covering, I wouldn't expect that the snow would be very high.

Posted by: centsworth_II Oct 30 2009, 04:23 PM

QUOTE (Hungry4info @ Oct 30 2009, 01:58 AM) *
Interesting idea, though with only patchy snow covering, I wouldn't expect that the snow would be very high.

It looks like Phoenix is sitting in the middle of a patch. Maybe a drift?

Posted by: sgendreau Oct 30 2009, 05:15 PM

QUOTE (centsworth_II @ Oct 30 2009, 09:23 AM) *
It looks like Phoenix is sitting in the middle of a patch. Maybe a drift?


Maybe the drift is accumulating against Phoenix, and in its shelter. I'm assuming the sublimation is wind-driven so open areas will clear first.

sgendreau the newbie
from Boston, lots of drifting there

Posted by: Geert Oct 30 2009, 06:05 PM

The fact that the parachute and heatshield as yet seem to be completely hidden doesn't bode well for all attempts to find any sign from MPL, but it might well be just the poor light and we might see them again once the summer advances a bit further.

But if the polar frost is indeed able to hide the parachute under a layer of dust after one winter, then it might explain why no clear sign of MPL has as yet shown up.

Posted by: djellison Oct 30 2009, 09:09 PM

A signal from MPL is a very very unlikely scenario.

A signal from PHX is just an unlikely scenario.

The last HiRISE image of PHX was not the height of summer so we don't know how visible the chute, backshell and heatshield will be after the ice has fully retreated.

Posted by: Greg Hullender Oct 31 2009, 04:14 AM

QUOTE (djellison @ Oct 30 2009, 01:09 PM) *
A signal from MPL is a very very unlikely scenario.

I'm sure he meant Phoenix. I've made that mistake myself (in reading) three or four times now.

Although, of course, it *is* Halloween, so if things are going to rise from the dead, I suppose this is the time to do it!

--Greg

Posted by: Geert Oct 31 2009, 05:19 AM

QUOTE (djellison @ Oct 31 2009, 05:09 AM) *
A signal from MPL is a very very unlikely scenario.


I didn't mean a (radio) signal, that would indeed be close to impossible. I meant chances of spotting any debris / wreckage from MPL.
As far as HiRise coverage of the MPL landing elips, these are all taken after at least one winter had passed, so if one winter is able to erase most of the traces of PHX then we can expect that the MPL parachute/backshell/heatshield will be equally difficult to spot (at least).

In order to make a convincing case of 'having found debris from MPL' you need to be able to show convincing signs not only of the lander-wreckage, but also of the heatshield, backshell, and parachutes (and all at correct distances from each other), otherwise you just don't have a case in my humble opinion. So the visibility of PHX hardware after one or two winters is a very good measure of what we can expect to see from any MPL debris on HiRise images.

Posted by: djellison Oct 31 2009, 09:30 AM

QUOTE (Geert @ Oct 31 2009, 05:19 AM) *
so if one winter is able to erase most of the traces of PHX.


We don't know if it does or doesn't yet.

Posted by: Adonis Oct 31 2009, 05:21 PM

MRO has almost a polar orbit. Thus, within the same approximate period of time, MRO is able to fly above, and spot, a given place in martian surface.

Phill got the Phoenix MRO images dated last July 30th and August 22th. This makes an approximate period of time of 23 days MRO should be able to fly above Phoenix landing site. Then, should I'm not wrong on this, next days counted in periods of 23 from August 22th were: September 12th and October 5th & 28th, in which theoretically MRO was able to spot Phoenix again..... except some of them it was night time when MRO was flying above Phoenix.

Then, żis it possible that some more recent MRO images of Phoenix landing site were still hidden inside the ammount of data sent by the orbiter? .... or I'm wrong in something I missed.

Thanks.

Posted by: Greg Hullender Oct 31 2009, 06:04 PM

QUOTE (Adonis @ Oct 31 2009, 10:21 AM) *
.... or I'm wrong in something I missed.

MRO has been in Safe Mode since August 26, so it hasn't been taking many (any?) pictures.

http://marsprogram.jpl.nasa.gov/mro/newsroom/pressreleases/20090904a.html

--Greg

Posted by: imipak Oct 31 2009, 06:21 PM

QUOTE (Adonis @ Oct 31 2009, 06:21 PM) *
...something I missed?


Sorry if I misunderstand, but if you're wondering why there are no images on those dates, it's because MRO is still in safe mode.

http://www.planetary.org/blog/article/00002181/

(Edit - sorry for the dupe.)

Posted by: Adonis Nov 2 2009, 12:58 AM

QUOTE (Greg Hullender @ Oct 31 2009, 07:04 PM) *
MRO has been in Safe Mode since August 26, so it hasn't been taking many (any?) pictures.

http://marsprogram.jpl.nasa.gov/mro/newsroom/pressreleases/20090904a.html

--Greg



Thanks Greg.

But MRO web page have published HiRISE images taken in october 7th. So, if is still in safe mode, is capable of doing, at least, some (maybe selective) HiRISE images. And from that date (october 7th) MRO had some opportunities to image Phoenix landing site, which I understand is a science priority since we have there a known hardware to help us see the ammount of frozen ice laying there.

Posted by: elakdawalla Nov 2 2009, 03:00 AM

"Safe mode" usually means no science, and as far as I understand things, no science has been done since August 26. If you're referring to that Hale crater image, it was October 7, 2007. The most recent Phoenix image was taken on August 22, 2009, before the safing event.

--Emily

Posted by: Adonis Nov 2 2009, 06:22 PM

OK. I was wrong at all. Efectively, the image I mentioned was Hale crater, taken in 2007. One less science mystery for me rolleyes.gif and realized there's no recent HiRISE images sad.gif

Thanks Greg, imipak and Emily.

Posted by: Hungry4info Nov 3 2009, 01:09 PM

Here's to wishing re-established contact with Phoenix.
I was bored...

 

Posted by: marsophile Nov 3 2009, 09:02 PM

Upcoming colloquium talk at the SETI Institute:


02/24/2010
Latest results from the Mars Phoenix Lander Microscope

John Marshall, SETI Institute


Presumably, these are anticipated results after regaining contact! laugh.gif

Posted by: climber Nov 5 2009, 09:24 AM

Did we see this one?: http://www.spaceflightnow.com/news/n0911/04phoenix/

Posted by: djellison Nov 5 2009, 09:58 AM

I'm assuming it's the same image Phil used.

Posted by: ugordan Nov 5 2009, 10:10 AM

QUOTE (djellison @ Nov 5 2009, 10:58 AM) *
I'm assuming it's the same image Phil used.

But now it's available in Technicolor™!

Posted by: Phil Stooke Nov 5 2009, 11:47 AM

Yes, same one, and it was in Emily's animation.

Phil

Posted by: ElkGroveDan Nov 5 2009, 03:13 PM

QUOTE
Mars Reconnaissance Orbiter has spotted the Phoenix lander encased in dry ice in the depths of winter on the northern polar plains of Mars

I don't know that I would call it "encased." That patchy setting looks a lot like my http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=16787 from last year (minus the firewood of course).

Posted by: Phil Stooke Nov 5 2009, 03:18 PM

So there actually were two images, July and August - I didn't know that before. The frost patches differ a bit, but it would be possible to combine the two images for a 'super-resolution' or noise-reduced view.

Phil

Posted by: fredk Nov 10 2009, 05:43 PM

Curious story from http://www.skyandtelescope.com/news/69627537.html First the writer states:

QUOTE
The view here gives the impression of frosty patches atop ice-free ground, but that's an artifact of contrast enhancement. In fact, the entire scene is covered with frozen carbon dioxide.

What makes him say that? Why would there be such well-defined brighter patches if the ground was completely covered? The brighter patches don't look like south-facing slopes illuminated by the low Sun - there aren't the corresponding darker areas that you'd expect for the north facing slopes. Besides, I read that the Sun was only at one degree elevation for these images. As we know, the direct, directional illumination from the Sun would be severely attenuated by atmospheric dust when the Sun is that low. Most of the illumination would be diffuse illumination from the sky, which shouldn't produce much contrast on slopes.

Could the CO2 be continuous, but dust is covering much of the CO2, with the bright areas free of dust?

The writer also states:
QUOTE
We'll probably never know how just how much CO2 snow accumulated atop the lander by September, when the coating was likely thickest

That surprized me a bit, since spring equinox was October 26th, and with Phoenix only a few degrees north of the arctic circle, it should've been getting quite a lot of sunlight by September. But still I could believe that the July and August images show essentially the maximum amount of CO2 coverage. So maybe that's what he bases his claim on that the coverage is complete in the images?

Posted by: centsworth_II Nov 10 2009, 05:57 PM

QUOTE (fredk @ Nov 10 2009, 12:43 PM) *
....Most of the illumination would be diffuse illumination from the sky, which shouldn't produce much contrast on slopes.

Could the CO2 be continuous, but dust is covering much of the CO2, with the bright areas free of dust?...
It looks to me like the distinctive surface polygons are present in the dark areas but not visible in the bright areas. If the dark areas were a layer of CO2 covered by a layer of dust, they should be as smooth and featureless as the bright areas.

My question is, are the bright areas flat patches of frost or thicker drifts. If the light is entirely diffused, it may be impossible to tell anything by looking for shadows around the lander.

Posted by: Deimos Nov 11 2009, 05:01 PM

The coldest temperatures occurred/ended at the very end of July, based on past years' TES data. Sublimation will not exceed deposition at the minimum, but rather some time later. The temperatures come up quickly (probably with a feedback involving loss of CO2 ice), so August or maybe September is reasonable. I was surprised too, so I checked. But I imagine no substantive difference from the last image to any other image until the ice starts substantially disappearing.

My impression is the images show icy areas and non-icy areas. But, that's an impression based on an imaged stretched in ways I don't know. It could as easily be thick ice with ice or frost thin enough that the underlying soil influences the albedo. It is, in any case, an albedo contrast. I say that, not because the Sun is so low, but because you can do photoclinometry on the image. The darker areas show their topography quite clearly--I can see features Phoenix saw more clearly than in the orbiter images during the mission (although not as well as the latest pre-dark images). In my opinion, you can even see shading/brightening at the margins of the bright patches. I suggest they are likely just thicker accumulations (ie, drifts). Further, it seems that troughs appear icier than ridges.

When the Sun is very low or below the horizon, diffuse light dominates completely. But twilight skies are not even close to perfectly diffuse, and most of the light comes from 10-20 deg elevation at the solar azimuth +- 20 degrees or so (depends on exact conditions). Some USGS people have done shape from shading on orbiter images of twilit areas, IIRC.

Posted by: vikingmars Nov 14 2009, 02:26 PM

smile.gif For your perusal, here is an high resolution picture showing the Phoenix lander during winter, made from the sum-up of MRO's images ESP_014103_2485_RED.NOMAP.jp2 and ESP_014393_2485_RED.NOMAP.jp2 .
It seems that the lander has lost its "symmetrical" look... (a damaged/collapsed solar panel ?) and that this effect is real and not a processing artifact.


Posted by: Tman Nov 14 2009, 02:39 PM

A high resolution comparison in addition would be nice now smile.gif

Posted by: djellison Nov 14 2009, 02:52 PM

Super resolution isn't really going to work with two push broom images. You're likely introducing more artefacts than improvements. It looks less sharp and phoenix less obvious than the orig two images I'm afraid. So drawing any conclusion from it is unwise

Posted by: vikingmars Nov 14 2009, 02:58 PM

QUOTE (djellison @ Nov 14 2009, 03:52 PM) *
Super resolution isn't really going to work with two push broom images. You're likely introducing more artefacts than improvements. It looks less sharp and phoenix less obvious than the orig two images I'm afraid. So drawing any conclusion from it is unwise


Yes Master !

Posted by: kimmie Nov 23 2009, 09:24 AM

Not the original poster but thanks for the tip djellison. I was looking for more information on this.


Posted by: Hungry4info Dec 14 2009, 03:40 AM

Quick question.

While I don't expect contact with Phoenix to be re-established, I'm curious as to how that would happen if it does. Is DSN time being used to ping Phoenix? Or will Phoenix just ping Earth whenever it wakes up? (If able to)

Posted by: mcaplinger Dec 14 2009, 06:04 AM

QUOTE (Hungry4info @ Dec 13 2009, 07:40 PM) *
Is DSN time being used to ping Phoenix?

Phoenix has no direct-to-Earth link, so I presume that any listening to be done will have to be done by either Odyssey or MRO.

Posted by: nprev Dec 14 2009, 06:13 AM

Hopefully not too far OT, but is that UHF protocol ("Electra"?) for Mars orbiter/lander comm going to be stable for the foreseeable future?

Sort of an interesting system engineering problem to make sure that future missions will be able to talk to long-lived legacy ground assets, yet still incorporate advancements/enhancements.

Posted by: mcaplinger Dec 14 2009, 07:01 AM

QUOTE (nprev @ Dec 13 2009, 10:13 PM) *
Hopefully not too far OT, but is that UHF protocol ("Electra"?) for Mars orbiter/lander comm going to be stable for the foreseeable future?

http://en.wikipedia.org/wiki/Proximity-1_Space_Link_Protocol

It's about as stable as TCP/IP.

Posted by: Hungry4info Dec 14 2009, 01:42 PM

QUOTE (mcaplinger @ Dec 14 2009, 12:04 AM) *
Phoenix has no direct-to-Earth link, so I presume that any listening to be done will have to be done by either Odyssey or MRO.

This makes sense. So, might Phoenix ping MOD or MRO? Or are either of the two instructed periodically to ping Phoenix?
Basically, we're all waiting. But is our wait passive or active?

Posted by: djellison Dec 14 2009, 02:05 PM

Active in either case - they will have to tell MRO / MODY to listen. In Lazerus mode I THINK PHX is sat there waiting for a Proximity 1 Hail. Not sure though.

Posted by: mcaplinger Dec 14 2009, 02:26 PM

Per Mark Lemmon, http://www.met.tamu.edu/mars/lazarus.html

"So, Phoenix woke up and checked: safe mode, yes; low power, yes; clock reset to pre-launch, yes; landing sensor deployed, yes. Action: try to wake up on solar power only, at whatever time of sol that solar power was sufficient. When awake, listen for a beacon on the orbiters for 2 hours. Then, sleep for 19 hours, and try again."

So yes, checking on PHX will require active commanding of an orbiter.

Posted by: Hungry4info Dec 14 2009, 05:09 PM

Alright, thanks.
Is either orbiter being used at the moment for this? If not, when are there plans to try?

Posted by: mcaplinger Dec 14 2009, 05:29 PM

QUOTE (Hungry4info @ Dec 14 2009, 09:09 AM) *
Is either orbiter being used at the moment for this? If not, when are there plans to try?

The link referenced in post 34 of this thread says they will try "early next year". I thought I heard January at one point, can't find that link now.

Posted by: elakdawalla Dec 14 2009, 05:32 PM

January is what Veronica McGregor told me.

Posted by: elakdawalla Jan 11 2010, 11:49 PM

http://jpl.nasa.gov/news/news.cfm?release=2010-008
"Beginning Jan. 18, NASA's Mars Odyssey orbiter will listen for possible, though improbable, radio transmissions from the Phoenix Mars Lander..."

The release includes a new HiRISE image showing Phoenix hardware with lots of frost, dated January 6. I am having a devil of a time matching up the new image to the previous ones (PSD attached of the four previous ones I stacked to make an animation). The http://hirise.lpl.arizona.edu/ESP_016160_2485 does not yet contain any information -- guess they needed to wait till the press release got out. Help! I want to post about this fast but I would really really really like to be able to post a comparison animation flickering among the past views of the lander.

EDIT: Crud, PSD attachment didn't work. GIF attached instead.

 

Posted by: elakdawalla Jan 12 2010, 12:27 AM

Aha, I see what my problem was. I was trying to match the current backshell to the past position of the lander. The image was upside down. rolleyes.gif

New animation is http://www.planetary.org/blog/article/00002302/.

Posted by: Hungry4info Jan 12 2010, 01:21 AM

Well at least one solar panel is still attached. The other looks like it's a different colour. Hopefully not a bad sign. But I'm not sure how to interpret the image.

Posted by: James Sorenson Jan 12 2010, 03:57 AM

I have labeled in the attached image what I think could be Phoenix's Solar Panels covered in frost. But I'm not entirely sure.


Posted by: remcook Jan 12 2010, 09:31 AM

That January Hirise image is stunning, with that combination of frost and land.

Posted by: climber Jan 12 2010, 02:00 PM

One image from jan 6th 2010 here: http://www.spaceflightnow.com/news/n1001/11phoenix/
Found also this quote "Odyssey will first try to listen for Phoenix for three days beginning Jan. 18. The orbiter will fly over Phoenix 30 times next week, monitoring communications frequencies for signals during each pass."

Edited: and, as usual, a much better one from Emily: http://planetary.org/blog/

Posted by: Sunspot Jan 12 2010, 04:56 PM

QUOTE (remcook @ Jan 12 2010, 09:31 AM) *
That January Hirise image is stunning, with that combination of frost and land.


Imagine how it would look from Phoenix ohmy.gif

Posted by: bgarlick Jan 12 2010, 05:29 PM

Does anyone know what the cost/downside is of having Odyssey listening for Phoenix? If there is no cost, why are they waiting until the 18th? Why not start listening immediately whenever Odyssey passes over the Phoenix site? (that way we could determine if Phoenix made it throught the winter as soon as possible and maybe get interesting science results sooner).
Presumably they are delaying the start of the listening and then doing it for only 3 days because using the radio receiver on Odyessey must interfere with other instrumentation or data relay or power consumption or what? Does anyone know what makes using the radio receiver non-zero cost to operate?

Even if Phoenix does not have enought power now to wake up yet, continious listening (assuming it can be done for 'free') would allow us to know *when* Phoenix wakes up (if it ever does which is unlikely) which would be interesting to know.

Posted by: Dominik Jan 12 2010, 06:03 PM

I don't know what the current sun angle is at daytime on that location, but I suspect it's still to low for Phoenix to produce enough energy to wake up. Especially when the solar panels are still covered with frost.

Posted by: mcaplinger Jan 12 2010, 06:13 PM

QUOTE (bgarlick @ Jan 12 2010, 09:29 AM) *
Does anyone know what makes using the radio receiver non-zero cost to operate?

It has to be sequenced, memory has to be allocated for it, etc. I forget if there are flight rules that require some of the other instruments to be off when the UHF is on due to EMI concerns.

And let me remind you that Odyssey doesn't just listen, it has to "hail" the lander by transmitting.

Posted by: MahFL Jan 12 2010, 06:26 PM

The 18th sounds like a good day to me, as it's my 7th Wedding Anniversary smile.gif. woot !

Posted by: marsophile Jan 12 2010, 06:33 PM

Is the remaining frost at this point CO2 or H20?

Posted by: Hungry4info Jan 12 2010, 07:10 PM

QUOTE (Sunspot @ Jan 12 2010, 10:56 AM) *
Imagine how it would look from Phoenix ohmy.gif

Hopefully we'll have images in the not-too-distant future.

Posted by: hendric Jan 12 2010, 10:24 PM

The other thing to think about is that the 18th is the earliest an optimist would expect a reponse. Phoenix stopped transmitting at about the same sun angle, on the way to winter, which means that it's batteries were supplying power and probably extended the time she could send. On the way out of winter, the batteries are going to be dead, and so will not be supplying any extra juice to get her signal out. I'm sure her power management hardware actively controls the battery charging, but I'm not sure how much control the software has over that coming up from a completely dead state, ie the power manager circuit might start trickle charging the battery to raise the voltage well before the CPU comes out of reset. In some cases, such as mobile phones, a charged battery is required for the transmitter to work, since the transmitter uses much more instantaneous power than the wall charger can provide. If you read his description, he does state that the lander waits 19 hours between 2 hour listening windows, for Lazarus mode to cycle the listening window across the whole day because the on-board clock would be reset. For that, the batteries do need a charge. So, my expectation is that the lander will need to wait significantly past the Jan. 18th minimum sol altitude to charge up the batteries enough to last through the night.

Posted by: mcaplinger Jan 13 2010, 12:14 AM

QUOTE (hendric @ Jan 12 2010, 02:24 PM) *
Phoenix stopped transmitting at about the same sun angle, on the way to winter, which means that it's batteries were supplying power and probably extended the time she could send.

I'm not convinced of that since the accounts suggest the batteries were dead at wakeup from running heaters overnight. At any rate, the batteries are very likely to be useless from being frozen at zero charge -- http://www.edn.com/blog/1470000147/post/510028451.html -- so I think we will probably not be able to use them. I think PHX can transmit with a dead battery. One could look at when the ODY overflights are relative to when one would expect max power on the panels to figure out what the most likely recovery time would be.

Posted by: Deimos Jan 13 2010, 03:28 PM

The 2008 use of "Lazarus mode" started when the batteries fully depleted overnight. If the batteries had retained charge through the night thereafter, the 19 hour cycle would have worked--but the batteries depleted repeatedly, resetting the clock, and making all known wake-ups occur in the mid- to late-morning (worst time for UHF overflights). Any spring mission without batteries would start with the same problem; but once (IF) Earth regains control, one can imagine a sequence keeping it awake through mid-afternoon. There would be no overnight data storage: data would be taken prior to a pass and sent in the afternoon, and anything after the last pass would be forgotten. And a functioning spacecraft might not have functioning instruments--surviving a couple likely failure modes does not imply surviving all. (Not too mention my take on the HiRISE images, especially August, does not lead to optimism.)

Still, best case is that there could be some repetitive imaging and MET data, and that would be quite cool. If it comes back, I'd expect (my guesses only) that an especially close late morning overflight might see the first signal; that it would take effort to get a sequence loaded, but another favorable overflight would do it; that science content for the sequence would follow later, and would be repetitive. While trying to gain control, each sol's odds would be bad--but time would be on our side, when it was against us in 2008. Also, the lander would be generating a huge amount of engineering data as it tries to wake up each sol, browns out, and then repeats many times until power is sufficient. But the data would not accumulate over sols.

Posted by: hendric Jan 13 2010, 03:51 PM

Are there any thoughts on making a lander, or perhaps rover, winter-survivable? Larger batteries with an integrated cutoff at mid-charge to survive a freezing? Solar panel petals on the ground, a la Beagle?

Posted by: vikingmars Jan 13 2010, 04:17 PM

QUOTE (hendric @ Jan 13 2010, 04:51 PM) *
Are there any thoughts on making a lander, or perhaps rover, winter-survivable? Larger batteries with an integrated cutoff at mid-charge to survive a freezing? Solar panel petals on the ground, a la Beagle?


smile.gif Yes, that was already studied by NASA in the 70's and the Viking Lander was the perfect fit because it was relying for its energy source on RTG's of which the heat was able to be redirected internally to heat some electronics, batteries and components. They only chose not to land a Viking Lander near the poles i.e. (above 75°N), because they thought that the sample boom and collector head would have been unable to retrieve some samples from premafrost (i.e. soil intermixed with ice)... wink.gif

Posted by: Deimos Jan 13 2010, 05:00 PM

Yes, there are concepts out there. There are still concepts for short-lived summer missions, too. For a fixed (ie, non-MSL-like) budget you have to trade one capability for another, so the choices will vary according to the proposer's goals.

Posted by: PaulM Jan 13 2010, 05:05 PM

QUOTE (Deimos @ Jan 13 2010, 03:28 PM) *
Still, best case is that there could be some repetitive imaging and MET data, and that would be quite cool.

Are you saying that Phoenix's cameras would more likely to work than the motors that drive them and therefore the cameras might only be able to repeat the last photograph that they took back in 2008?

Am I correct in thinking that the Surface Stereo Imager is currently pointing at the sky. I say this because I think that this is the last photo that that imager ever took:

http://phoenix.lpl.arizona.edu/images.php?gID=42523&cID=377

I think that the Robotic Arm Camera may have been left pointing at something more interesting:

http://phoenix.lpl.arizona.edu/images.php?gID=42206&cID=375

Of course it is possible that these cameras were successfully commanded to turn to something else after taking these pictures and so Surface Stereo Imager repetitive imaging might be more interesting?

Posted by: Deimos Jan 14 2010, 04:55 PM

One principle that guides my expectations is that if one improbable thing happens, that does not imply all more probable things happen as well. So, the if the solar panels and all other critical path elements work, anything else might still fail. If the CCDs and imaging electronics work, the motors might still fail. But I do expect that if we ever take more pictures, we could likely point them. I think that would be critical--the camera is aimed down, fully stowed.

However, a lazarus mission would not allow new sequences each day. Planning for post-sol-151 ops was aimed at one or few repetitive monitoring sequences. First, the work that goes into a lazarus day is more than what a normal day needed, and could requires days on Earth--if the full ops team were restored. Getting a sequence on-board that can be read on wake-up is risky, and frankly a lot can be gained by well-designed repetitive work. Also, much of the onboard infrastructure that made sequencing do-able will not function. Second, the conditions of a lazarus day are poorly determined--when you plan, you do not know if the first activity is at 8 am or 11 am. You might have to wait 3 hours to move the camera without heating, or heat so long you risk damage if you guess wrong. The comm pass might come 5 hours after wake-up or 9 hours after wake-up. The same unknowns apply every day. Frankly, wake-up could happen more than once in a day, with non-graceful shutdowns in between, so you're recovering from an unknown state. Always. Third, any activity done has to be low cost and borrow people from other highly-stressed projects (and some are simply not available). We may not be able to change from what was planned in November 2008; of course, imaging modules are somewhat plug 'n' play (meaning they might change from November, not day-to-day).

So, you might be able to include a small panorama in the sequence--and then see that pan every day. There were more creative ideas floating around, but creative = risky and difficult. I suppose risk tolerance might be a wee bit higher these days... So, things we might see include (over-the-top optimist's list): MET, which would be able to use its own flash, giving PT data for most awake-time; TECP (air); daily RAC rgbn image at Alviss; SSI set (full-frame telltale, frost-spot(s), cal/magnet/illumination target, sky); lidar. Unlike normal ops, the camera is never stowed and never uses a solar filter.

Posted by: hendric Jan 14 2010, 10:24 PM

If Phoenix does make it through Lazarus mode, could continuous sunlight during the summer allow for more robust operations? (I know, "I smell a whole lotta 'if' coming off this plan" smile.gif )

Posted by: Deimos Jan 15 2010, 06:31 PM

Continuous sunlight could be a game changer, depending on the list of what still works (also, presumably, the success of some proposed mission of opportunity to NASA). Plenty of time to think about that later. smile.gif Regardless of what's happen ing with comm, there really is no formal contact among the science team--actually, no formal science team any more.

Posted by: Zvezdichko Jan 16 2010, 02:23 PM

Phoenix website was updated for a first time after a long hiatus:

http://phoenix.lpl.arizona.edu/index.php

Posted by: climber Jan 18 2010, 10:42 PM

So, today's the day!

Posted by: Dominik Jan 19 2010, 09:58 PM

I've checked the JPL and NASA sites and even the Phoenix Twitter channel and so far there seems to be no news at all.

A fresh (2-3 days old) picture of the landing site would be great to check, how much ice is left that could cover the solar panels. If the situation is similar to the one in the latest HiRise image, then I think it's very unlikely that the lander already produces enough power to communicate.

Posted by: centsworth_II Jan 19 2010, 11:58 PM

QUOTE (Dominik @ Jan 19 2010, 04:58 PM) *
I've checked the JPL and NASA sites and even the Phoenix Twitter channel and so far there seems to be no news at all.
http://www.bautforum.com/space-exploration/16616-phoenix-mission-9.html#post1663507 The news is simply, 'We're trying, nothing yet.'
'

Posted by: Dominik Jan 21 2010, 11:53 AM

Just a short update, for those who don't follow the NASAJPL Twitter channel:

No signal from @MarsPhoenix after 11 listening passes completed Mon./Tues. Odyssey will be "all ears" during 19 more passes this week.

Posted by: MahFL Jan 21 2010, 03:26 PM

Thank you for the update. One point though, Oddy does hail Phoenix actively though doen't she ?

Posted by: ElkGroveDan Jan 21 2010, 03:37 PM

Oddy? I'm not sure that's an approved nickname here rolleyes.gif

Posted by: Deimos Jan 21 2010, 05:00 PM

Yes, ODY hails, while theoretically PHX listens and responds to hails.

Posted by: Dominik Jan 22 2010, 12:12 AM

I think, this is the last update from NASAJPL until February...

Listening campaign for @MarsPhoenix is over for now, w/ no signal detected. Odyssey will listen again in Feb & March when sun is higher.

Posted by: vmcgregor Jan 22 2010, 10:41 PM

For the January attempts, Odyssey was only listening and not hailing.
Odyssey will hail Phoenix during the February and March campaigns.

Posted by: mcaplinger Jan 23 2010, 12:00 AM

QUOTE (vmcgregor @ Jan 22 2010, 02:41 PM) *
For the January attempts, Odyssey was only listening and not hailing.

Is there a source for this information? As best I can tell from this document -- http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/39934/1/06-1429.pdf -- PHX will never send without receiving, so ODY listening without hailing is useless.

Posted by: vmcgregor Jan 23 2010, 09:11 AM


It's the way the Lazarus mode works. The source is the Phoenix mission team at JPL (originally from Chris Lewicki and Barry Goldstein). The chief telecommunications engineer for the Mars Exploration Program, Chad Edwards, who led the January listening campaign, confirms: "Phoenix's fault mode would have it transmit to any overhead orbiters - without needing to be hailed - during portions of each 2 hr wake-up session (in between 19 hr hibernation periods). We do not need to hail Phoenix to trigger that behavior."

Posted by: marsophile Jan 26 2010, 09:16 PM

Assuming Phoenix in Lazarus mode initially goes through a "Goundhog Day" state where it wakes up with a clean slate, tries immediately communicating, runs out the battery, and repeats the next day (instead of trying at various times), would the recent attempts to pick up a signal have coincided with the likely transmit times? What is the local time at the PHX site during the ODY passes?

Posted by: Deimos Jan 27 2010, 03:41 AM

I don't know the details of the passes, but expect they had a reasonably good sampling of local time. It's around a 5AM/PM orbit, but the polar latitude makes many more times accessible. During the mission, it was occasionally possible to use 3 or 4 consecutive ODY passes (every two hours through the afternoon and evening in that case), and that was for a higher bit-rate than would be in play now.

Hmm. 30 passes in ~3 sols would be all or most opportunities--you could get roughly every hour of the sol, with some resampling, with numbers like that.

Posted by: mcaplinger Jan 27 2010, 03:57 AM

QUOTE (Deimos @ Jan 26 2010, 07:41 PM) *
30 passes in ~3 sols would be all or most opportunities--you could get roughly every hour of the sol, with some resampling, with numbers like that.

Right, but each pass only lasts a max of 7-10 minutes, and I don't know what duty cycle of transmission they were using (since I can't find any documentation that such a mode even existed.) Maybe they send tone for a few seconds every few minutes? Mark, do you know anything about this mode?

Posted by: Deimos Jan 27 2010, 04:09 PM

Having refreshed my memory, I have a bit more info. The first confirmed lazarus communication was sol 154 in a 5:18 AM pass, lasting about 2 minutes. Phoenix was described as being in a mode of continuous communications attempts over 2 hours or until power runs out. The next sol, a signal was seen at 8:20, but was faint (ODY was low in the sky and the path was long). The next sol, the 13:19 pass worked ( 12 minutes!) giving a record of many, many unsuccessful attempts to wake up and a power state that would not survive the night (again). An early AM pass had apparently showed some sort of signal, too. The last signal was detected (without data) at 157/8:24. After that, it was never clear whether the lander was trying to awaken, and failing; awake at unfortunate times; or had entered a particular (permanently) unrecoverable state. So, I think the intent is constant comm for most of 2 hours, which uses many W-hrs, but it may use <10 minute cycles of shorter attempts.

Posted by: Deimos Feb 23 2010, 03:05 PM

Rumor has it the second ODY search is underway, with ~60 contact attempts this week.

Posted by: marsophile Feb 24 2010, 05:46 PM

http://www.jpl.nasa.gov/news/news.cfm?release=2010-063

10 down, 50 to go for this month's campaign.

Posted by: Hungry4info Feb 27 2010, 10:20 AM

Not much ice in the area now.
http://www.nasa.gov/mission_pages/phoenix/images/phoenix20100226.html

Not going to claim certainty on this, but it really looks to me like the solar panels broke off.

 

Posted by: djellison Feb 27 2010, 11:10 AM

I can read it either way. The fact that there are two white patches just south of where the arrays are would to me at least, infer shadowing by the arrays hiding those areas from sublimation. I THINK I can see something where the arrays should be. I just don't know.


Posted by: Hungry4info Feb 27 2010, 11:38 AM

QUOTE (djellison @ Feb 27 2010, 05:10 AM) *
I THINK I can see something where the arrays should be. I just don't know.

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.

Posted by: SteveM Feb 27 2010, 05:05 PM



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

Posted by: Hungry4info Feb 28 2010, 01:32 AM

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!

Posted by: MahFL Mar 1 2010, 06:21 PM

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

Posted by: briv1016 Apr 4 2010, 09:18 AM

Third and final communication attempt to begin on http://www.nasa.gov/mission_pages/phoenix/news/phx20100402.html.

Now I'm not sure about the credibility of this source, but according to http://www.universetoday.com/2010/03/31/nasa-a-possible-reprieve-for-phoenix/ they might be considering a fourth communication attempt in May around the solstice. (Assuming the one next week fails.)

Posted by: ElkGroveDan Apr 4 2010, 04:25 PM

QUOTE (briv1016 @ Apr 4 2010, 02:18 AM) *
Now I'm not sure about the credibility of http://www.universetoday.com/2010/03/31/nasa-a-possible-reprieve-for-phoenix/,

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.

Posted by: briv1016 Apr 14 2010, 03:35 AM

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/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=992

Posted by: vikingmars Apr 14 2010, 08:12 AM

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 sad.gif
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 unsure.gif
I'm now waiting to see the next HiRise images...

Posted by: marsophile Apr 14 2010, 03:16 PM

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.

Posted by: ElkGroveDan Apr 14 2010, 03:34 PM

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.

Posted by: Hungry4info Apr 14 2010, 08:28 PM

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)


 

Posted by: Explorer1 Apr 14 2010, 09:22 PM

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

Posted by: Hungry4info Apr 14 2010, 09:52 PM

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.

Posted by: helvick Apr 14 2010, 10:20 PM

The CO2 ice loading scenarios for mid winter were pretty severe - I pulled some numbers in a post quite some time back ( http://www.unmannedspaceflight.com/index.php?showtopic=5208&view=findpost&p=117877 ) 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.

Posted by: Hungry4info Apr 15 2010, 12:03 AM

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

Posted by: DFinfrock Apr 15 2010, 12:17 AM

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

Posted by: Explorer1 Apr 15 2010, 12:34 AM

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!

Posted by: jekbradbury Apr 15 2010, 12:55 AM

QUOTE (helvick @ Apr 14 2010, 05:20 PM) *
toppled rover

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

Posted by: James Sorenson Apr 15 2010, 04:49 AM

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.

Posted by: akuo Apr 15 2010, 10:19 AM

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.

Posted by: centsworth_II Apr 15 2010, 12:48 PM

QUOTE (akuo @ Apr 15 2010, 06:19 AM) *
As far as I can see from the animation, the lander's shadow hasn't moved very much at all....
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?

Posted by: nprev Apr 15 2010, 12:55 PM

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.

Posted by: centsworth_II Apr 15 2010, 01:02 PM

QUOTE (nprev @ Apr 15 2010, 08:55 AM) *
...Would be nice to get a pic with a lower Sun angle...
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.

Posted by: vikingmars Apr 15 2010, 01:46 PM

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... huh.gif

Posted by: elakdawalla Apr 15 2010, 01:51 PM

QUOTE (James Sorenson @ Apr 14 2010, 08:49 PM) *
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.

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.

Posted by: vikingmars Apr 15 2010, 02:13 PM

QUOTE (elakdawalla @ Apr 15 2010, 03:51 PM) *
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 ! laugh.gif

Posted by: ElkGroveDan Apr 15 2010, 02:16 PM

QUOTE (vikingmars @ Apr 15 2010, 06:46 AM) *
(i) has it moved when the ice buit up or sublimated (s/c pushed aside) or just "slided" on it ?


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.

Posted by: ugordan Apr 15 2010, 02:27 PM

QUOTE (vikingmars @ Apr 15 2010, 04:13 PM) *
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 ! laugh.gif

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. ph34r.gif

Posted by: djellison Apr 15 2010, 02:39 PM

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.

Posted by: Hungry4info Apr 15 2010, 02:44 PM

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.

Posted by: marsophile Apr 15 2010, 03:28 PM

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.

Posted by: nprev Apr 15 2010, 03:32 PM

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?

Posted by: Hungry4info Apr 15 2010, 05:13 PM

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.

Posted by: Deimos Apr 15 2010, 07:00 PM

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.

Posted by: ElkGroveDan Apr 15 2010, 10:04 PM

Thanks Mark for the informed input on both topics.

Posted by: fredk Apr 18 2010, 02:44 PM

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.

Posted by: Tesheiner Apr 18 2010, 04:18 PM

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.

Posted by: Hungry4info Apr 18 2010, 04:30 PM

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

Posted by: fredk Apr 18 2010, 04:42 PM

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

Posted by: Deimos Apr 18 2010, 08:24 PM

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.

Posted by: centsworth_II Apr 19 2010, 07:41 AM

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?

Posted by: centsworth_II Apr 19 2010, 07:44 AM

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

Posted by: Paolo May 14 2010, 08:00 AM

http://www.jpl.nasa.gov/news/news.cfm?release=2010-163 form 17 to 21 May

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