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Sol 150+, Time marches on...
01101001
post Oct 30 2008, 09:16 PM
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Yeah, getting grim.

JPL Phoenix Mission News: Phoenix Mission Status Report (October 30)

QUOTE
NASA'S Phoenix Mars Lander, with its solar-electric power shrinking due to shorter daylight hours and a dust storm, did not respond to an orbiter's attempt to communicate with it Wednesday night and Thursday morning.

Mission controllers judge the most likely situation to be that declining power has triggered a pre-set precautionary behavior of waking up for only about two hours per day to listen for an orbiter's hailing signal. If that is the case, the wake-sleep cycling would have begun at an unknown time when batteries became depleted.

"We will be coordinating with the orbiter teams to hail Phoenix as often as feasible to catch the time when it can respond," said Phoenix Project Manager Barry Goldstein at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "If we can reestablish communication, we can begin to get the spacecraft back in condition to resume science. In the best case, if weather cooperates, that would take the better part of a week."
[...]
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Hungry4info
post Oct 30 2008, 09:46 PM
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I'll side with Stu on this one.

Sure, It'll be sad to see Phoenix go, but when it comes, it comes. We've all known it will die over the winter. Perhaps since we've always known that it'll die from the cold, we've all been preparing ourselves for the inevitable. And perhaps, the rovers are easier for us to identify with. Spirit and Opportunity look alive. The Pancam looks like eyes, the robotic arm is... an arm... and so on. We find it easier to sympathize with the MER rovers than we do a tabletop lander with a bunch of instruments on it. With MER, we can go out and explore, with Phoenix, we're stuck in one spot.

I'll be sad to see it go, but I won't shed a tear. When one of the MER's die, then I'll probably be a bit tearful.
My mother says that praying for a successful launch is silly, "It's just an inanimate object" she says.
Oh she has no idea...


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-- Hungry4info (Sirius_Alpha)
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bgarlick
post Oct 30 2008, 10:58 PM
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> the wake-sleep cycling would have begun at an unknown time when batteries became depleted.

I find this surprising. As I recall, one of the reasons we lost contact [eventually forever] with Mars Pathfinder was because pathfinder's clock got off and earth had no idea when it was communicating. I believe there are other cases of lost space probes because out of out of sync clocks.

Not loosing track of time seems to be of utmost importance. A digital clock requires such miniscule amounts of power (think of those kid science kits where you power a digital clock by sticking wires into a potato) it seems like they would have had a separate power source for the clock for Phoenix (and all post Pathfinder missions). A single, tiny, buttoncell can power a digital clock for a decade!

If, instead, Phoenix still has a correct time reference, but the mode it has gone into was timed relative to when the 'batteries became depleted' that just seems like a silly software error. No matter when a fault happens, the space craft should always communicate at a deterministic time.
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mcaplinger
post Oct 30 2008, 11:11 PM
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QUOTE (bgarlick @ Oct 30 2008, 02:58 PM) *
No matter when a fault happens, the space craft should always communicate at a deterministic time.

It can only do this if it has power to do so. And remember that Phoenix can only communicate when an orbiter is going overhead, which only happens four times per day for a few minutes each time. So communicating at a deterministic (Earth) time is not something that makes much sense in this case, without the lander remembering a lot more stuff than it would be a good idea for it to rely on to remember (like exactly when the passes are predicted to occur for a long time into the future.)

If you do things based on an absolute clock, they had better not fail if that clock goes nuts. It's easier to rely on things you can directly observe.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Guest_Oersted_*
post Oct 30 2008, 11:59 PM
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Too bad they didn't permanently park the arm twisting up one of the solar panels towards the sun... wink.gif
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belleraphon1
post Oct 31 2008, 01:14 AM
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QUOTE (Hungry4info @ Oct 30 2008, 05:46 PM) *
My mother says that praying for a successful launch is silly, "It's just an inanimate object" she says.
Oh she has no idea...


Ah.... what we know is that that "inanimate object" is the incarnation of the dreams, and blood, and sweat, and tears, and years, of love and effort to create a machine to answer a tiny set of questions about this strange universe we find ourselves in.

These machines are at the foci of our yearning to know...

I will feel sad indeed when we no longer hear from Phoenix ..... but she and the mission team wrought every drab of data
they could... and she, like a mayfly, will have lived her life to the fullest.

Craig






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mhoward
post Oct 31 2008, 01:19 AM
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Well said. I would add, one isn't really praying for the inanimate object; one is praying that human understanding may be allowed to advance.
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01101001
post Oct 31 2008, 01:42 AM
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The NASA Phoenix Twitter Feed is sounding sad but brave:

QUOTE
  • Take care of that beautiful blue marble out there in space, our home planet. Iíll be keeping an eye from here. Space exploration FTW! about 6 hours ago from web
  • In case we don't get this chance again, thank you all so much for the questions, comments & good wishes over the mission. It's been awesome. about 7 hours ago from web
    [...]
  • Many questions about next Martian summer and will I wake up? It is beyond expectations. But if it happens you'll be among the 1st to know. about 9 hours ago from web
  • I may go to sleep soon, @lordavon . But my "Lazarus mode" might allow me wake up now and then for short times during next few weeks. about 9 hours ago from web
  • I should stay well-preserved in this cold. I'll be humankind's monument here for centuries, eons, until future explorers come for me ;-) about 17 hours ago from web
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aggieastronaut
post Oct 31 2008, 03:14 AM
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Man, wrapping up some of Phoenix's open-ended projects today nearly made me tear up... :\
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ilbasso
post Oct 31 2008, 03:30 AM
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Now I see well why with such dark flames
your eyes sparkled so often.
O eyes!
It was as if in one full glance
you could concentrate your entire power.
Yet I did not realize - because mists floated about me,
woven by blinding fate -
that this beam of light was ready to be sent home
to that place whence all beams come.
You would have told me with your brilliance:
we would gladly have stayed near you!
But it is refused by Fate.
Just look at us, for soon we will be far!
What to you are only eyes in these days -
in future nights shall be stars to us.

(translated from Friedrich Rueckert, as used in Mahler's Kindertotenlieder)


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Jonathan Ward
Manning the LCC at http://www.apollolaunchcontrol.com
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laurele
post Oct 31 2008, 06:04 AM
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I know this probably sounds like a dumb question, but isn't there any way to put Phoenix into a state of hibernation and then wake it up when the Martian winter is over?
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centsworth_II
post Oct 31 2008, 06:14 AM
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As I understand it, the extreme cold will physically break electrical circuits and kill batteries.
Phoenix will actually be encased in dry ice (frozen CO2).
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ElkGroveDan
post Oct 31 2008, 06:19 AM
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.....however in the extremely unlikely event that Phoenix does survive it has something they call the Lazarus mode where it would signal its condition if it was still functioning when solar power levels rise next Martian spring.


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If Occam had heard my theory, things would be very different now.
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centsworth_II
post Oct 31 2008, 06:30 AM
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QUOTE (ElkGroveDan @ Oct 31 2008, 02:19 AM) *
.....Lazarus mode where it would signal its condition if it was still functioning...

I suppose the most likely positive result would be detecting a slight sign of life in Phoenix, but no sight, hearing, taste, smell, sense of touch or ability to move. Kind of a vegetative state.
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paxdan
post Oct 31 2008, 09:22 AM
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Wired RIP @MarsPhoenix: The Twitter Epitaph Contest
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