Phoenix - spring images, HiRISE views of Phoenix after the long, long winter Options

[James Sorenson]

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.

[remcook]

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

[climber]

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/

[Guest_Sunspot_*]

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

Imagine how it would look from Phoenix

[bgarlick]

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.

[Dominik]

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.

[mcaplinger]

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.

[MahFL]

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

[marsophile]

Is the remaining frost at this point CO2 or H20?

[Hungry4info]

Imagine how it would look from Phoenix

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

[hendric]

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.

[mcaplinger]

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.

[Deimos]

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.

[hendric]

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?

[vikingmars]

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?

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)...