Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ Phoenix _ Power Levels

Posted by: briv1016 Sep 5 2008, 07:12 PM

This has been discussed within other threads before but considering how important it is becoming, I think it deserves its own thread.

Since we are now on sol 100 with fall fast approaching, I was wondering if anyone has been keeping track of the power levels for Phoenix. Any idea when they might have to add recharging sols into the sol-to-sol planning? How low might the power levels be on Sept 30 and will that affect further mission extensions?

Posted by: 1101001 Sep 5 2008, 08:39 PM

I don't know where the power readings are reported.

Apropos the general situation: http://www.space.com/scienceastronomy/080828-phoenix-postcard.html (August 28)

QUOTE

The amount of power generated by Phoenix's two solar arrays is also on the decline, with the probe currently generating about 2,500 watt-hours each day - or about 1,000 watt-hours less than when it landed - because of waning sunlight. The absolute minimum needed for Phoenix to perform the most basic operations is about 1,000 watt-hours, mission managers said.

"We're predicting that's the end of mission," Goldstein said, adding that current projections put that power benchmark in November.

Posted by: CosmicRocker Sep 7 2008, 05:47 AM

I suspect this has already been explained on this forum, but I can't recall it. Is there any possibility that this amazing device might be revived when the sun returns to these northern regions of Mars' next year, or is "lights out" the end of the road for Phoenix?

Posted by: briv1016 Sep 7 2008, 07:25 AM

QUOTE (CosmicRocker @ Sep 7 2008, 01:47 AM)

Isn't this entire region covered by solid CO2 ("dry ice") in the winter. I think that would spell the end for any electronic device.

Posted by: Zvezdichko Sep 7 2008, 07:56 AM

QUOTE

The absolute minimum needed for Phoenix to perform the most basic operations is about 1,000 watt-hours, mission managers said.

Isn't that very much compared to MERs?

Posted by: djellison Sep 7 2008, 10:07 AM

QUOTE (Zvezdichko @ Sep 7 2008, 08:56 AM)

Isn't that very much compared to MERs?

It's also older electroncis compared to MER, and far more challenging conditions ( requiring more heating etc )

And, for what I think is probably the 10th time on this forum. Yes - there is a 'lazurus' code onboard incase it wakes up in the spring, but no one realistically expects it to survive.

Doug

Posted by: Zvezdichko Sep 7 2008, 10:22 AM

Sorry. I forgot that many of its parts are actually old (Mars 2001 Surveyor lander, etc)...

I also don't expect it to survive. Even the NEAR spacecraft didn't.

Posted by: djellison Sep 7 2008, 10:34 AM

I'd also add that the compact, well insulated WEB of the rovers probably performs a far better job of insulating itself than the Phoenix design.

Doug

Posted by: Zvezdichko Sep 7 2008, 10:52 AM

It's probably right, but for a mission of this type - when the most basic instruments have single-use ovens and beakers, all task will be accomplished until the sun fully sets.

I'll be very interested to see the MET and LIDAR functioning up to this time, though .

Posted by: Deimos Sep 7 2008, 01:20 PM

QUOTE (djellison @ Sep 7 2008, 10:34 AM)

I'd also add that the compact, well insulated WEB of the rovers probably performs a far better job of insulating itself than the Phoenix design.

Not my specialty, but I imagine so. The PHX EBs were originally spec'd for an equatorial mission, and they have no RHUs. They're beefed up enough that energy dissipation into the EBs occasionally affected operations due to the need to avoid being too hot (as with the MERs). But of course the PHX payload could dump more energy into the boxes than the MERs could. Spirit demonstrates another difference--the rovers can sleep 23.9 h /sol if needed. PHX requires periodic, brief housekeeping wakeups like Mars Polar Lander would have needed. The way PHX works is suited to one of the goals, getting diurnal coverage of the atmospheric state.

So on the face it is shocking to see that PHX survival energy is comparable to the best days of Spirit's life ... but that is just the difference between the missions. The PHX panels were designed for PHX (OK, M'01, but for the way the lander uses energy) -- lots of area, no worries about mobility. But the MER's of course would need much more energy per day with no RHU and a peak temperature of -30 or so, even ignoring the other considerations.