[FPSPACE] Spirit rover's power is running down, due to dust storms

agzak at optonline.net agzak at optonline.net
Wed Nov 12 11:11:50 EST 2008

It seems that some relatively simple solutions such as rotating or blowing solar panels with cold gas could resolve the problem and prolong these missions. I am wondering if anything like that is considered for future spacecraft. (Of course, placing an RTG on the rover eliminates the problem altogether).

Anatoly Zak

----- Original Message -----
From: Peter Pesavento <pjp961 at svol.net>
Date: Wednesday, November 12, 2008 11:02 am
Subject: [FPSPACE] Spirit rover's power is running down, due to dust storms
To: fpspace at friends-partners.org

> >From the Los Angeles Times
> http://www.latimes.com/news/printedition/asection/la-sci-rover12-
> 2008nov12,0,4968289.story
> NASA's Mars rover Spirit imperiled by dust storms
> The craft is dangerously low on power because of dust covering its 
> solararrays. News of the problem comes a day after NASA declared an 
> end to the
> Phoenix polar mission.
> By John Johnson Jr.
> November 12, 2008
> Massive Martian dust storms are threatening the survival of NASA's 
> Spiritrover, which has been exploring Mars for almost five years 
> but is
> dangerously low on power. 
> Spirit last communicated with Earth on Sunday, when it reported 
> that its
> solar arrays had produced just 89 watt-hours of energy, which is 
> much less
> than the rover uses in a day. 
> It's also the least amount of power that either Spirit, or its twin,
> Opportunity, has produced over the entire life of the mission on 
> Mars, which
> began in January 2004. 
> John Callas, the rover project manager at the Jet Propulsion 
> Laboratory in
> La Cañada Flintridge, said the rover's survival might be in 
> jeopardy because
> the dust-covered arrays were producing only a third as much power 
> as they
> were capable of, even before the latest dust storms hit. The storms 
> of the
> last few days have reduced the output even more, to 26.5%, he said. 
> The announcement of Spirit's problems came a day after NASA 
> declared an end
> to the Phoenix mission near Mars' north pole, the first to sample 
> ice on an
> alien planet. Dust storms, and the approach of winter in the northern
> hemisphere, are blamed for Phoenix's demise. 
> As for Spirit, Callas said he believed the low power levels 
> probably tripped
> a built-in fault-protection system, which automatically disconnects 
> nearlyall the rover's electronics from its batteries to keep them 
> from draining
> completely.
> When that happens, mission managers on Earth lose control of the 
> vehicle. 
> Ideally, after a low-power shutdown, the rover will periodically 
> check to
> see whether the batteries have recharged. If they have, it resumes 
> normaloperations. 
> "The best chance for survival for Spirit," Callas said, is to avoid a
> low-power shutdown, from which it might not awake. 
> To avoid draining the batteries, mission managers sent a message to 
> therover Tuesday, ordering it not to communicate with Earth until 
> Thursday. 
> By then, NASA officials hope, the dust storms will have cleared and 
> thesolar panels will be producing more power. 
> After spending much of the southern hemisphere winter parked, 
> Spirit had
> only started driving again when the dust storms hit. 
> The rover is currently halted at a geological feature called Home 
> Plate. 
> Meanwhile, Opportunity, which has not been compromised by the dust 
> storms to
> the same extent, is driving to a deep crater. 
> The rovers have far outlasted their original life expectancy of 90 
> days. 
> During their time on Mars, they have drilled into rocks and taken 
> picturesof erosion patterns that proved that large parts of the Red 
> Planet were once
> covered by seas or lakes. 
> Today, the surface is much too cold for water to be in liquid form,
> scientists say. 
> Scientists are now using the rovers to understand how the planet 
> changedfrom a more temperate world to a barren rock.

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