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Mars NASA Space

Mars Rover "Spirit" In Danger 222

Posted by kdawson
from the my-kingdom-for-a-sunbeam dept.
Riding with Robots writes "Just days after announcing that the Mars Phoenix Lander has met its icy demise, NASA reports that a dust storm has left the rover Spirit on the edge of power failure. During one recent Martian day, the robotic geologist's solar array produced only 89 watt hours of energy, the lowest output by either rover in their nearly five years on Mars. Mission managers are taking steps to protect the hardy, battle-worn spacecraft, but the agency describes Spirit's status as 'vulnerable.'"
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Mars Rover "Spirit" In Danger

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  • by UnknowingFool (672806) on Wednesday November 12, 2008 @02:05PM (#25736001)
    Both rovers were designed for a 90 Mars day (sol) mission. The difference between Earth days and Mars days is that sols are 24.6 hours long. Opportunity is on Sol 1710 or so and Spirit is on Sol 1730. Both rovers have lasted almost 20 times longer than originally designed.
  • by Muad'Dave (255648) on Wednesday November 12, 2008 @02:07PM (#25736029) Homepage

    The timing has a real Obama's-grandmother vibe, you know?

    Did Obama's grandmother have wheels? If so, they'd have called her a wagon.

  • by Anonymous Coward on Wednesday November 12, 2008 @02:08PM (#25736041)

    Phoenix is not a rover.

  • Re:Winter? (Score:4, Informative)

    by Kjella (173770) on Wednesday November 12, 2008 @02:14PM (#25736121) Homepage

    Or is Spirit near the equator / other hemisphere? I know the Phoenix shutdown is at least partly due to seasonal changes

    Much closer to equator with a combination of winter (expected), dust storm (happens) and wear (by now) ganging up on it but it's in a "survivable" range. Phoenix was sent to the arctic region and never expected to survive winter AFAIK.

  • Re:Anonymous Coward (Score:4, Informative)

    by andawyr (212118) on Wednesday November 12, 2008 @02:16PM (#25736141)

    This was thought about, and discarded. While on the surface it seems like a good idea, in actuality it's incredibly difficult to implement, since the dust on Mar's is so 'sticky' - from what I've read elsewhere, the electrostatic charge of the dust on Mars is very high, and any attempt to scrape it off the solar panels would just move it around, not really remove it.

    Besides, with a two month life expectancy, I think it was determined that they wouldn't need to remove any dust from the solar panels since the rovers would have long since died...

  • Re:Wipers (Score:3, Informative)

    by Kjella (173770) on Wednesday November 12, 2008 @02:20PM (#25736205) Homepage

    Why didn't NASA include a device similar to windshield wipers on the solar panels? It seems that they knew mars was dusty, and it would be a simple thing to add (I'd imagine).

    You'd be wrong. You can find the details in the hundreds of posts on the subject over the last years, in short they figured more scientific equipment would be more valuable.

  • Re:Wipers (Score:4, Informative)

    by confused one (671304) on Wednesday November 12, 2008 @02:21PM (#25736209)
    This has been covered before... Anyway, here's the deal: 1.) The wiper would add weight and cost. 2.) The wiper would require power. 3.) The wiper would eventually wear out. 4.) The wiper might get stuck mid-"wipe", blocking the solar energy incident on the panels. 5.) The wiper would scratch the surface of the solar panel, reducing the amount of absorbed light. Either 4 or 5 would reduce the amount of power generated.
  • Re:Anonymous Coward (Score:5, Informative)

    by UnknowingFool (672806) on Wednesday November 12, 2008 @02:25PM (#25736285)

    NASA probably thought of that, but the issue is how practical any wiper system would be. Unlike automobile wipers, there's no air or water supply to remove the dust. Adding a system to compress air would have added unacceptable weight to the rover and every little bit counts (even if would work reliably under Mars conditions). A water system would have been out of the question. A waterless/airless system then depends on the material you would use. Such a material would have be softer than the panels or they would damage them; however, a softer material (rubber, polypropylene, polyethylene) probably would not survive the extreme conditions of Mars.

    And that's just the survivability aspects. Now factoring the usability aspects: Some sort of arm would have to be long enough to reach all the panels. None of the rovers arms can extend that far so they would have to have been modified. This might add weight and complexity.

    Probably the biggest reason why NASA didn't put one in was the rovers were designed for 90 sol missions. Having them last 5 years is a bonus. Along the way, the Rover team has dealt with the problems that have come with extending the mission beyond the original parameters: wheels no longer work, tools no longer function, dust storms limit power usage, etc. This is one issue that they knew would eventually cause the rovers to cease functioning after a few years.

  • Re:Winter? (Score:5, Informative)

    by ScottMaxwell (108831) on Wednesday November 12, 2008 @02:28PM (#25736333) Homepage

    Isn't this just an effect of reduced sunlight during winter? Or is Spirit near the equator / other hemisphere? I know the Phoenix shutdown is at least partly due to seasonal changes

    Time of year plays into it, certainly; this would be less worrisome at the height of summer. But it's not quite the dead of winter, either (solstice was something like 150 sols ago), so it could be worse.

    Spirit is a little farther from the equator than her twin sister, Opportunity, so winters hit her somewhat harder than they hit Opportunity anyway. (Phoenix is at something like 60 degrees N latitude -- much farther than either rover.) On top of that, she was pretty well dust-covered already, thanks to a previous dust storm and the regular old ongoing dust-deposition process -- dust was blocking about 70% of the light hitting her solar arrays before this storm hit.

    It's possible for this to turn out to be good news. Dust storms are caused by (and, in a classic feedback loop, cause) high winds, so it's possible that the winds will actually clean Spirit off and she'll end up better than she was before. Keep your fingers crossed.

  • by Anonymous Coward on Wednesday November 12, 2008 @02:33PM (#25736439)
    There's also the Mars Global Surveyor (http://mars.jpl.nasa.gov/mgs/ [nasa.gov]), which died (probably of battery failure) after 4x longer life than expected.
  • by DerekLyons (302214) <fairwater@gmai l . c om> on Wednesday November 12, 2008 @02:41PM (#25736575) Homepage

    The Planetary Society blog has a composite picture [planetary.org] of Spirit from two years ago and today which shows starkly just how much dust has accumulated.

  • Re:Anonymous Coward (Score:3, Informative)

    by UnknowingFool (672806) on Wednesday November 12, 2008 @02:49PM (#25736719)

    So, it's just a matter of waiting, if Spirit runs out of power, no big deal, it will stop working, and then if it gets cleaned, it will come back again.

    If the batteries are completely drained, Spirit will probably never run again. Both rovers need a certain amount of power to run their heaters. The heaters keep the sensitive electronics from freezing. The loss of power means that the loss of the electronics. During the previous dust storm, the rovers were put into power save mode to outlast the storms. It worked last time but this time they may not survive.

  • by mykepredko (40154) on Wednesday November 12, 2008 @03:25PM (#25737261) Homepage

    The two rovers were not designed to work for 90 days.

    They were guaranteed to work for 90 days.

    The various components were designed to work no matter what they experienced for 90 days on the Martian surface.

    I suspect that they were designed for the worst possible set of circumstances for 90 days which has allowed them to operate for the much longer time in the actual environment which is more benign than the worst case scenario.

    Regardless of the semantics of the 90 days, the time the two robots have been operating is still an amazing achievement and everybody involved should be very proud.

    myke

  • Re:Winter? (Score:3, Informative)

    by Chris Burke (6130) on Wednesday November 12, 2008 @03:34PM (#25737421) Homepage

    I guess there's still the issue of whether the batteries will fail to operate if they get too cold....

    Yes, that's exactly the problem, and not just for the batteries. The rovers and landers need power just to heat themselves so that their components don't get damaged by the cold. In TFA they even say they've already started sacrificing parts of Spirit to conserve power:

    "Mission controllers are commanding Spirit to turn off some heaters, including one that protects a science instrument, the miniature thermal emission spectrometer, and take other measures to reduce energy consumption."

  • by iamlucky13 (795185) on Wednesday November 12, 2008 @03:52PM (#25737669)
    They were indeed designed to work for almost the worst conditions expected for 90 days, based on what prior landers saw. If you read Dr. Steven Squyre's book Roving Mars (which I highly recommend for any space nerd, even though he wrote it several years too early), he describes at several points how worried they were that dust accumulation was going to kill these things before 90 days were up.

    After talking about wipers, blowers, vibrators, etc. they concluded the best course of action was to just size the panels to produce the minimum required amount of electricity for operations after 90 days of worst-case dust accumulation. An added bonus of this approach was plenty of power to play around with early in the mission (and part of why they've done so well now). Accomplishing this ended up being a huge problem, however, and I think the power team spent weeks trying to figure out a geometery that would provide the needed amount of surface area, but not get in the way of all the other parts while folding down small enough to fit inside the tetrahedral lander platform. They finally got a break when they figured out a set of winglet-like tabs that unfolded from the back of an already folded section of panel.

    The result didn't just solve the problem, it looked freaking awesome. Earlier renders of the rovers had them being nearly square or hexagon shaped, as opposed to the swept-back fighter wing look [seds.org] they have as built. Heck, Steve Jobs is probably even jealous of how sexy the MER's look, and they aren't even trying.
  • by compro01 (777531) on Wednesday November 12, 2008 @04:32PM (#25738251)

    Which is why they are using Watt-hours, which are a unit of energy equal to 3600 joules (1 Joule=1 Watt-second).

  • by Tacticus.v1 (1102137) on Wednesday November 12, 2008 @08:30PM (#25741201)

    Nasa got 17.138 Billion dollars in 2007
    The US military got 527.660 Billion dollars
    10 Billion dollars is spent on iraq each month

    Pick a fucking better target to aim at

Nothing succeeds like success. -- Alexandre Dumas

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