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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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  • Winter? (Score:5, Interesting)

    by chebucto (992517) on Wednesday November 12, 2008 @12:54PM (#25735797) 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

    From the Press Release:

    "NASA's Phoenix Mars Lander has ceased communications
    after operating for more than five months. As anticipated, seasonal
    decline in sunshine at the robot's arctic landing site is not
    providing enough sunlight for the solar arrays to collect the power
    necessary to charge batteries that operate the lander's instruments."

  • by sexconker (1179573) on Wednesday November 12, 2008 @01:01PM (#25735925)

    Viking 1 - orbiter + lander - dead and dead (fuel leak, battery)
    Viking 2 - orbiter + lander - dead and dead (out of gas, bad software update)

    Pathfinder - lander - lost contact in 12 weeks.
    Sojourner - rover - lost contact in 12 weeks.

    Spirit - rover - critically low power, busted wheel
    Opportunity - rover - still roving strong

    Phoenix - rover - dead, but we're still listening

  • by CMF Risk (833574) on Wednesday November 12, 2008 @01:05PM (#25735999)

    Think next time they'll add a cleaning brush attachment for the arm?

  • by F34nor (321515) on Wednesday November 12, 2008 @01:23PM (#25736261)

    These things had a 90 day life span! Next time I think we should send them in pairs so they can help each other out in a pinch.

  • by iamwhoiamtoday (1177507) on Wednesday November 12, 2008 @01:29PM (#25736355)
    actually... if you look at performance and power consumption... it would make sense to run advanced tasks on graphics cards (GPGPUs) then on processors...
  • by iamlucky13 (795185) on Wednesday November 12, 2008 @01:54PM (#25736785)
    It's fall in the northern hemisphere of Mars where Phoenix is located, so it dying was entirely expected, and although it lasted longer than its mission, they were hoping to get a few more weeks out of it. Landing was just a month before the summer solstice, so it had 30 days of conditions that started good and improved, then 130 days of declining conditions. Since it's in the arctic circle, it had complete daylight until a month or two ago, when the sun started setting again.

    Spirit and Opportunity, however, are in the southern hemisphere, and it's early spring. Between the dust on Spirit's solar panels and being about 12 degrees further from the equator than Opportunity, things got a little worrisome for Spirit over the winter, but her minimum power levels at that time were over twice the 89 Watt-hours quoted in the article.

    Low power is slightly less of a concern now than it was then, because the surface temperature should be higher and so electronics should need less heating, but that huge drop in power is probably more than enough to make up the difference. The other potential positive factor is Spirit's batteries had a decent level of charge when the storm started, so if the storm dissipates quickly they'll probably be in the clear. Trying to maintain 89 W-hr for several months, however, could very easily be fatal, so they're trying to use an absolute minimum of power to keep her out of fault mode.

    Spirit actually hadn't moved an inch for several months to save power until a week or two ago. Her team had parked her on a sloped rock face at about a 30 degree angle to square her solar panels to the noon sun over the winter, and because of relatively clear skies, she was even able to take a high resolution panorama [nasa.gov] (link is to an index, not directly to the giant 42 MB image) and do some stationary science. As the sun angle increased, they had just started inching back towards a 20 degree tilt to follow it when the dust storm hit. There's a rather dramatic picture of what that 30 degree tilt [nasa.gov] looks like on the program site.

    As of the last report I've seen, the atmosphere is 69% opaque due to suspended dust (although I believe more than 31% of the sunlight diffuses through indirectly), and the dust coating on Spirit's solar panels is only letting through 32% of of the sunlight that actually reaches them. In the past they'd had good luck with winds cleaning the panels off, but that hasn't happened in a while. The team is hoping that the same seasonal weather that brings on these dust storms will generate a few lucky dust devils.

    Opportunity, on the other side of the planet meanwhile, has been getting 500-600 Watt-hours and averaging about 50 meters per day of progress towards the huge crater Endeavor, which is 12 km away.

    And what nutjob modded the parent as a troll? Sheesh! And to think we probably let that person vote, too.
  • by Anonymous Coward on Wednesday November 12, 2008 @02:14PM (#25737047)

    Pathfinder - lander - lost contact in 12 weeks. Sojourner - rover - lost contact in 12 weeks.

    One interesting little bit of trivia about this joint mission, which was only designed to last for 40 days, is that the Sojourner rover depended on the Pathfinder lander, which carried it down, to relay communications to earth. Pathfinder died first, leaving the poor little Sojourner all on its own, but probably still functional.

    In the event of losing contact, the rover was programmed to try to drive back to where it remembered the lander being and circle it, on the assumption a rock or something was blocking the signal. Last year the Mars Reconnaissance Orbiter photographed and clearly identified Pathfinder, but Sojourner is small enough they aren't sure if they spotted it or not. It's probably a little black spec barely visible halfway between the lander and where it was when contact was lost, meaning it died shortly afterwards. It's impossible to be sure, however, and one of the team members has proposed the whimsical but fun idea that it got confused about its position and took off in a straight line across the country-side. It could be over a kilometer away by now.

    Go WALL-E...err...I mean Sojourner!

  • Re:Winter? (Score:3, Interesting)

    by dgatwood (11270) on Wednesday November 12, 2008 @02:15PM (#25737067) Journal

    That's what never made sense to me. Seems like all it would take is a low voltage cutoff circuit that shuts off power to everything as long as the voltage is below a threshold voltage, and then when the power comes back on, it would boot back up. In fact, most modern battery technologies require such safety measures to prevent the battery charge from getting so low that the batteries won't take a charge (or the cells reverse polarity like NiCd batteries have a habit of doing). I guess there's still the issue of whether the batteries will fail to operate if they get too cold....

  • by Tablizer (95088) on Wednesday November 12, 2008 @02:25PM (#25737273) Journal

    It would be very sad to see Spirit run out of power, but honestly, both the rovers have performed so far beyond their original expectations, it's astounding

    Here's the things one or both rovers have survived so far:

    * Full flash memory
    * Non-rotating wheel
    * Dusty solar panels
    * Stuck in dust dunes
    * Two winters (very cold)
    * Going down and up steep crater slopes
    * A global dust-storm that put power at the edge (about a year ago)
    * Broken joint motor
    * Power leak

    That's nine. If they follow feline conventions, then number 10 will be it.
         

  • by Anonymous Coward on Wednesday November 12, 2008 @03:03PM (#25737823)

    Not trolling, but NASA is an expert at setting expectations low, then milking things for all they're worth when they keep working 'beyond expectations'.

    So, good job, but enough of the 'will only last for 2 months' bullshit already.

  • Re:Winter? (Score:3, Interesting)

    by speroni (1258316) on Wednesday November 12, 2008 @03:20PM (#25738073) Homepage

    Both of the rovers are near the equator. Its just a build up of dust.

    The phoenix lander was near the north pole. It was there checking for ice. The phoenix lander being in the colder region will actually be so cold it will have carbon dioxide freezing onto it. Its unlikely to wake back up in the spring...but possible.

    The cool thing with the phoenix lander is it DID find ice and even saw snow.

  • Re:Options (Score:5, Interesting)

    by jafac (1449) on Wednesday November 12, 2008 @03:30PM (#25738209) Homepage

    Well, I had read about the fear of issues with dust settling on the solar cells; I figured they should have used the same mechanism that NASCAR uses to clear the lenses of the car-cams. A clear, celluloid cover over the cells, which can be rolled-up off of a spool on either side of the cells, and a brush along the top of the spool. Every time dust collects on the cells, the spool winds out a new clear celluloid cover, the dusty bit is brushed off, and rolled up. Next time, the motor rolls the opposite direction.

    Oh well, maybe the next rover will have something like this.

For every bloke who makes his mark, there's half a dozen waiting to rub it out. -- Andy Capp

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