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Space Science

Crash Course in Safely Crashing on Mars 27

Posted by timothy from the go-fast-turn-left dept.
An anonymous reader writes "NASA described today how they prepared for the twin air-bag crash landings on Mars. The sites are Gusev Crater on January 4th and Terra Meridiani on January 25th. The golfcart-sized rovers have double-lined bladders, that must protect against: the equivalent of a forty mile-per-hour crash, compression against a surface of unknown sharpness, impacts repeated in rapid succession up to sixteen times, and the big bounce covering more than half-a-mile. Airbag landings are considered easier than retro-rocket or soft landings."
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Crash Course in Safely Crashing on Mars More

Crash Course in Safely Crashing on Mars

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  • Hmmm... (Score:4, Funny)

    by JofCoRe ( 315438 ) on Wednesday November 05, 2003 @11:47AM (#7396689) Journal
    Airbag landings are considered easier than retro-rocket or soft landings.

    Hey, maybe they should land airliners this way?

    ...and the big bounce covering more than half-a-mile.

    Hmmm... maybe not.. :)
  • Because the two rovers will be operating simultaneously on the surface, scientists monitoring their activities will have to set their clocks to Martian time, not Earth time. In practice, the extra 36 minutes each Martian day makes for a complicated rotation of workers' sleep
    That doesn't make any sense to me. Do the rovers only function well during daylight hours or something?
    • Will the rovers be able to communicate with NASA when Mars has rotated so that the planet is between the rovers and Earth?

    • Yes, they do. They are solar [nasa.gov] powered [nasa.gov]; in fact, the mission lifetime is determined by how long it will take for the solar panels to become degraded by dust cover.

      I attended a lecture about sleep & human performance recently, and this question came up. The best strategy would be to keep the workers in an environment with a light pattern synched to mars time. Unfortunately, this would be very expensive. Even more unfortunately, since Spirit and Opportunity are landing at very different longitudes, the

      • how long it will take for the solar panels to become degraded by dust cover
        What about "windshield wipers?" A quick swish every few hours (or days, whatever) keeps 'em clean{er}. Or a quick shot of compressed air, or something like that?
      • Thanks,
        I guess on Mars you don't have to worry about cloudy (dusty?) days, so they forgo the weight of a serious battery. If its dusty/eclipse/night, they just go out for space brewskis...
      • Since we have a tendency to revert to 25 hour [mcw.edu] circadian cycle anyway, it should be even easier for us to operate on a mars day than an earth day, as long as we don't have our cycle forced to reset by factors such as sunlight or alarm clocks.

        As to the dusty solar panels -- I wonder why they don't build on a robotic arm to brush off the dust? There must be more to it than just dust, or it would seem like a small investment could greatly prolong the life of the mission.
    • I'd say the large solar panels on top of the rovers (and most space equipment) might have something to do with this.
  • "Go that way. Really fast. If something gets in your way... turn."
    • ...and if you run out of ground - one of the multi-kilometer drops at the edge of Valles Marineris [nasa.gov] would be spectacular (being American, the craft would explode when it hit) but even a six-foot edge or hole would probably do - it's too late to stop even if there was no transmission lag. Oh, well.
  • Airbag landings are considered easier than retro-rocket or soft landings

    By whom? I can't find the reference, but I remember reading after the last airbagged probe to Mars where a bunch of reasonably reputable engineers were decrying this approach, and insisting that parachutes were still the best.

    Sure the Martian wind storms would be bad for parachute descents, but it seems like you could mitigate that (this is me speculating now, I don't remember the discussion from the Real Engineers) by either delayi

    • According to the article, the capsules first get slowed down severely by atmospheric friction, parachutes and helper rockets. The airbags are just there to cushion what's left of the velocity when the capsules hit the ground.

    • Re:Air-bag landings (Score:3, Informative)

      by boarder ( 41071 )
      The problem with parachutes on Mars is not so much the wind as the air pressure (or lack thereof). Parachutes in the thin atmosphere have to be very big to slow things down. You also can't pop out a large chute when you are burning in at 20,000 mph. There is a ton of design, testing and re-testing to run up the mission cost. Materials are also more expensive for them. Single point failures also have a larger potential for disaster with a chute system. Recall the air force guy that did the skydive from
      • "this side up ^" payloads,

        Is this really an issue with airbags? I thought that the payload was designed so that it opened up like a flower, and thus any "petal" touching the ground would force the payload to right itself.
  • "The golfcart-sized rovers have double-lined bladders"

    This may be helpful, but wouldn't it be simpler to take a leak before the landing sequence starts?

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