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'Something' Cleaning Mars Rover

Posted by CmdrTaco on Thu Dec 23, 2004 05:06 PM
from the interplanetary-rose-royce dept.
Space
bluenirve writes "'Something' has been cleaning the solar panels of the Mars rover Opportunity. "NASA's Mars rover Opportunity seems to have stumbled into something akin to a carwash that has left its solar panels much cleaner than those of its twin rover, Spirit. A Martian carwash would account for a series of unexpected boosts in the electrical power produced by Opportunity's solar panels.""
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[+] Mars Winds Clean Spirit's Solar Panels Again 269 comments
Titoxd writes "In a blast from the past, NASA reports that Spirit's solar panels have received a much-needed cleaning courtesy of the Red Planet. The report states, 'The cleaning boosts Spirit's daily energy supply by about 30 watt-hours, to about 240 watt-hours from 210 watt-hours. The rover uses about 180 watt-hours per day for basic survival and communications, so this increase roughly doubles the amount of discretionary power for activities such as driving and using instruments.'"
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  • They looked for the dirt (Score:5, Funny)

    by Adam9 (93947) on Thursday December 23 2004, @05:08PM (#11172195) Journal
    When NASA scientists had the rover examine its solar panels for dirt, it replied, "Nothing for you to see here. Please move along."

  • Yesterday's News. (Score:5, Informative)

    by Vaevictis666 (680137) on Thursday December 23 2004, @05:08PM (#11172197)
    Dupe from Yesterday [slashdot.org]

  • Even Mars has homeless (Score:3, Funny)

    by Anonymous Coward on Thursday December 23 2004, @05:09PM (#11172209)
    Isn't it clear that homeless Martians have newspapers to clean the panels too?

  • That Martian is going to get pissed.... (Score:5, Funny)

    by Neologic (48268) on Thursday December 23 2004, @05:10PM (#11172220)
    That Martian is going to get pissed when the probe doesn't give him a tip.

  • Just goes to show... (Score:5, Funny)

    by Anonymous Coward on Thursday December 23 2004, @05:10PM (#11172225)
    Women are from Mars.

  • Nitrogen (Score:3, Interesting)

    by panxerox (575545) * on Thursday December 23 2004, @05:11PM (#11172232)
    I've always wondered why they never put a little bottlie of compressed nitrogen on the rover with nozzels pointed at the panels. Press a switch on earth and pffftt! dust be gone!

    • Re:Nitrogen (Score:5, Insightful)

      by prisoner-of-enigma (535770) on Thursday December 23 2004, @05:37PM (#11172500) Homepage
      Perhaps it's because an exploding bottle of nitrogen would probably total the probe. Always consider what failure of the doo-dad would do to the overall mission before including the doo-dad. Dirty solar panels are one thing, shredded panels is another.

    • Ultrasonic cleaning (Score:5, Interesting)

      by EvilMidnightBomber (778018) on Thursday December 23 2004, @10:16PM (#11173981) Homepage
      I had almost exactly the same problem when prototyping my robot lawn mower. (crappy pic in profile) The first rev. used optical interrupters to sense a cut grass edge, and these would rapidly become unusable due to dust. I ran through the feasibility of using such an onboard(liqufied) gas tank, but the ratio of functionality to weight is king in any mobile (and especially spaceborne) app and this falls short on that mark (beside being non-renewable). Wipers (and worse yet the geared motor to drive them) are similarly bulky, and unless you're using diamond coated optics,(no water here to lubricate things) wiping the dust eventually produces hazing due to microscratches. The solution I found was to incorporate the equivalent of an ultrasonic parts cleaner. A cheap high-powered motorola peizo tweeter from rat-shack acoustically coupled to the optics support bar and driven at 40khz does an incredible job of knocking off ALL the loose dust, and it's very light weight. The rover could do the same thing by tilting it's panels vertically and then letting rip with the u-sound. About one x-ducer per square meter is all it would take.

      • Re:Nitrogen (Score:4, Informative)

        by WhiteBandit (185659) on Thursday December 23 2004, @08:36PM (#11173415) Homepage
        Hmm, I fubar'd my link. Anyway, my post SHOULD have said:

        Or maybe not [cnn.com]:


        Steve Squyres, the Mars rovers principal investigator, said the rovers' designers deemed the additional weight of adding wipers or blowers to the solar panels was not worthwhile. Instead they increased the size of the panels to maximize the power input.

      • "Or maybe $5 windshield wipers would do?"

        What amazes me about this suggestion (which has been posted ad nauseum) is the assumption that NASA engineers didn't consider this.
  • Is NASA going to have a stinky, unwashed, unshaven martian approach the camera and ask for change?

  • I don't know why (Score:4, Interesting)

    by eclectro (227083) on Thursday December 23 2004, @05:12PM (#11172240)

    they just didn't put a windshield wiper with a mister on the rovers.

    Then there would be water on Mars!

  • it's obviously love on mars (Score:3, Funny)

    by swschrad (312009) on Thursday December 23 2004, @05:12PM (#11172246) Homepage Journal
    maybe one of the "lost" landers has a crush on opportunity ;) OK, enough slashdot, back to the egg nog....

  • Beagle 2 (Score:3, Funny)

    by piquadratCH (749309) on Thursday December 23 2004, @05:13PM (#11172257)
    So THAT's what Beagle 2 is doing all the time up there...

  • Design (Score:5, Interesting)

    by FiReaNGeL (312636) <<fireang3l> <at> <hotmail.com>> on Thursday December 23 2004, @05:17PM (#11172297) Homepage
    NASA engineers decided not to put wipers on the solar panels, because it would have been too much trouble / added too much weight. I guess they're pretty happy with their decision now, with the 'unexpected' cleaning events...

      • Re:Design (Score:3, Informative)

        by Sparr0 (451780)
        you do realize the cost of sending payload to the martian surface is measured in millions of dollars per ounce right? a 3 ounce arm would NOT have been worthwhile, considering all the extra (redundant) mechincal support it would have required, as well as software.

  • Explanation (Score:5, Funny)

    by JustinXB (756624) on Thursday December 23 2004, @05:22PM (#11172359)
    http://ars.userfriendly.org/cartoons/?id=20041107 [userfriendly.org]
        • Ok. Here's an explanation. The rover(s) are losing power because dust is settling on the solar collectors. But in one case, there was this magical boost in power output by 5%. The first thing you would think of is that more sunlight is getting to the photo cells. Some Martian kid came by and, with his finger/tentacle/whatever, wrote "Wash Me" on one of the panels, just like kids do here on earth with dirty vehicles.

  • I told them.... (Score:5, Funny)

    by Audacious (611811) on Thursday December 23 2004, @05:32PM (#11172445) Homepage
    I told those peskey custodians to NOT clean the rover while it was on the set!

  • Mystery solved (Score:3, Funny)

    by saddino (183491) on Thursday December 23 2004, @05:40PM (#11172521)
    As evidenced by this image [yumahouse.com].

  • It happened to me too (Score:5, Funny)

    by Magickcat (768797) * on Thursday December 23 2004, @05:44PM (#11172550)
    A similar phenomena used to occur in my room as a teenager. Perhaps the two occurances are somehow connected.

  • dust devils? (Score:4, Interesting)

    by jokach (462761) on Thursday December 23 2004, @05:46PM (#11172563) Homepage
    The article states:
    And the researchers suspect the shape of the crater may encourage the development of dust devils or other wind patterns that could help scrub the panels.

    The tornado like winds that can be caused by dust devils is something that was discussed by NASA back in April and surely seems like the real answer:

    http://www.space.com/scienceastronomy/dust_devils_ 040420.html [space.com]

    I'm not sure why they think its such a mystery now ...

  • Anyone considered this... (Score:3, Insightful)

    by jbwolfe (241413) on Thursday December 23 2004, @05:49PM (#11172588) Homepage
    Static charge?

  • watt-hours per day (Score:3, Informative)

    by aberson (461047) on Thursday December 23 2004, @06:06PM (#11172723) Homepage
    seems a little redundant

    power * time / time = power

    900 Watts * hours / day * (1 day / 24 hours) = 37.5 Watts.

    Why not just say that to start?
        • Except the Watt *is* an SI unit (the standard SI unit for power, representing 1 J/s). The equivalent Imperial unit would be horsepower, or lbf/s. Further, the joule being a unit of energy, it has nothing to do with this discussion.

          I may be an American, but at least I understand the difference between power and energy.

  • second time this happens in one week (Score:4, Funny)

    by alonsoac (180192) on Thursday December 23 2004, @10:39PM (#11174134) Homepage Journal
    what are the odds?

  • They keep passing checkpoints (Score:5, Funny)

    by iabervon (1971) on Thursday December 23 2004, @11:34PM (#11174430) Homepage Journal
    As anyone who's played a racing car game in the past twenty years can tell you, when you pass a checkpoint, you get more time. As long as they keep completing new areas, they'll keep getting bonuses. On the other hand, if the Spirit team doesn't get moving, they're going to have to put in another quarter pretty soon.

    • Re:Wind maybe? (Score:5, Interesting)

      by Control Group (105494) on Thursday December 23 2004, @05:13PM (#11172265) Homepage
      The reason wind isn't the obvious answer it seems like is that the Martian atmosphere is so thin. I remember seeing (on Discovery HD, IIRC) a wind tunnel simulation NASA was doing to study dust devils on Mars. They set up the chamber at Martian atmospheric pressure, then cranked up a fan to blow some insanely high wind speed. The fine dust on the floor didn't even budge; there just wasn't enough air to make anything happen.

      The only way they were able to replicate the observed dust devil effects was to toss larger pebbles into the chamber, kicking the dust up into the wind.

      Anyway, the point is that wind is still the most probable cause, but it's not quite the obvious slam-dunk that it superficially seems.

      • Dude, if the air pressure is TOO LOW to blow the dust around, then how DID THE DAMN DUST get ONTO THE panels in the first PLACE!?!?!?!

        You cant say fact A)
        "The wind is not enough to blow the dust off the panels"

        and yet say B)
        "The panels got dusty because of wind blow dust around the planet"

        So which is it?

        But we do know mars gets dusty as wild storms do happen, but we havent seen that in any camera footage this year.

        • It's actually possible (for A and B to both be true) if the coefficient of static friction is lower for dust-dust contact than it is for dust-panel contact. In this case, the force required to break dust-dust stiction could be lower than wind forces, allowing the wind to kick the dust into the air, while the wind force could in turn be lower than dust-panel stiction, preventing the wind from clearing the panel.

          I have no idea if that's how it is, I just like saying stiction.
      • They set up the chamber at Martian atmospheric pressure, then cranked up a fan to blow some insanely high wind speed. The fine dust on the floor didn't even budge; there just wasn't enough air to make anything happen.

        Did they decrease the gravity also? Of course not. That's a huge factor right there. We have more than double the gravity of Mars.

    • would wind work (Score:4, Informative)

      by grahamsz (150076) on Thursday December 23 2004, @05:14PM (#11172276) Homepage Journal
      We had gusts up to 98mph earlier this week and my car looks as dirty as ever

    • Maybe.... You didn't read the article did you?

      "At the time, the team speculated that wind may have swept the dust off the panels or frost may have caused it to clump, exposing more of the panels. ..."

    • Re:hmmm... (Score:4, Informative)

      by Moridineas (213502) on Thursday December 23 2004, @05:24PM (#11172381) Journal
      Jeez, RTFA :-p That's exactly what they suggest.

    • Re:hmmm... (Score:5, Funny)

      by Walt Dismal (534799) on Thursday December 23 2004, @06:21PM (#11172838)
      Martian gravity is lower than Earth's, and dust should be lighter and hence easier to blow off. Or shake off - couldn't NASA have built in some way to have the vehicle shake itself like a dog? Or at least jerk forward, stop, jerk backwards. At which point the Martians would groan and wait for the probe to start spouting rap lyrics.

      • Re:hmmm... (Score:5, Insightful)

        by cmowire (254489) on Thursday December 23 2004, @05:34PM (#11172470) Homepage
        No, it's more the case that the cost, primarily in weight, of adding the required fan, wiper, or other cleaning system outweighs the value added with more scientific instruments. And given that the panels are relatively fragile (remember, every gram of mass has a dollar amount attatched to it) you'd need to be awfully careful -- wipers are out.

        Also, it's something else that can fail. Sure, it sounds like a good idea, but if you ruin the solar panels halfway into the base mission because it doesn't work, people start looking really dumb. Or if the shape of grains of martian soil is not quite the same as earth soil and it ends up not working. Or there's something else that might fail, you leave a backup for it out, and then look really stupid when that part fails and you've still got plenty of solar energy.

        The biggest problem, of course, is that the designers of the probe are hamstrung by rather unreasonable launch costs that are showing little signs of getting better and are prevented by vast armies of rather stupid anti-nuclear-power whackos from using a 5 year power source. Oh yeah, and most of the NASA budget is reserved for a space shuttle that is far too expensive and has not been able to be retired and replaced due to a variety of issues.

        But, in general, it's much better to get a different assortment of tools on a different probe in a completely different location every 2 years, with a chance to have design improvements, instead of having two massive probes that last for 5 years and can only be launched every 10 years.

        • Re:hmmm... (Score:3, Interesting)

          by Lumpy (12016)
          then why do they not take a cue from NASCAR and Motocross and have thin mylar tear offs on the panels? that technology has existed cince 1980.

          one on each would ass less than 1/2 gram of weight and using one of the motors that already exists for folding the panels out to perform the tear off would solve the motor problem.

          There really is no excuse except maybe that the materials available for the thin tear offs may reduce the output way too much or might react badly with the higher UV index there and yell
      • Sheesh.

        The engineers decided not to build something to shake off the solar panels, because that would make the darn thing heavier -- which woule mean they would have had to leave something else off.

        Politics had nothing to do with it.

      • Re:hmmm... (Score:5, Interesting)

        by Jester99 (23135) on Thursday December 23 2004, @05:49PM (#11172585) Homepage
        You would think they would have built a wiper to sweap the dust off, or maybe some high pressure air hose or fan. Or thy could have added an ability to vibrate the dust off.

        I got to ask a NASA engineer about this once in person.

        He said they considered it. But then you have to remember that each of these things has moving parts, which are prone to getting dust in them and clogging, or breaking, or whatever. If you wanted, you could also have multiple layers of solar panels and when one got too dusty, it could "molt" and then the fresh panel would be exposed. They've thought of each of these things.

        The problem is that they all add complexity and weight. When you're trying to hurtle something at a planet and have it touch down for landing, making the damn thing bulkier doesn't exactly add to reliability.

        If your robot vibrates, then that could loosen screws and the whole thing could rattle itself into a pile of scrap metal.

        If your robot blows itself off with an air hose, then you need to have a filter system so you know you're not blowing dusty air on it. But filters get clogged, so eventually the hose system would stop working, and the panels would get dusty.

        If your robot molts panels, you then need to add extra motors to lift off a given layer. But these are heavy, and could break. Heavier = more power draw to move around. So if the motors malfunctioned, it wouldn't have gone as far as it would've if it only had a single layer of panels -- meaning you'd get less exploring done.

        Wiper motors ... same problem.

        Nothing political about it.

        • Re:hmmm... (Score:5, Interesting)

          by cot (87677) on Thursday December 23 2004, @06:01PM (#11172675)
          What about several layers of thin clear plastic that's tensioned?

          You have each layer held down with tabs,and release them one by one as the cells accumulate dust. The released plastic curls up at one end of the cells when released.

          You could probably do this at least several times.

          • Re:hmmm... (Score:5, Informative)

            by QuantumFTL (197300) * <<justin.wick> <at> <gmail.com>> on Friday December 24 2004, @02:50AM (#11175199) Homepage
            What about several layers of thin clear plastic that's tensioned? You have each layer held down with tabs,and release them one by one as the cells accumulate dust. The released plastic curls up at one end of the cells when released.

            I work for Steve Squyres (the Principle Investigator) and he said that they considered this option as well, and it was prone to failure.

            Looks like they made the right call after all!

            Cheers,
            Justin
    • Blind luck had no part in it. If you would have actually bothered to learn anything about the Rover project before back seat quarterbacking you would have quickly realized why they didn't build in wipers or some other mechanism.

      However, since you didn't, I'll summarize in brief:

      wipers--would increase weight and electrical requirements of the rovers, thereby decreasing lifespan. Also, the wipers themselves would most likely end up scratching the solar panels or embedding detritus into them, thus decreasing

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