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Mars Winds Clean Spirit's Solar Panels Again

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.'"

24 of 269 comments (clear)

  1. Next time . . . by OhHellWithIt · · Score: 5, Funny

    . . . don't forget to pack the broom.

    --
    "Who controls the past controls the future. Who controls the present controls the past." -- George Orwell
    1. Re:Next time . . . by Tubal-Cain · · Score: 5, Informative

      They decided that a windshield wiper didn't have a good benefit/cost (in both money and weight) ratio. Especially for a 90-day mission. I understand that the best they could get the wipers to do was smear the dust around (something about static cling keeping it from coming off), so it wasn't going to do much good, anyways.

    2. Re:Next time . . . by SilverJets · · Score: 4, Interesting

      So what about an air cannon or something? Small pump to take in Martian air, build up pressure, and a small nozzle directed at the panel to blow the dust off.

      I know, every ounce of weight and every bit of energy has to be calculated and accounted for. But they had to know that dust would accumulate on the panels and should have accounted for that with some type of design.

    3. Re:Next time . . . by solafide · · Score: 4, Interesting

      90 days.

    4. Re:Next time . . . by blueg3 · · Score: 4, Interesting

      They did know. They also knew that all the possible solutions had significant costs and/or chance of failure. (As far as the air cannon, Mars air is very thin, so you have to have a quite significant wind to move the dust.)

    5. Re:Next time . . . by dpilot · · Score: 4, Interesting

      Arthur C Clarke wrote a nifty short story that encapsulated some of this. I can't even remember the title, so spoilers are uselss, and I'll just give the gist.

      Two astronauts were exploring on the moon, and the wandered into a dust bowl. They got a little dust on their faceplates, and made the mistake of wiping them. The generated static transferred all of the dust to the faceplate, and they were still deep enough in the dust that it attracted more. So even though the dust bowl is shallow enough to simply walk out, they can't see, and so far they haven't found anything they could rub the faceplate with where the static electricity would go the other way, taking the dust off.

      Solution:

      They rubbed faceplates together. One faceplate takes the charge that takes the dust, the other cleans. Then the astronaut with the clean faceplate can see the way to the buggy, leading the other.

      --
      The living have better things to do than to continue hating the dead.
    6. Re:Next time . . . by UnknowingFool · · Score: 5, Funny

      Your post advocates a

      (X) technical ( ) legislative ( ) market-based ( ) vigilante

      approach to Rover problems. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)

      (X) It requires too much power
      ( ) It may make situation worse
      ( ) It doesn't solve the problem
      (X) It works here on Earth but not on Mars
      (X) It will work for two weeks and then it might get stuck
      (X) It does not account for the climate of Mars
      (X) Marvin the Martian will not put up with it

      Specifically, your plan fails to account for

      (X) Weight limitations on mission payload
      (X) Space limitations on mission payload
      (X) Extreme cold of Mars
      (X) Atmosphere of Mars
      ( ) Difference between Mars gravity and Earth gravity
      ( ) Materials don't exist yet
      (X) Survivability of materials on Mars
      ( ) Distance between Mars and Earth
      ( ) NASA bureaucacy
      (X) Technically illiterate politicians
      (X) Marvin the Martian
      (X) Democrats
      (X) Republicans
      (X) Ralph Nader

      and the following objections may also apply:

      (X) Ideas similar to yours are easy to come up with, yet none have ever been shown practical
      (X) Solution is beyond mission scope
      ( ) Solution solves the wrong problem
      ( ) Only delays the inevitable
      ( ) Cost limitations
      (X) Requires redesign
      (X) Scientific instruments may have to be excluded
      ( ) Feel-good measures do nothing to solve the problem

      Furthermore, this is what I think about you:

      (X) Sorry dude, but I don't think it would work.
      ( ) This is a stupid idea, and you're a stupid person for suggesting it.
      ( ) Nice try, assh0le! I'm going to find out where you live and burn your house down!

      --
      Well, there's spam egg sausage and spam, that's not got much spam in it.
    7. Re:Next time . . . by Chris+Burke · · Score: 4, Informative

      90 days.

      Which is how long they estimated it would take for the rovers' solar panels to be covered in too much dust for the rover to function. Dust is why the mission was scoped at 90 days. They didn't know that the Martian wind would be of any use whatsoever in cleaning off the panels.

      Yet even though dust is what was limiting the scope of the mission, NASA still decided not to put on a brush, wiper, or (sorry but lol) air compressor. Given there's enough obvious tradeoffs in mass/space/power use for anything you add, I'll give NASA the benefit of the doubt and assume they actually calculated the tradeoffs and said "not worth it".

      --

      The enemies of Democracy are
    8. Re:Next time . . . by thenickdude · · Score: 5, Funny

      Two astronauts, one faceplate?

    9. Re:Next time . . . by dgatwood · · Score: 4, Interesting

      Actually, it's pretty easy. We've discussed this before every time the subject comes up. Put a continuous roll of clear plastic at one end of the panel and a take-up roll on the other end. Make the plastic travel in a track with brush seals so that nothing can easily get in behind the plastic. Periodically roll the plastic to keep the portion atop the panel clear. When you get to the end of the roll, reverse the direction. You'll have less power that pass, and eventually this won't be practical, but it will work for a really long time. For that matter, you could have a series of brushes along the path of the plastic beyond the panels that would significantly reduce the dust level on the plastic even on the second and subsequent passes. And because it is just a simple motor on a spool, it is about as mechanically trivial as you can get, unlike... say a windshield wiper... and best of all, if you scar the plastic, you're not scarring the panel itself and risking causing a panel failure.

      --

      Check out my sci-fi/humor trilogy at PatriotsBooks.

    10. Re:Next time . . . by apostrophesemicolon · · Score: 5, Funny

      enough kids...

      now WHO gave these two too much candy??

  2. Re:How much longer? by al0ha · · Score: 4, Informative

    Yep - there are pools at JPL and Caltech. Go Beavers!

    --
    Did you ever wake up in the morning, with a Zombie Woof behind your eyes? -- FZ
  3. Re:Squeegee kid by GargamelSpaceman · · Score: 5, Funny
    It was a martian. You see about a billion years ago, the Martian civilization discovered the secret of consiousness. Eventually the robots they created displaced them, and then when the planet's resources were depleted, they left for the stars leaving behind some curators. These curators are not really consious, their robotic creators ensured this so that they would be reliable in their task of preserving their martian heritage, but sometimes they do act in ways that are, almost uncannily lifelike.

    This was the case here. The Martian curator bots find the rovers interesting, or rather, they find their controllers interesting. They periodically dust the solar panels so that they will be able to keep roving. They are curious as to what they are doing, maybe even appreciative that someone has visited to appreciate what they have devoted the past eon to preserving. For them, watching us look is most gratifying. They really ache to communicate with us and show us all the Martian history in their underground vaults, but because of their programming to remain inconspicuous, they can't. Still, they are helpful when they can be and not give themselves away.

    --
    ...
  4. Re:Include cleaners next time? by CompMD · · Score: 4, Informative

    Weight = money. At $10,000 per pound, it would have been a waste of money for a vehicle designed to last only three months.

    If the vehicle were designed to last five years, it might be a different story.

  5. Re:Include cleaners next time? by smooth+wombat · · Score: 4, Informative

    Maybe next time, NASA should include some type of cleaning devices,

    This comes up every time the rovers are mentioned. Here is a detailed explanation why there are no wipers, or any other cleaning device, on the rovers.

    --
    We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
  6. Re:How much longer? by Chabo · · Score: 5, Funny

    And of course, the scene from the TNG episode "Relics":

    "Starship captains are like children. They want everything right now and they want it their way. The secret is to give them what they need, not what they want."

    "I told the Captain I would have this diagnostic done in an hour."
    "And how long will it really take you?"
    "An hour!"
    "Oh, you didn't tell him how long it would really take, did you?"
    "Of course I did."
    "Oh, laddie, you have a lot to learn if you want people to think of you as a miracle worker."

    --
    Convert FLACs to a portable format with FlacSquisher
  7. Re:Amazing by evanbd · · Score: 5, Informative

    Not 240 watts; 240 watt-hours. With 24.6 hours per Martian day, that's about 9.75 watts average consumption.

  8. Re:Amazing by Kjella · · Score: 4, Interesting

    Cruise is something of an exaggeration... they've gone 13 miles in 5 years, put together. The Lunar Rover missions each went longer than both combined in 3-4 hours, at top speed they'd pass the rovers within the first hour. Semi-stationary crawlers is a more accurate description, but of course they've been loaded up with scientific equipment rather than for showing off.

    --
    Live today, because you never know what tomorrow brings
  9. Only on Slashdot! by blind+biker · · Score: 5, Informative

    Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.

    --
    "The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
  10. Re:How much longer? by dlevitan · · Score: 5, Insightful

    NASA probably has a good idea. Published estimates were likely wrong on purpose from the start to give them the opportunity for more media coverage and subsequently budget opportunities.

    Not exactly. Estimates are based on worst case scenarios. What would have been the public's reaction if NASA had said that the rovers would last 1 year but they only lasted 6 months? NASA guidelines require that when something is supposed to last x months/years, then it's engineered such that it will last that long, no matter what. Specifying mission requirements is actually a tricky problem for the scientists on a mission because you want the most possible science that fits within a budget and that will last for as long as you say it will last. And usually the only way to convince NASA that something will last is if you add in backup systems. With new, expensive technology this becomes even harder.

    So yes, the rovers were conservatively estimated to last 3 months. I'm sure the scientists on the mission expected that they would last longer, but 3 months was a good benchmark that provided a good amount of science for a reasonable cost. Everything else has just been icing on the cake (and in this case, a lot of icing). Personally, I think they did a great job and cannot fault them at all.

    (I am a grad student working on a NASA mission and have seen a bit of how this process works)

  11. Re:Include cleaners next time? by NerveGas · · Score: 4, Funny

    How dare you inject a useful, explanatory article into the armchair quarterbacking? I don't know where you think you are, but this is [i]Slashdot[/i], kid. Take that stuff somewhere else.

    --
    Oh, you're not stuck, you're just unable to let go of the onion rings.
  12. the next lander is nuclear powered by peter303 · · Score: 4, Informative

    The Mars Science Lander is two years late and a billion dollars over budget because it has developed lots of new technology. It was supposed to launch during the 2009 optimal planetary configuration, but will have to wait until the 2011 one. The next lander uses a nuclear source and rocket landing instead of airbags. I'm a little fearful all the new stuff may not work as planned. I am also fearful NASA budgetary troubles may still kill it.

  13. Rover Driver Blog by TrekkieTechie · · Score: 4, Interesting

    At night, there's a small red light in the sky. On that light lives four hundred pounds of thinking metal sent from Earth. I tell that metal what to do, and it does it.

    Anyone interested in the Mars Exploration Rovers' mission should check out Mars And Me, the unofficial diary of a Mars rover driver. Scott Maxwell is blogging his daily work at JPL exactly five years later. A very interesting and well-written look at the day-to-day operations of a truly amazing scientific expedition.

  14. Screw Next time . . . by Capt.DrumkenBum · · Score: 5, Insightful

    How about we all stop thinking that we have better ideas than the guys who built these incredible pieces of machinery?
    I mean the designers built two rovers that had to survive a launch from earth, months in deep space, a bouncy landing on another world, and then operate correctly with a 10 minute (Or longer) radio delay.
    That is an incredible accomplishment! Then for it to continue to operate for YEARS! I am in awe of the designers.
    Now here on /. we have a bunch of armchair engineers believing they could do better?
    Do you honestly believe that the same people who built these incredible machines didn't think of a solar panel wiper? A can of compressed air? A fan? A compressor?

    To the designers: If any of you are reading this. My hat is off to you. Well done!

    --
    If I were God, wouldn't I protect my churches from acts of me?