Mars Winds Clean Spirit's Solar Panels Again 269
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.'"
Next time . . . (Score:5, Funny)
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Re:Next time . . . (Score:5, Informative)
Re:Next time . . . (Score:5, 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.
Re:Next time . . . (Score:5, Interesting)
Re:Next time . . . (Score:5, 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".
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NASA still decided not to put on a brush, wiper, or (sorry but lol) air compressor.
There is a thin atmosphere on Mars. It may be enough for a very small air compressor to build up enough pressure to simply blow the dust particles off the panel. We're not talking about moving anything large. Just a small burst to clear the panel. The problem with a brush or wiper is that the moving parts would be exposed to the dust which would most likely result in them breaking. If all that was exposed was a nozzle w
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Thank you for responding to the first half of my post with a simplified version of the second half of my post. That was very informative.
Re:Next time . . . (Score:5, Funny)
now WHO gave these two too much candy??
Re:Next time . . . (Score:5, 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.)
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As well as hope that you aren't sandblasting your panels with it when the barrel gets clogged.
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So you think a tiny air nozzle would sandblast the panels compared to the dust storms on Mars?
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Or here's an idea- mount the solar panels on a slant.
Re:Next time . . . (Score:4, Informative)
Screw Next time . . . (Score:5, Insightful)
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
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!
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18 minutes. Sheesh.
Re:Next time . . . (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!
Re:Next time . . . (Score:4, Insightful)
I don't see how the benefits are minor, considering how much press and excitement is triggered each time the winds clean the dust off. Also considering the massive longevity to the mission that more runtime creates. More life = more science, and since the whole point of these missions is "science", that's more bang for your buck.
It's not easy to get stuff to Mars, and there are only occasional windows of opportunity. Best to get as much as you can out of the missions you DO send.
I don't see how there can be much "static cling" if just wind can dust them off.
Re:Next time . . . (Score:4, Insightful)
Re:Next time . . . (Score:4, Interesting)
They never expected the mission to go this long. Things were calculated at a success level of 90 days.
Indeed because of the success of these two rovers the next missions will be similar. The next mission may or may not benefit as often it is the failures that teach better than the successes.
It may be that the rover happened to have landed in a particularly windy part of the planet, or a part with a particularly un-clingy(love my technical wording!) local dust conditions and the next mission may be different and fail even if the exact same equipment is used.
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Phoenix lasted as planned (Score:3, Informative)
Re:Next time . . . (Score:5, 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.
Re:Next time . . . (Score:5, Funny)
Two astronauts, one faceplate?
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Just reverse the polarity. In start trek it fixes everything.
Re:Next time . . . (Score:4, Funny)
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.
Okay, so they needed to include a windshield wiper AND a bottle of 409.
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They could have coated the panels with a layer of Snuggle :)
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Ok... how abut a cleaning fan or a blower mechanism of some sort? If you can prolong a mission for as long as this one has been perhaps such equipment would be worth the effort? Especially since the Mars winds seem to have proven the concept.
They may have discovered that an effective fan would require more power than was available. Then there's the complexity and all. Not to mention which, it's a fairly reasonable approach to simply evaluate how frequently such winds occur and decide to rely upon them.
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Re:Next time . . . (Score:5, 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.
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First of all the dust is not only super clingy, it may also be abrasive. Physically removing the dust via brush may scratch surfaces.
Second, if the dust isn't abrasive what materials would the brushes and plastic film be made of. Remember they have to be softer the the panels or they'll scratch them. Typically on earth they are made of a synthetic like nylon and HDPE. Would such materials survive the harsh environment of Mars? The extreme shift of cold and hot of Mars days would make most soft materia
Squeegee kid (Score:3, Funny)
Re:Squeegee kid (Score:5, Funny)
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.
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>>>The Martian curator bots periodically dust the solar panels
I figured the bots performed an upgrade, such that the panels are just as dirty as before, but now they have been upgraded to more-efficient Martian red-dust-based panels.
Another possibility is that the panels have been infected by microbes that scrubbed the surface clean, thereby boosting power levels.
Or it could just be wind.
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Re:Squeegee kid (Score:4, Funny)
How much longer? (Score:3, Interesting)
How much longer can this thing go? I mean, it was "designed" to only go a few months, and we are years beyond that. Anyone have a pool on when it will really stop working?
Re:How much longer? (Score:4, Informative)
Re:How much longer? (Score:4, Insightful)
Rule 1 of engineering: Underestimate your estimates.
The thing was designed to run for years. However they gave it a 90 Day limit to save their butts if it breaks in 85 days. as well the mission spec was for 90 days, so they made sure it would last that 90 days as much as possible. It is not like you going to put up a million dollar probe and skimp on parts. You are going to make it as robust as possible as estimating 90 days of operation in the unknown is quite hard.
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Anyone have a pool on when it will really stop working?
The way this things are going, that's something best handled here [longbets.org].
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How much longer can this thing go? I mean, it was "designed" to only go a few months, and we are years beyond that. Anyone have a pool on when it will really stop working?
They thought the dust would clog the solar panels so that it would be mechanically intact but powerless in three months. Using that to figure out how long it'll last now is like trying to figure out how long a laptop will last on AC power based on how long you thought it'd last on battery power. The short answer is until something breaks, it's mechanical and hasn't been to service for five years but trying to say exactly when is like trying to predict when you'll need a tow truck for your car. Even if it's
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Windows 7 will be dead before the rovers.
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I think there should be a nobel of engineering or something similar, given to whomever designed that rover.
It /never/ happens in real life that you can get away with designing a piece of equipment that outlasts it's fail-by-date by so much. In most companies nowayday, these guys would be in trouble !
It sort of ought to be encouraged somehow...
list of broken parts (Score:2)
Opprtunity's arm wont completely contract, so they drive it loose instead of docked.
Both of the RAT grinders have warn out, so they cannot drill millimeters into rock like they used to.
The camera lenses are dusty. Sometime the wind cleans them up a bit.
I am sure there are others.
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Published estimates were likely wrong on purpose
I agree with you there.
to give them the opportunity for more media coverage and subsequently budget opportunities
If this [discovermagazine.com] is what you meant by that then I agree with you there ;)
Re:How much longer? (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."
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Re:How much longer? (Score:4, Interesting)
I don't know what confidence threshold NASA uses, maybe more than 95%. So the 5 years these lasted is lucky, but not so completely off the charts as it might seem.
Re:How much longer? (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)
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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.
My understanding is that they estimated a 90 day lifespan because that's how long they calculated it would take before too much dust accumulated on the solar panels for the rovers to function.
They didn't know (might have suspected, but certainly did not know) that the Mart
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Published estimates were likely wrong on purpose from the start to give them the opportunity for more media coverage and subsequently budget opportunities.
Bzzt. Wrong. First of all, what you're quoting (90 days) never was an estimated lifespan. If the estimated lifespan of a craft was 90 days, that would mean there's a substantial chance you'll only get 60 days out of it, or 120 for that matter. 90 days was never the expected lifespan. 90 days was the promised minimum lifespan. They were very certain it would last at least 90 days. If you think about that a minute, that means they estimated it would probably last much longer than that, or else they cou
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That's fairly likely -- conservative estimates are wise estimates. As they say, "Under-promise and over-deliver". But a multi-year estimate may have been a bit overly ambitious, after Pathfinder [wikipedia.org] only lasted three months (which was better than the 1-4 week estimate they gave at the time).
Of course, on the other hand, both V
Winds of Change... (Score:2)
Okay...why haven't we? (Score:2)
We've proved that the budget rover designs have been the most successful designs we've sent to another planet.
They've been resourceful and far roaming...so why haven't we expanded on the design.
I think we should package up some new rovers. Slightly larger with additional equipment. With one additional design feature. A means to self-clean it's own solar panel.
This way the unit could theoretically operate for near perpetuity.
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Next up is the Mars Science Laboratory. Bigger, better, and nuclear powered with radioisotope thermoelectric generators.
P.S. cleaning a solar panel is hard [newscientist.com]. Did you really think the designers overlooked it?
Boy... (Score:2)
Well at least this mission taught us one thing... (Score:2, Funny)
... there are no homeless people on Mars.
the next lander is nuclear powered (Score:5, Informative)
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The poster didn't say that those things were the new technologies of the new rover.
The fanciest, and most problematic, is a laser system that cooks rocks several feet away so that a spectrograph can analyze the chemical signature of the plasma from the heated area remotely. Pretty cool if it works. This would allow the rover to inspect several rocks without having to navigate to each and every one. A major increase in productivity if it works.
But it does look like they are putting a lot of big eggs in one b
Rover Driver Blog (Score:4, Interesting)
Anyone interested in the Mars Exploration Rovers' mission should check out Mars And Me [blogspot.com], 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.
Re:Include cleaners next time? (Score:5, 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.
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How do you get the dust off your hand afterward (so that it'll be clean for next time)?
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Easy... brush it off on your shirt.
Re:Include cleaners next time? (Score:5, Informative)
This comes up every time the rovers are mentioned. Here is a detailed explanation [newscientist.com] why there are no wipers, or any other cleaning device, on the rovers.
Re:Include cleaners next time? (Score:5, 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.
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The next rover uses an RTG for power, so there won't be a need for wipers or any other such thing:
Mars Science Lab [nasa.gov]
I guess the radiator portion of the RTG could get enough dust on it to cut down on its effectiveness, but Mars in general is still pretty cold, so I doubt there is nearly as big of an issue as dust on solar panels.
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"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."
180wh for survival. They were generating 210wh. Now they're getting 240wh.
210wh-180wg=30wh discretionary.
240wh-180wh=60wh new discretionary.
No wonder you're not a rocket scienti
Calm Down (Score:2)
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They are not counting the overhead to keep the thing alive. They've doubled the amount of power available for science etc.
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A 30W bulb? Wow. The room I'm in now is lit by a single 18W lamp and that's more than adequate. I realise that American homes tend to be more spacious, but seriously - 30W? How large are your rooms?
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Re:Amazing (Score:4, Funny)
My computer uses nearly that much power under full load, and it doesn't even have to move!
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This thing is cruising around mars...
Not as much as you think. [wikipedia.org]
"As of sol 1736 (November 20, 2008), Spirit's total odometry was 7,529 metres (4.68 mi)."
Re:Amazing (Score:5, Informative)
Re:Amazing (Score:5, 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.
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240 watt-hours, not 240 watts. (Unless you only want to operate for a single hour!) For comparison, 240WH is roughly the energy in a dozen alkaline "D" cell batteries. If the probe is to operate 24 hours* on that power, that's only ten watts on average.
=Smidge=
(*Earth hours, of course)
Only on Slashdot! (Score:5, Informative)
Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.
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Re:Only on Slashdot! (Score:4, Informative)
For redundancy. If the Joules run out, it can still run off the watt-hours, and vice versa.
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Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.
Actually, "Only on slashdot will some people actually notice that the poster used the wrong units" might be more like it. Whether or not the moderators notice, on slashdot you know *someone* will alert you to your mistakes, whether it's having the wrong units, wrong spelling, or wrong point of view.
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On exactly how many sites can a post be modded "+3 Interesting"?
More amazing is that it keeps going (Score:3, Funny)
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because I don't want to pay $456,784 for a lightbulb :)
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why can't our terrestrial equipment be this efficient?
It can be, it's just too expensive or annoying. My PC has all these high tech power saving features. I've disabled most of them because they're annoying.
Amazing affects. (Score:2)
why can't our terrestrial equipment be this efficient?
It can be, it's just too expensive or annoying. My PC has all these high tech power saving features. I've disabled most of them because they're annoying.
Apparently the feature that turned off the user was left on.
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You do realize that the sun doesn't shine the entire 24 hours and 39 minutes in each day?
So you don't get a constant power over the day.
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The next one will be; the Mars Science Laboratory will use radioisotope thermoelectric generators.
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