All,
See the Mars Explorer website: http://marsrovers.jpl.nasa.gov/spotl...20_Spirit.html

Dust on the solar panels now limits the energy available to Spirit to about a third of the design level. NASA are seeking good ideas to clear it, short of whistling up a Martian wind storm.

My suggestion - probably unimplementable on Spirit or Opportunity - is to use the mechanism that folded up the panels for flight. Some time on battery power, with the panels folded up, at a more vertical angle, aided by a short drive over stony ground if power permitted, could shake off a lot of dust.

John

That's a really good idea! They should use it!

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Find a big rock and park against it. Done right this may change the airflow over the solar panels enough to allow the wind to pick up a little dust from the panels.

I believe the deployment mechanism locks, so that you couldn't drive it backwards. And even if you could - my TV screen is near vertical...yet the dust doesn't just fall off. Dust removal from arrays is actually a problem that has been solved - using electrostatics and a cunning film that you put over the array which will remove the dust on applying an electrical signal. It wasn't ready ( and the mass, volume, time and money wouldn't have been available even if it were ) for MER.

You need to re-read that website as well, NASA are not ACTUALLY seeking ideas..

"If Mars had an on-line Web site for ads, one of them might say something like this: "Wanted: Gentle space-age dust removal system to clean solar cells without leaving grit behind. Please direct inquiries to NASA."

Also- the page itself is a bit wrong, because despite it saying "Spirit is experiencing the lowest energy levels to date" - it's not. Opportunity experienced power levels that were HALF what Spirit is currently getting during the dust storm last year. Spirit also matched its current levels at the same time.

It's not a good situation, it's not a productive situation, but it's a proven survivable situation.

Doug

And Spirit is actually doing better than they thought it would at this point because the skies are very clear.

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Thanks for the further details.

John

To be honest, I'm surprised and disappointed about the lack of response to this.
All the ingenuity and imagination that posters apply to abtruse cosmological Qs, and you can't think of one - not one! - idea that could help this problem.
I know that NASA aren't reallly asking for ideas, but then they're not asking for your views on......eg the nature of Phobos, either.

John
PS Sorry, Rb had a idea, but I think it was tounge in cheek

Have you searched the forum for the numerous other discussions of dust removal on the MER and other Mars rovers?

Edit: One from a year ago, Mars rover question, had links to several previous.

(Keywords: mars mer rover dust wipers wiper peel removable plastic sheets vibrate shake magnets broom brush brushes robot fans blowers tilt antistatic static)

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Yes, Ronald's idea is sound, as airflow around an irregularly shaped rock can indeed accelerate it while inducing vertical currents, thus magnifying the effect of the wind.

The idea of static is key, too, particularly if combined with the rock idea. Is there any way to alternatively charge the panel's surface positively, getting rid of the positively charged dust, then negatively to get rid of the negatively charged dust?

I would think that simply grounding one side of the power leads to the physical ground might do the trick, if that's at all possible.

If not, would it be possible to beam a half-wave (or diode rectified), tightly focused, and very intense EM signal towards it to charge the panels? It would require a LOT of power, but something might be doable.

(The greenies will hate this next one, but here goes...): Could it be possible to detonate a nuke in a way that generates an EMP without frying ground-based electronics and focus/direct it's energy towards Mars? By the time it arrived, it wouldn't be very powerful, but it might be enough to increase the static field on the panels to charge the dust and create a repelling force.

Alternatively, I know there are portable EMP devices that can take out entire cities like Las Vegas because I saw it in Ocean's 11, so it MUST be true.

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It's already fixed in two ways.

1) Take something other than solar arrays. MSL's MMRTG for example

2) http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2014.pdf - http://marstech.jpl.nasa.gov/content...t=&TaskID=2300 - the electro mechanism I mentioned previously.

No wipers, no rolling plastic, no actuators. Perfect. Problem solved. The only solar powered lander on the cards is Phoenix, and the arrival of 24 hour darkness and a burial under CO2 frost will kill that, not dust. MSL, the only other lander currently approved, is using an MMRTG.

Doug

Thank you, jellison!

As you know, NASA weren't really seeking solutions, and I just thought what an interesting discussion might develop among such ingenious people - but no!

The solution to which you pointed (are you involved with it?) is most ingenious. If it could be, or need to be implemented, I suspect that the significant area of the electrodes would mean that a smaller area of photoelectrics could be fitted/unit area. With 0.7mm electrodes, spaced at 1.5mm, the best spacng found so far, over 45% of the available area is covered by dust electrodes, so the light collecting panel will need to be half as big again for the same output. Would you agree?

John

Nope - at the IAC in 2006, I saw a video of a version that was essentially transparent. I would say it was > 99% transparent with very fine wires triggering the effect. I just can't find those vids on line

D

If the wind does not blow off dust, it is likely that it is at least partially because it is adhering due to an electrostatic charge. This is very common for dust to blow up against something and generate a small electrostatic charge that keeps it sticking to it.

It's very annoying with photographs, plates and slides. A common tool to help is a static eliminator:http://www.orau.org/PTP/collection/c...eliminator.htm


The static eliminator actually has a small amount of a radioistope in it (normally a sealed polonium-210 source, but some industrial ones use Am-241 or something else).

The alpha particles produced ionize the air and the top of the plate or photo and this eliminates the static charge. Once you sweep the photo or printing plate or whatever with the static eliminator the dust won't adhere. Apparently also once used commonly for vinyl records.

The rovers have an alpha particle/X-ray spectrometer on the end of an arm with a small amount of a radioactive material. I don't know if it's mechanically possible but if they could point it at the solar cells it might help remove the dust.

As long as it's a couple inches away I doubt that it would cause any damage. Alphas won't penetrate the outer protective coating of the panels and the solar panels are subject to radiation anyway so they'd be hardend against it to some degree

The IDD can reach only the front two or three cells on the front of the arrays - and has done so, quiet regularly, to do MI imagery of them.

Doug