In the last weeks, you can see again high dust levels on the sundial (perhaps comparable to pre-storm levels) and also lot of dirt/residuals on solar panels, clearly visible in Sol1355/58 self portraits!

Was the dust storm so violent to bring these smal pieces of rocks over Spirit?

Waaw, this rover needs another dust clearing wind

My, my..... I am begining towonder if Lady Luck is going to smile on Spirit this time

We had better cross our fingers because with all this dust......u can never tell.

Oooohh! Feelthy peectures! Latest MI s
This looks positively yucky. At what point do we start to think about whether running the RAT brush across it would do more good than harm?
If the choice is scratched solar panels or the Big Sleep, do we dare? How hard is the panel surface?

The RAT would be able to reach perhaps 3 cells out of the hundreds on the array, so it would achieve nothing if it were even a sensible thing to do. Which it really isn't. You could end up expending quite a few Whrs on the operation itself, with the very best result being perhaps a 2% power increase, and the worst result being a power decrease. Most likely, you would end up with three scratched cells, a damaged RAT brush, no more power, and an entirely wasted effort.

Doug

Well... we're at a 30-degree angle. How difficult would it be to use the IDD to "tap" the rover deck a few times? Maybe get the larger clumps to fall off?

No brushing, just a few taps...

-the other Doug

If not, next spring maybe they can "shake, rattle and roll".

Has anyone determined whether the dust is just being loosely deposited on the MERs, or if it's adhering electrostatically as well? I suspect the former since the cleaning events to date would have had to have been extremely energetic to work, but this is a good-to-know thing for future missions.

Well - bad analogy time. Go up to your coffee table. Now touch tap it, with a motion of about 5mm/sec in one corner. Does any of the dust come off?

Can the IDD make mechanical connection with the deck? How about bringing the IDD into mechanical contact with the deck then running the RAT a bit. I would think that would produce at least a bit of vibration.

Ooooh, derf, Like it, like it!
Worth trying. With the RAT ground down, it could well be out of balance.
Just rest the IDD arm on the panel edge and gun it!

Thing is, though, even if this vibration is enough to shake the dust loose, where is it going to go? What we really need is a transverse force--wind--to sweep this stuff off of Spirit.

Well -- if there was flour on it, not dust, and it was close to the flour's natural angle of repose, and if I kept my coffee table at a 30 degree angle, I could answer the question... *smile*...

I'm mostly thinking that, even with a relatively slow, soft impact, even a small vibration might shift rock/salt dust if it's near the dust's natural angle of repose. Of course, we've likely gotten more of a jolt from descending down this slope than we could generate with the IDD.

I will point out that you don't see a lot of dust collected on 30-degree slopes of exposed rocks in the area, and the only things around to clean them off are winds and seismic shocks. One might hope that a combination of this tilt and whatever natural vibrations plus winds might tend to clean Spirit off as time goes on, here.

Still, I think we need to generate some way to shake these things so the dust can shake off...

-the other Doug

Many years ago, I recall someone asking why the MERs wouldn't carry compressed air (I'd favor compressed CO2) bottles & spray fixtures to blow off the solar panels. Didn't seem worth the mass penalty at the time considering the optimal 90-day mission duration, but given the MERs' longevity I'd definitely think about adding such a system for any future solar-powered rovers...

grumble...
What Spirit needs to do is find a nice low hanging bush and sidle up under the branches and bear-rub the dust off.
<dream on>