Spirit cleaner? Options

[centsworth_II]

But fortunately getting to a steeper slope may not mean having to drive uphill.

Right!

[helvick]

The best they could do for the day that insolation is lowest ( around Ls 95 ) is to tilt to ~34.6deg facing due north , that would result in about 31% more power than a horizontal panel on the same sol.

The initial tilt angle at Low Ridge was 10.8deg which gave them about 15.7% more power than a horizontal panel on that day.

34 degrees is probably way to dangerous but a 20deg slope should be possible and that would yield a 25% increase in power.

The exact improvement varies over time as the suns declination changes - the above numbers are really only good for the weeks around mid winter.

[centsworth_II]

... the above numbers are really only good for the weeks around mid winter.

That's a good time to have the maximum improvement!

[brellis]

The subject of tilt begs the question, why don't the panels pivot to track the sun? I'd never thought about that. In the design process, if there's already a motor to unfurl the panels upon landing, couldn't that same motor rotate the panels and shake off dust in the process? I'm sure they thought about it, but I'm curious about the pros and cons.

Apologies if this question was addressed in an earlier thread. I'm a newbie, so I'm just learning how to read

[djellison]

The dust probably wouldn't come off if you tilted the panels - it's fairly clingy. The motors only work one way ( I think) - I think they lock in place on deployment. And of course, what do you do if you end up with an array stuck up at an angle.

Doug

[Tom Tamlyn]

Further to the same point, the deployment motors were only expected to work once. Designing and building them so that they would have continued to operate reliably in the Martian environment throughout the mission would have been something else.

TTT

[brellis]

Further to the same point, the deployment motors were only expected to work once. Designing and building them so that they would have continued to operate reliably in the Martian environment throughout the mission would have been something else.

TTT

Ahh, that's the part I wasn't thinking about -- that, and using the motor continuously probably drains more power than you'd gain from tracking the sun. Then, at some unknown point the motor dies, and what if it freezes at a sunrise or sunset position. Well, I'm just glad I wasn't making that particular decision during the design process

[alan]

Cleaned Again: Spirit Self Portrait

http://marswatch.astro.cornell.edu/pancam_...ent/adeck3.html

[Nix]

woaw.. she looks good!

Nico

[Shaka]

But she could look better! Come on you devils/angels! You missed a few spots.

[kenny]

I never appreciated how variable the dust covering could be from panel to panel until I saw that pan, alan....

[Guest_Oersted_*]

Looks like the cleaning has been more efficient in the center panels (or maybe they were cleaner to begin with?). If it is turbulence that helps clean the panels, maybe it would be a good idea to have "turbulence provokers" on the sun panels of future rovers? Maybe wispy stalks standing up from the rover deck, thin enough to not cast shadows but still churning up the air. Just brainstorming here...

[CosmicRocker]

Being from sol 1229, I think that self portrait was after the first cleaning of this season. The second cleaning, which boosted Spirit's output to 50 W-hrs greater than Opportunity, was on sol 1233. We have gotten only a few navcam images of parts of the deck since then, so it is difficult to see what may have changed.

[fredk]

From the latest Planetary Society report, this description of the sol 1224 cleaning event:

"This [dust-cleaning event] was interesting, different from cleaning events we've had in the past," Squyres said... . "In the past, we've had cleaning events that took place when we were on a summit or a ridgecrest and in the past they have sometimes occurred at night. The rover will shut down in the afternoon with dirty solar panels and wake up in the morning with clean solar panels and we have no idea exactly when it happened. In this particular instance, the rover was awake and busy and active when the event happened so we can pinpoint the timing of it. It happened at 1:20 pm in the afternoon local solar time. Of course, we are now down on a low spot, not up on a ridgecrest of anything. So our speculation –- this is pure speculation at this point – but our speculation is that we took a direct hit from a dust devil. We don't know that. But we are in place where dust devils happen and it's prime time for dust devil activity, the time of day when dust devils seem to be most active."

[Shaka]

Yes, only a devil would tidy up so haphazardly.