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