Could brush have extended life of multi million dollar mars rovers?

I read about how well the rovers are doing and how the solar panels collecting dust appears to be the biggest rover killer. Why on earth was a brush not installed on the robotic arm that could have been used to seriously extend the life of these massively expensive rovers?

www.space.com...

Sad but a 5 dollar brush coulda trippled multimillion dollar mission.

Maybe Im missing something but I think it was a huge oversight on an otherwise awesome mission not to include some way to clean those solar panels off. A simple brush attachment next to the high tech rat might have tripled the life span of the Rovers no?

I remember watching NASA TV and this question was asked. The answer was something to the effect that the particles that acumilate are tiny "dust" and it would take something like a liquid and a squeegie(sp?) to clean them, and even then not completely. The cost of inventing and creating a devise that would work (liquid would freeze instantly so this idea would not work.) would be too costly and time consuming. This mission was to perform a few simple tasks, setting up further missions to do more. Anyway, the rovers are going just fine and they are way over the targeted lifespan projections and may go on for more than anyone would have ever expected. By the way, they have really done what they went there for, and all they will continue to find with the instruments they have will be more of the same so really prolionging their life wouldn't benifit anyone much.

The rovers were only supposed to go 90 days to meet the requirements. The dust is very fine, like corn starch or diatenacious earth, not like sand. The dust there also appears to develop a static charge. They are looking at putting the rovers into hibernation for the winter and see if they can revive them next summer.