You'd still have the same problem though: how do you keep a motor lubricated in the partial pressure of a pretty good vacuum? How do you stop the duster's brushes falling out or wearing out?
Not saying it's not possible, but if you consider things like reaction wheel failures, there's a lot of "might last a long time, might die in a year or two" problems in any motor in space.
There are plenty of other motors on the landers, presumably the rovers haven't been telekinesing merrily over the marscape. The brushes would be a far lower duty-cycle item.
Depending on the brush design: something sufficient to clear the panels periodically (say, based on noted solar degradation and/or self-inspection photography) might work. Clearly, incidental wind has proven sufficient.
And there's a lot of engineering work on Earth which could go into testing out the design. As I said: it's just curious that this seems to have been left to chance. Though nobody really expected the rovers to run as long as they have.
> There are plenty of other motors on the landers, presumably the rovers haven't been telekinesing merrily over the marscape. The brushes would be a far lower duty-cycle item.
But far more exposed, though. If not the motors themselves, then the mechanics of the wiper arm.
More so than camera servos or other arms on the probes?
Again: while high-reliability, low-pressure lubrication is a challenge, it's clearly not an insurmountable one. Providing a means to ensure your only source of energy remains viable would be useful. Failure of the dusting system of itself wouldn't result in a mission failure. Success of it could prolong it, and/or allow for smaller collectors (as I recall the solar panels were oversized to allow for possible dust accumulation).
I'm thinking of some sort of rotary duster which might pass horizontally above the panels. Less a windshield wiper design than a dual-arm rocker.
Not saying it's not possible, but if you consider things like reaction wheel failures, there's a lot of "might last a long time, might die in a year or two" problems in any motor in space.