Spirit Explores the Columbia Hills.

Pity that NASA didn´t try find a way to clean dust from the
solar panels; I think that I read somewhere that this was at
least brought up but nothing came of it - probably they thought
the rovers would be dead before dust accumulation on the solar
panels would become a problem.

What the MER rovers show is that you could really have Mars
rovers that could work for several years on Mars and that
they wouldn´t necessarily have to be nuclear-powered like
the 2009 rover.