QUOTE (Jeff7 @ Oct 15 2005, 05:59 PM)
6 years? That'd be crazy. I can see it on its last legs, two wheels still working, just slowly dragging it along until they overheat or burn out. Stationary observation time then. How long might the main mast's motors last?

25% chance of lasting 6 years? Interesting thought. Spirit's current power levels back that up though - it looks like we're not going to get any major dust storms this year so dust deposition rates this winter will be lower than last year (when there was a storm, just before the MER's landed) and power should be good at least until the onset of the winter after next. The odds of a storm seem to be between 20 and 30% for any Martian year so based on that 25% odds on lasting 6 years is fair enough.
That's just what the panels can generate though. I don't think the wear rates on the other components look so good.
The batteries were only tested to around 300 charge cycles (I think) so they are way out into uncharted territory already. They probably are good enough for 1000 cycles maybe even 1500 but I can't see them lasting for >10x their design. These are Li-Ion batteries, they are very good ones but the way they degrade measurably after every single charge cycle. Possibly the "deep sleep" operating mode allows the rovers to function with severely reduced batteries but no-one has made it clear yet if that's the case. Hopefully it is.
Keeping the wheels turning and the IDD moving for 6 years seems improbable to me. We've already seen wheel problems and they are after all pure mechanical components that are exposed to a severe environment.
But I'm very glad to see that someone in the know, so to speak, is prepared to say that there is such a high possibility of enough things continuing to work.