http://www.planetary.org/news/2007/1231_Ma...ate_Spirit.html

Happy New Year to all

Wow!! That was a good article.

I'm glad the rovers are currently is good health; but I am worried about Spirit. Spirit may be able to survive this winter, but the trend for efficiency of solar cells dropping with each winter indicates that this is the last winter that the rover might survive. That means we have about two more years with Spirit and that is about it.

Opportunity is a different story. It will survive this winter easily and will likely survive several more winters (as long as other systems remain healthy). We may have another 4 to 6 years of rover viability for Opportunity--maybe more. That means we should be able to finish the science at Victoria and be well into the mission out on the plains. Given the health of Opportunity, I think it is appropriate to discuss a possible mission beyond the plain. Can Opportunity make it to another big crater? I always doubted it until recently.

It's not the efficiency that's dropping - that's probably a bad choice of words all round - it's the dust loading. One good cleaning event and we're back to 10-20-30 percent.

And we're not having another 'after victoria' discussion about driving 15km to another crater - there's one already.

Doug

Well, cleaning events do help; but they require a bit of luck. The long term trend that I used includes cleaning events. So although we could get lucky, IMO we cannot count on Spirit making it through another winter beyond this current one. Yet, that still means we might have two years left for science with this particular rover.

I thought I read somewhere that the rover batteries are only good for a certain number of charge/discharge cycles, and that (if nothing else), this will limit the lifetime of the rovers.

However, despite several minutes of searching (even resorting to using the competitor's search engine) I can't find anything giving an actual maximum life expectancy number.

--Greg

There are PDF's at the JPL tech reports server that discuss it - and at 1000 cycles, something like 80% capacity should remain.

Doug