Comment Re:90 days? (Score 5, Informative) 147
I'd like to point out that the engineers designing the rovers probably expected them to last longer than that (though certainly not 5 years). They probably budgeted for 90 days to keep the projected costs down so that NASA would chose the project. They knew that the budget would be extended once the rovers were there.
A lot of people seem to believe this, but it's really not true. I'm not saying we expected the rovers to drop dead at the stroke of midnight on sol 91, but even the wildest optimists on the project did not openly dare to hope that we'd even double that 90-sol lifetime. (We've just hit twenty times that number, as it happens. Incredible!)
Also note that underestimating surface survival time doesn't significantly reduce costs. Getting through the first 90 sols on Mars cost a little over $800 million. But most of that cost goes into design, development, testing, launch (about $100 million per rover goes to launch costs alone, IIRC), and so on. Operations, by comparison, is cheap: now that they're there, we run the rovers for ~ $20 million per year. If we'd known, for example, that we'd survive a year on the surface, we could have promised NASA four times the science for a ~ 10% cost increase; that would have made the project a better sell, and we'd have been fools not to do it.