Those two hearty little rovers that we sent to Mars way back in 2004 could have hit the final stretch of their life. Ferocious dust storms have enveloped the areas in which they've been operating, limiting the amount of power their solar arrays can generate. The image below shows the successive darkening of the skies over the Opportunity rover's position on the Merdiani Planum.This problem seems to effect the rover Opportunity more than Spirit. Prior to the dust storm, Opportunity's solar arrays were churning out 700 watt hours of electricity in a day. Since the storm has hit, that output has dropped to 128 watt hours. NASA has ceased all but the most essential operations hoping to conserve enough power to keep the little rovers internal heaters working. If they can not, then the components inside will freeze and the rover's electronics will cease to function.
I've grown quite attached to these little guys. They've returned a hell of a lot of good science. Compared to many NASA missions, these two little bots have been an absolute bargain. They were designed to function for 90 days have surpassed that landmark by far. For three years they've churned along and in the process they've definitively proved that Mars was once awash in water. They've also set the benchmark for ruggedness and increased our knowledge in the arena of robotics and engineering.
I sure hope that these two little guys can keep it together and weather out the dust storm. I've always known that some day, their signal would fall silent but let's just hope that that time has not yet arrived. Some have questioned the need for space exploration and look at it as a wasteful federal expenditure, but I can tell you that I believe with 100% certainty that we as a species must explore space if we wish to survive in the long run. It is only a matter of time until something comes along to threaten mankind as a species be that the impact of a meteor or comet, a disease, a war or some unforeseen tragedy. When that event arrives, it sure would help to have redundant populations of humans somewhere else for safe keeping. Further, space offers us access to mineral wealth such as we have never had access to before. While I do believe that it is high time for private industry to move into the realm of space exploration, I also believe that federal spending for this exploration is money well spent... Especially when it buys us a pair of troopers like Spirit and Opportunity!