Thanks to fellow blogger Pied Type who sent me a link to a good WeatherChannel site describing NASA’s Curiosity Mars mission, about to enter its active phase Sunday night. The Curiosity rover is about the size of a MiniCooper car, weighing in at about 2,000 pounds. Looking at its picture got me wondering about its power. It’s interesting, and different from that on previous rovers.
Curiosity is powered by that really nasty and toxic radioactive stuff, plutonium. It is in an active stage of decay and therefore gives off heat. Heat means energy, hence power. This is a big improvement on a solar source like the other rovers because it isn’t limited by the weak light of the distant sun, nor by nightfall. On the other hand, the amount of power is still surprisingly small – the electric power generated is only 125 watts at the start of the mission and would wane to 100 watts in the unlikely case the mission lasted 14 years. This is tiny – imagine the juice of a 100 watt light bulb powering this thing! But it’s still about four times the power of one of the solar rovers.
That the rover’s design is so limited is a measure of the enormous difficulties of operating so very far away. Mars is ⅔ again as far from the sun as Earth, so far that it takes a radio signal 14 minutes to get from there to here, so whatever the rover does, it must do based on careful pre-programming. And it is a very hostile environment with very little air, almost a vacuum compared to Earth’s, and extremely cold temperatures. The radioisotope power plant is a help with that – its excess heat is used to keep the rover’s parts warm.
Needless to say, low power is quite limiting. The Wikipedia page on Curiosity’s design says its speed is about 98 feet per hour and that it is expected to traverse about 12 miles in its two-year planned mission, so despite the expense and hoopla, this is a fairly modest exploration. That’s not to say, however, that a manned mission would be that much better. This dry, frigid, and hostile rock is terribly remote and human beings would have to carry their Earth environment with them, air, water, food, a vehicle, fuel, a portapotty, and all the rest. No, in my opinion, robots like Curiosity are the only way to go to explore Mars. Here’s hoping its nasty fuel powers it to a great success!