If you've seen the next Mar's rover, named Curiosity (part of the Mars Science Laboratory-- or MSL as it's called for short), you've probably noticed that it's does not have solar panels, and that's because it does not need them. NASA has opted for a more reliable miniature nuclear reactor to serve as Curiosity's main power source.
It almost sounds like something out of Isaac Asimov's Foundation where nuclear energy power everything from ships to handguns, but it's true.
A few days before the rover's scheduled launch on November 25, NASA scientists will install the Multi-Mission Radioisotope Thermoelectric Generator. The generator is equipped with thermocouples that convert the heat generated from the natural decay of the plutonium dioxide into electricity. The power supply can provide Curiosity with a constant 110 watts of electricity that will allow the rover to travel farther than previous rovers and use more powerful analytical tools, all while continuously recharging its batteries.
NASA decided to use this alternative power source in place of solar panels because the Curiosity rover is like a compact car in comparison to its RC-car predecessors, Opportunity and Spirit. Curiosity weighs in at 2,000 pounds and measures 10 feet long, 9 feet wide, and 7 feet tall, which makes it twice as heavy and five times larger than the last two rovers.
The scientists also hope that the internal power system will also be more reliable in the dusty Martian environment than the solar panels on earlier rovers that were rendered useless in the planet's winter.
The craziest thing about these radioisotope power sources is that they have been in use since the Apollo moon missions.