By Peter Hill
In 2012, the Mars Science Laboratory (MSL)  successfully touched down on the Red Planet. Aptly named Curiosity, it brought with it scientific discovery instruments and exploration capabilities that only a nuclear-powered rover could realistically possess.
While not the first rover to successfully land on Mars, a distinction that goes to Sojourner deployed by the Mars Pathfinder in 1997 and followed by the wildly successful Mars Exploration Rover (MER) pair Spirit and Opportunity that landed in 2004 , Curiosity was the first rover powered by nuclear energy.
Much like the MERs exceeding their planned 90-day mission life by 2500+ Martian days (sols) in the case of Spirit and 5000+ in the case of Opportunity; Curiosity has also far exceeded its original two-year mission lifespan by many years and is still going strong. All of these rovers are a testament to American engineering prowess and demonstrate the benefits of a robust space exploration manned or otherwise. As Curiosity heads into its 7th year it is continuing to yield significant insight in Mars’ history, geology, and whether the planet could have supported life sometime long ago. However, what sets Curiosity apart from Sojourner, Spirit, or Opportunity is its power source. Curiosity is powered by a multi-mission radioisotope thermoelectric generator (MMRTG) whereas Sojourner, Spirit, and Opportunity were all solar-powered. Mars is significantly further from the sun than Earth is, which makes solar power a challenge; harsh weather conditions especially during the Martian winter can render a rover powerless for months on end and Martian dust can degrade solar cell performance. Rather than utilize the sun, the RTG in Curiosity utilizes the heat emitted from a decaying plutonium isotope to generate electricity via thermocouples. In addition to improving the performance of the rover in the harsh Martian climate, this RTG has also allowed Curiosity
By Peter Hill