Forbes’ James Conca writes about how a tiny nuclear reactor developed by NASA could power potential colonies on Mars and the moon. The restrictions of space travel and harsh environments on other planets require an energy source like nuclear fuel because it is energy-dense, providing a lot of energy in a small amount of mass. With a highly enriched uranium core the size of a paper towel roll, NASA’s Kilopower reactors (supplemented by solar panels and batteries) will power propulsion systems, scientific instruments, life support systems and communications equipment.