What Is Kilopower? NASA’s Mini Nuclear Reactor Could Power Life on Mars

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What NASA's Kilopower devices may look like arrayed on Mars. NASA

Updated | On Thursday, NASA announced new tests are underway for the Kilopower project, a program designed to create small nuclear power sources to fuel further space exploration. A prototype, which was created by NASA and the Department of Energy, has completed non-nuclear tests and is now running with a real reactor core at a facility in Nevada. Tests on the system are expected to continue into the spring.

Kilopower tackles a few different problems in spacecraft design: existing nuclear power systems rely on a fuel we've essentially run out of, solar power becomes increasingly feeble the further from the sun the spacecraft goes, and more complicated space activities—like those involving humans—would require significantly stronger power supplies than current projects.

“It would have a tremendous impact enabling missions that otherwise aren’t attainable,” Lee Mason, a NASA energy specialist, said during a press conference. “It would enable us to mine the resources on Mars.” Mars is a particularly tricky place to use solar energy—not only is it farther away from the sun, but its nights are longer and giant dust storms can cloud its surface for weeks on end.

In addition to powering activities on the surface of the moon and Mars, the agency also hopes Kilopower systems could power robots as they explore the outer planets and their moons, or even take a probe beyond the boundaries of our solar system.

Scientists working on the Kilopower project are designing a set of small nuclear fission plants that would be safe to operate in space. The plants run on uranium, unlike previous space-bound nuclear systems, which use plutonium. Each individual unit will produce between one and 10 kilowatts, and multiple units could be stitched together to power thirstier systems, like habitats that can keep humans safe on Mars. For comparison, current rovers run off just 200 watts or less of energy.

Read more: Watch Live: NASA to Reveal Energy Breakthrough That Can Take Humans to Mars and Power a Home for 10 Years

As anyone would be with any nuclear power system, NASA is worried about safety. One easy step is to keep the system turned off until it arrives at its destination—although the tests are being run here on Earth, the final system won't be operational on our planet. “We would not operate the reactor until we reached deep space or a planetary surface,” Pat McClure, a nuclear specialist at Los Alamos National Laboratory who has been working on the Kilopower project, said. They're also building in a range of redundancy and safety features.

There are four phases of testing, beginning with the core itself and gradually building out the entire system. The current tests will culminate with a test in March when the team plans a 28-hour run at full power with all components in place to make sure everything functions as expected. If all goes smoothly, the energy source could offer space exploration missions of the future some much-needed muscle.

This story has been updated to include more information about the challenges of solar power on Mars.