NASA's Kilopower nuclear reactor would be a space exploration game changer

NASA's Kilopower nuclear reactor would be a space exploration game changer
© Getty Images


Last year, NASA conducted a successful test of a new nuclear power generator called Kilopower under a program called Kilowatt Using Stirling Technology or KRUSTY for short. The generator ran a series of tests between November 2017 and March 2018, ending in a full-power trial that proved its effectiveness and safety. Since then the space agency has been examining a flight test of the technology.

One of the limiting factors for any space mission has been the amount of electric power a spacecraft can generate. Solar panels are most often used because they are relatively cheap, and sunlight is plentiful in the inner solar system. A type of nuclear battery called the radioisotope thermoelectric generator is the preferred power source for the outer solar system, i.e. Jupiter and beyond, where the sun’s light is dim.


Both solar panels and RTGs can only generate so much power. Furthermore, plutonium-238, the fuel used by RTGs, is in short supply. Its production is an expensive and time-consuming process.

By contrast, a kilopower unit uses readily available uranium-235. Moreover, the unit NASA tested could put out a full kilowatt of electricity. The space agency will be able to produce models that can generate 10 kilowatts. By contrast, the RTG powering the New Horizons space probe, which explored Pluto and more recently a Kuiper belt object dubbed Ultima Thule, puts out 245 watts.

Kilopower technology has numerous applications. One early use would be as a recharging station for battery-powered rovers on the lunar and Martian surfaces, eliminating the need for solar panels. A rover on the moon, thus recharged, could operate during lunar night and not have to go into sleep mode, as the Chinese Chang’e 4 must do.

Several clustered kilowatt units could provide enough electricity to power a lunar base or a Mars outpost. The technology fits right into NASA’s current plans to return to the moon and to establish a permanent presence there.

Scientists are especially excited at what kilopower technology can do for outer solar system exploration. Nearly every spacecraft that has gone to Jupiter and beyond has used RTGs. Kilopower will not only be able to expand the capabilities of deep space probes but will make it possible to launch more of them, since fuel will not be a limiting factor. Kilopower will not only be able to power the spacecraft but provide energy for electric rockets.

Several types of electric rockets use electricity to ionize propellant. Electric rockets provide low but long-lasting thrust that accelerates to tremendous speeds over time, which makes them suitable for outer planet explorations. Spacecraft that have used electric rockets, such as NASA’s Dawn mission to the asteroid belt, have used solar panels as a power source.


Kilopower could enable a long list of missions. For example, NASA would like to send probes to orbit Uranus and Neptune. The space agency would also like to take a closer, more extended look at Titan and Enceladus, moons of Saturn.

NASA has imagined many Earth-bound applications for kilopower technology. A kilopower unit could provide electricity for remote military bases, disaster relief operations where the electric grid has failed, and unpiloted undersea vehicles.

Of course, just because the technology is available does not mean that it will be used to its full potential. Space missions run on funding just as much as they do on power. Congress will have to provide the money for the voyages of scientific discovery that kilopower technology enables. Engineering provided NASA with the new nuclear generators. Good political deal-making will be needed to make use of them.

Mark R. Whittington is the author of space exploration studies “Why is It So Hard to Go Back to the Moon? as well as “The Moon, Mars and Beyond.”