NASA, Department of Energy testing ‘Kilopower’ space nuclear reactor

Collin Skocik

In preparing for possible missions to the Red Planet in the near future, NASA’s Space Technology Mission Directorate (STMD) has been given the go-ahead to test a small nuclear reactor that could one day run equipment on the Martian surface.

The Kilopower project is working to advance a design for a compact, low-cost, and scalable nuclear fission power system for missions that require lots of power, such as a human mission to Mars. The technology uses a fission reactor with a uranium-235 reactor core to generate heat, which is then transferred via passive sodium heat pipes to Stirling engines. Those engines use that heat to create pressure, which moves a piston – much as old coal-powered ships used steam pressure to run their pistons. When coupled to an alternator, the Stirling engine produces electricity.

“What we are striving to do is give space missions an option beyond RTGs [radioisotope thermoelectric generators], which generally provide a couple hundred watts or so,” Lee Mason, STMD’s principal technologist for Power and Energy Storage at NASA Headquarters in Washington, D.C., said in a NASA news release. “The big difference between all the great things we’ve done on Mars, and what we would need to do for a human mission to that planet, is power.”

Mason said the new technology could provide kilowatts of power and even be upgraded to provide hundreds of kilowatts or even megawatts of power.

“We call it the Kilopower project because it gives us a near-term option to provide kilowatts for missions that previously were constrained to use less,” Mason said. “But first things first, and our test program is the way to get started.”

The test program

The next step for Kilopower project hardware is to be subjected to a full-power test for some 28 hours.

“The upcoming Nevada testing will answer a lot of technical questions to prove out the feasibility of this technology, with the goal of moving it to a Technology Readiness Level of 5,” said lead researcher Marc Gibson, “It’s a breadboard test in a vacuum environment, operating the equipment at the relevant conditions.”

Mason acknowledges the contributions of the Department of Energy and the National Nuclear Security Administration’s infrastructure, as well as the Los Alamos National Laboratory in New Mexico.

The hardware for the Kilopower project was designed at built at NASA’s Glenn Research Center in Cleveland. NASA’s Marshall Space Flight Center in Huntsville, Alabama, developed the test plan and will operate the tests. The reactor core comes from the Y12 National Security Complex in Oak Ridge, Tennessee.

A ‘game changer’ technology

A fission-powered, Sun-independent power source would be a game changer, according to Mason.

“It solves those issues and provides a constant supply of power regardless of where you are located on Mars,” Mason said. “Fission power could expand the possible landing sites on Mars to include the high northern latitudes, where ice may be present.”

Previous NASA missions – including the landmark Apollo Moon landings of the 1960s and 1970s – have used RTGs. The Viking Mars landers, the Curiosity rover, the Voyager spacecraft, the New Horizons probe to Pluto, and the Cassini mission to Saturn all used plutonium-run batteries that drew their power from the natural decay of their radioisotope heat source.

Patrick McClure, project lead on the Kilopower work at the Los Alamos National Laboratory, said that a space nuclear reactor could provide a high-energy density power source with the ability to operate independent of solar energy or orientation, and the ability to operate in extremely harsh environments, such as the Martian surface.

Additionally, the Kilopower team believes the technology could be applicable to multiple NASA missions.

“We ultimately hope that this is the first step for fission reactors to create a new paradigm of truly ambitious and inspiring space exploration,” said David Poston, chief reactor designer at Los Alamos.

In addition to providing an independent power source, the Kilopower project would also enable modular units to be dropped by a single lander and subsequently operated independently by various Mars landing missions.

Mason said the technology could also be used in a variety of environments and destinations.

“The technology doesn’t care,” Mason said. “Moon and or Mars, this power system is agnostic to those environments.”

Video courtesy of NASA