NSA has successfully tested a design for a small nuclear-fission reactor, the Kilopower, that could provide a reliable source of power on the Moon.
Current space missions, reports Scientific American, use fuel cells, nuclear batteries or solar power, but each source has drawbacks. A a night on the Moon lasts two weeks, and the strength of sunlight on Mars is only 40% that of earth. “When we go to the moon and eventually on to Mars, we are likely going to need large power sources not dependent on the sun, especially if we want to live off the land,” says Jim Reuter, NASA’s acting associate administrator for space technology.
Kilopower is a small, lightweight fission reactor that can provide up to 10 kilowatts of electricity, enough to power three to eight typical American houses — and enough to power a human outpost on the Moon or Mars.
Nuclear energy can be used in two ways: for generating electricity or for propulsion. NASA envisions using Kilopower to generate electricity, although in theory nuclear power can be adapted to drive a spacecraft.
A different type of nuclear power — radioisotope thermoelectric generators, or RTGs — use radioactive decay to generate electricity, and NASA has used it to power dozens of deep-space craft. RTG efficiency is extremely low, however, and plutonium oxide fuel is in short supply. There is enough in the nation’s stockpile to power only NASA’s Mars rover and one or two other potential missions.
Kiopower uses nuclear fission, which splits atoms to produce energy. After several years in development, NASA tested the technology in a 28-hour run in which the reactor was turned on, operated at full power at temperatures of 800 degrees Celsius, than cooled and shut down. The test reactor produced more than 4 kilowatts.
Writes Scientific American:
NASA and DoE officials say the reactor is safer than previous generations because of how it works. The fission chain reaction is passively controlled and can even be stopped, using boron control rods and beryllium reflectors. Atom-splitting would not begin until after the reactor is far from Earth. If a reactor or its rocket exploded on the launch pad, the uranium 235 in the core would expose people one kilometer away to radiation levels no more than natural background levels, according to Patrick McClure, Kilopower project lead at the DoE’s Los Alamos National Laboratory. “Under all worst-case situations, we don’t believe there is any chance the reactor would come on accidentally during a launch accident,” he says.
The next step is to test the reactor in space. NASA, which has not yet approved such a mission, expects to devote the next 18 months to figuring out how a rest flight would work. One possible scenario is to fly a small Kilopower reactor on a lunar lander.