A Nuclear Reactor for Space Missions Passes Final Major Ground Tests

An artist’s rendering of a Kilopower nuclear power plant on the surface of the moon. The prominent heat radiator makes it look like a beach umbrella. The actual unit will have cables carrying electricity away from the reactor. Credit: NASA
Scientists, engineers and reporters gathered at NASA’s Glenn Research Center in Cleveland on May 2 for a news conference announcing the latest results of the Kilopower nuclear power plant project: It has finished all of its major ground tests and met or surpassed the development team’s expectations. 

By Harrison Tasoff | SPACE.com

NASA is developing the experimental reactor to provide reliable energy for long-duration crewed missions to the moon, Mars and destinations beyond.

For decades, spacecraft have relied on nuclear power as a compact, reliable source of electricity, especially on missions for which solar power is not feasible, like expeditions to the moon’s polar regions. The Voyager 1 and 2 spacecraft, which are now billions of miles from the sun, still have enough nuclear energy after more than 40 years to transmit signals back to Earth. Meanwhile, the Curiosity rover has been driving around the Red Planet for nearly six years courtesy of a trunk full of plutonium. [Nuclear Generators for NASA Deep Space Probes (Infographic)]

In spacecraft like the Voyagers and Curiosity, a device called a radioisotope thermoelectric generator (RTG) converts heat energy from passive radioactive decay directly into electricity. The decay causes a temperature difference across plates of two kinds of metal — one connected to the reactor, and the other attached to a radiator, thereby producing a voltage. This component, called a thermocouple, is commonly used in thermometers and temperature sensors. Although RTGs are not particularly efficient, they are simple and have no moving parts, making them perfect for applications in which repair is not an option.

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