NASA Aims to Launch the World’s First Planet-Hopping Spacecraft Powered by Nuclear Fission

The agency wants the mission to head to Mars by the end of 2028

Sara Hashemi | Daily Correspondent

March 25, 2026

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NASA has big, potentially revolutionary plans coming up.

On March 24, the agency announced that it wants to send a nuclear-powered spacecraft to Mars by the end of 2028. If successful, it would be the first probe to use nuclear propulsion to travel beyond Earth’s orbit.

The spacecraft, called Space Reactor-1 (SR-1) Freedom, will rely on an onboard fission reactor. This type of device provides power by splitting atoms, usually uranium, which releases energy that can be transformed into electricity. Once SR-1 Freedom reaches Mars, it will drop three helicopters that will search the planet for underground water and potential landing sites for missions carrying humans. After completing that goal, the spacecraft might continue chugging along to investigate other worlds.

SR-1 Freedom will “ultimately unlock the capabilities necessary for sustained exploration beyond the moon and missions to Mars and the outer solar system,” NASA Administrator Jared Isaacman said during a press event.

Most spacecraft can’t travel to the edge of the sun’s domain because that would require enormous amounts of liquid fuel, reports Scientific American’s Claire Cameron. Only three NASA missions have made it that far: the two Voyagers, launched in 1977, and New Horizons, launched in 2006, which are all powered by decaying plutonium. These spacecraft rely on a type of nuclear energy, and the devices that convert heat from the radioactive decay into electricity are sometimes called “nuclear batteries.” They provide low, steady power.

Atom-splitting nuclear fission, on the other hand, can provide more power, but has not been tested for space travel by the United States since the 1960s. Meanwhile, Russia has used dozens of fission reactors in space, according to the World Nuclear Association.

Despite the United States’ decades-long gap in attempting to use nuclear reactor technology for spacecraft, “NASA has been studying this for a very long time, along with the Department of War,” said Steve Sinacore, NASA’s program executive for fission surface power, at a separate press event. The “technology is available.”

He added that knowledge of design and engineering-level hardware exists in industry as well. “To me, it is a maturing of that technology that currently exists and then an integration into a vehicle,” Sinacore said.

Still, some scientists worry that the SR-1 Freedom’s planned helicopters might be too small to carry robust tools to study Mars, reports Science’s Paul Voosen. They are currently slated to have cameras, ground-penetrating radar and radios.

“We will have to see how much new science will be enabled,” Briony Horgan, a planetary scientist at Purdue University, tells the outlet, noting that many researchers have already planned the investigations they want to see on the Red Planet. “It would be a major loss if that program was exclusively replaced with science slapped onto other efforts.”

NASA hopes this mission will help them prepare for the Lunar Reactor-1 (LR-1), a fission surface-power system that should provide electricity to a planned moon base. The lunar base project’s first two phases will receive about $20 billion over the seven years, Isaacman said during the event. Some of the equipment that will go toward it is being repurposed from a mostly-built space station that was supposed to orbit the moon, which the agency has now paused.

Editors' note, March 26, 2026: An earlier version of this story incorrectly stated that the Artemis program shakeup was announced earlier this month. 

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Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.