NASA announces nuclear Mars mission

Just before Artemis II's lunar slingshot in April, NASA announced Space Reactor-1 Freedom, the first nuclear-reactor-powered interplanetary spacecraft, planned for uncrewed Mars launch by end of 2028, arriving 2029.

“You wake up to that announcement, and it puts a big smile on your face.”

Why nuclear power matters for space

A successful mission would enable more efficient, potentially faster spaceflight, saving astronauts time and cutting exposure to harmful cosmic radiation during travel to Mars and beyond.

Nuclear reactors in space aren't new

The Soviet Union sent dozens of reactors into orbit, often to power spy satellites. Experts say there are no major technical obstacles to making nuclear space propulsion work.

“I think it's a very doable technology. I'm happy to see them finally doing this.”

Decades of false starts

The US has started and terminated several nuclear space propulsion programs over 75 years. DRACO, a NASA and Department of Defense collaboration, ended in 2025 due to high costs, inability to compete with conventional rockets…

NASA commits two billion dollars

After wavering, NASA is now making a two billion dollar bet on nuclear-powered interplanetary travel using nuclear electric propulsion, which converts uranium fission heat into electricity to ionize gas for thrust.

“It is very low thrust, but very efficient. So you can use it for a long period of time.”

How SR-1 will look and work

The spacecraft resembles a colossal fletched arrow. The back houses the power-and-propulsion system; the tip holds a uranium-filled reactor with at least twenty kilowatts capacity. Large fins cool the reactor by radiating heat into space.

Launch safety and timeline

The reactor will be switched on around two days post-launch, when safely far from Earth.If SR-1 works as planned, its journey to Mars will take about a year.

“Procurement of major components is underway, and integration work on the power and propulsion element is advancing steadily.”

China and Russia accelerate competition

China and Russia have announced plans to place a reactor on the moon's surface in the mid-2030s to power a jointly operated lunar base. This geopolitical pressure may be driving NASA's aggressive timeline.

“It's an aggressive timeline.”

SR-1 paves path to lunar reactor

Whether SR-1 succeeds or fails, its development should help NASA place its own reactor on the moon. The technology involved in both projects is broadly similar, since both operate in a vacuum.