NASA sets 2028 launch target for nuclear-powered spacecraft to Mars

SR-1 mission marks a $2 billion bet on nuclear electric propulsion for interplanetary travel

By LineZotpaper

Published21 October 2026

Read Time2 min

NASA has announced Space Reactor 1 Freedom (SR-1), the first nuclear reactor powered interplanetary spacecraft, with an uncrewed mission to Mars slated for a late 2028 launch and a 2029 arrival. The project represents a significant commitment to nuclear electric propulsion, promising more efficient spaceflight and reduced radiation exposure for future astronauts.

The announcement, made shortly before the Artemis II lunar slingshot, generated enthusiasm from experts. 'You wake up to that announcement, and it puts a big smile on your face,' said Simon Middleburgh, co-director of the Nuclear Futures Institute at Bangor University. Philip Metzger, a spaceflight engineering researcher at the Florida Space Institute, agreed: 'I think it's a very doable technology.'

SR-1 will use nuclear electric propulsion, where a uranium-splitting reaction generates heat and electricity to ionize gas into thrust. Sebastian Corbisiero, the US Department of Energy's national technical director of space reactor programs, describes the approach as 'very low thrust, but very efficient,' allowing for sustained operation over long periods. NASA program director Steve Sinacore confirmed that procurement of major components is underway.

However, the path to launch has been fraught with delays. The US has started and terminated several nuclear propulsion programs over the past 75 years, with DRACO, a joint NASA and Department of Defense project, canceled as recently as 2025. The sticking points remain safety and cost. The reactor will only be switched on two days after launch, once safely away from Earth. 'Going through the launch safely is going to be a challenge,' Middleburgh warned.

Lindsey Holmes, vice president of advanced projects at Analytical Mechanics Associates, suspects the aggressive timeline is driven partly by China's and Russia's own deep-space nuclear ambitions, which include plans for a reactor on the lunar surface in the mid-2030s. If SR-1 succeeds, the technology could directly inform NASA's own lunar reactor efforts, given the similarity of operating in a vacuum.

Analysis

Why This Matters

A successful flight would validate nuclear electric propulsion for deep-space missions, drastically cutting travel time to Mars and reducing astronaut radiation exposure.
The project is a direct precursor to NASA's goal of placing a reactor on the lunar surface to power a permanent base.
It re-establishes the US as a leader in nuclear space technology, a field where China and Russia are actively investing.

Background

While the Soviet Union successfully operated dozens of nuclear reactors in orbit during the Cold War, the US has repeatedly struggled to sustain its own nuclear space propulsion programs, with DRACO canceled in 2025. Space Reactor 1 Freedom marks a $2 billion commitment from NASA to break this cycle, leveraging the Idaho National Laboratory to build a 20-kilowatt reactor for an interplanetary mission.

Key Perspectives

NASA and its industry partners: They view SR-1 as a necessary, achievable advancement that leverages existing technology, with the potential to make the Solar System accessible. They point to steady integration progress. Scientists and engineers: While broadly supportive, they flag the significant safety hurdles, particularly the challenge of ground testing a highly powerful reactor and ensuring it survives a rocket launch intact. International competitors (China and Russia): Their joint plans for a lunar surface reactor by the mid-2030s act as a major competitive driver, pushing NASA towards an accelerated, higher-stakes timeline.

What to Watch

Whether the Idaho National Laboratory meets its late-2028 delivery deadline for the SR-1 reactor.
The outcome of the Artemis program's lunar infrastructure plans, which are closely tied to SR-1's development.
Any new public milestones from China and Russia on their joint deep-space nuclear reactor initiative.

Sources

Nuclear-powered spaceships · MIT Technology Review

Checked

11 claims in this story checked against 1 source: 8 supported.

Show each claim

SupportedNASA has set a late-2028 launch target for SR-1’s uncrewed Mars mission, with arrival in 2029.MIT Technology Review: “SR-1, the first-ever nuclear-reactor-powered interplanetary spacecraft, is meant to fly an uncrewed mission to Mars by the end of 2028, arriving in 2029.”
SupportedSR-1 is a $2 billion bet on nuclear electric propulsion.MIT Technology Review: “After much wavering, it now appears that nuclear-powered interplanetary travel is a $2 billion bet NASA is willing to make.”
SupportedSR-1 is the first nuclear-reactor-powered interplanetary spacecraft.MIT Technology Review: “SR-1, the first-ever nuclear-reactor-powered interplanetary spacecraft”
Partly supportedThe mission promises more efficient spaceflight and reduced radiation exposure for future astronauts.MIT Technology Review: “A successful mission would herald a new era of more efficient, potentially faster spaceflight—saving astronauts time and cutting their exposure to harmful cosmic radiation as they travel to Mars and beyond.”
SupportedMiddleburgh said, “You wake up to that announcement, and it puts a big smile on your face.”MIT Technology Review: ““You wake up to that announcement, and it puts a big smile on your face,” says Simon Middleburgh, co-director of the Nuclear Futures Institute at Bangor University in Wales.”
SupportedMetzger said, “I think it's a very doable technology.”MIT Technology Review: ““I think it’s a very doable technology,” says Philip Metzger, a spaceflight engineering researcher at the Florida Space Institute.”
SupportedCorbisiero described the approach as “very low thrust, but very efficient.”MIT Technology Review: “The approach “is very low thrust, but very efficient,” says Sebastian Corbisiero, the US Department of Energy’s national technical director of space reactor programs.”
SupportedMiddleburgh warned, “Going through the launch safely is going to be a challenge.”MIT Technology Review: ““Going through the launch safely is going to be a challenge,” says Middleburgh.”
SupportedSinacore said procurement of major components is underway.MIT Technology Review: ““Procurement of major components is underway, and integration work on the power and propulsion element is advancing steadily,” Sinacore told MIT Technology Review.”
Partly supportedThe path to SR-1’s launch has been fraught with delays.MIT Technology Review: “Still, developing space propulsion using reactors has been slow going. The US has started—and terminated— several programs looking into it over the past 75 years.”
Partly supportedSafety and cost remain the sticking points for SR-1.MIT Technology Review: “The project was canceled because of high experimentation costs, an inability to compete with conventional rocket propulsion on price, and difficulty ensuring that ground tests could be performed safely and effectively.”