When reporters revisit President John F. Kennedy’s address to a joint session of Congress in 1961, it is often framed as a bold moment of promises made — and ultimately kept. The president vowed to land a man on the moon before the decade was out, and return him safely to the Earth. His challenge nevertheless ignited an American space effort that would stretch the boundaries of human exploration.
Curiously, however, the moon wasn’t the only goal or commitment outlined.
“An additional 23 million dollars, together with 7 million dollars already available, will accelerate development of the Rover nuclear rocket,” Kennedy added just moments after his call to place astronauts on the lunar surface. “This gives promise of someday providing a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself.”
Yet by the time his words echoed through the legislature, NASA and United States defense agencies were already exploring the use of atomic energy to accelerate spacecraft to speeds that chemical propulsion couldn’t match. Almost simultaneously, those same agencies were developing nuclear-thermal engines through initiatives known as Project Rover and Project NERVA — often considered precursors to the current Demonstration Rocket for Agile Cislunar Operations, or DRACO, program, which aims to develop a nuclear thermal rocket by 2027 to significantly cut space transit times to Mars.
At its peak, the Apollo program would consume nearly 4% of the national budget, and would come on the heels of today’s equivalent of a $30 billion Manhattan Project that ushered the world into the nuclear age. And yet, in the intervening decades, such bold promises for harnessing nuclear power in space would fall far short of those early ambitions.
“We’ve spent nearly $20 billion on nuclear (space) power since the 50s and the only system we currently have is a light-bulb sized, 100-watt radioisotope generator,” Bhavya Lal, former NASA Associate Administrator for Technology, Policy, and Strategy, told me on the Space Minds podcast.
Voyager 1 and Voyager 2 — the only two spacecraft to have reached interstellar space — employ the natural decay of plutonium-238 in their radioisotope thermoelectric generators to convert heat into electricity. NASA’s New Horizons interplanetary space probe, designed to study Pluto and its moons, also generates power through the natural radioactive decay of plutonium dioxide fuel, comparable to that of a household lightbulb in terms of wattage. It’s hardly the sort of the power that could lessen travel times to the red planet.
Lal, however, along with Roger Myers say they now hope to “confront that disconnect head-on,” with an upcoming Idaho National Lab-funded report, entitled “Weighing the Future: Strategic Options for U.S. Space Nuclear Leadership.”
The report, slated for release this summer, maps “the full space fission landscape — surface and in-space, civil and defense, government needs and emerging commercial markets,” Lal said. She and Myers conducted more than 100 interviews across NASA, DoD, DOE, national labs and commercial entities, while also reviewing comparable program postmortems, and evaluating historical nuclear efforts — like the Manhattan Project.
“Beyond Mars, we really don’t have a whole lot of solar power … and there is no way to do a whole lot of science without nuclear,” Lal added.
“We went to Pluto with a New Horizons mission [and] the probes whisked past Pluto. Why? Because we didn’t have the Delta V to go into orbit. So … all we have is basically 24 hours worth of data, which took a year to get back. [Because] we had a light bulb amount of power, and we had to split the power between sending data back and doing more science or processing data.”
“We just get so much more value for our money if we have nuclear,” she added.Meanwhile, as NASA’s own landscape shifts, commercial entities are exploring how their efforts might align with emerging policy priorities, and where those nuclear efforts might fit in.
In April of this year, Kristin Houston, president of L3Harris’ space propulsion and power systems, told SpaceNews that “we are finally at the cusp for both nuclear electric propulsion and nuclear thermal propulsion,” and that the company is monitoring NASA’s Fission Surface Power program, meant to develop nuclear power systems for both lunar and Mars surface operations.
It’s not clear what such developments could signal in this next era of space exploration, or whether they will involve nuclear energy in the ways Kennedy proposed. But as space infrastructure needs and developments ramp up, there is an open question of power.
“There’s companies that want to do other industrial processes on the moon,” Lal noted. “And then if we go to Mars, we are going to need to generate propellant on Mars for journeys back. Especially if we use chemical systems again, we need megawatts of power to be able to do that sort of thing. And that is not coming from solar or batteries or fuel cells.”
David Ariosto is co-host of the Space Minds podcast on SpaceNews, and author of the upcoming Knopf book, “Open Space.”
This article first appeared in the June 2025 issue of SpaceNews Magazine with the title “Kennedy’s other moonshot.”
