What might the SR-1 look like? MIT Technology Review<\/em> saw a presentation by Steve Sinacore, program executive of NASA\u2019s Space Reactor Office, that offers some clues. So far, the concept art makes it look like a colossal fletched arrow. At the back will be the power-and-propulsion system, while its tip will hold a 20-kilowatt-or-greater uranium-filled nuclear reactor. (For context, a typical nuclear plant on Earth is 50,000 times more powerful, producing a gigawatt of power.)\u00a0<\/p>\n NASA<\/p>\n<\/figure><\/div>\n The \u201cfletches\u201d on SR-1 are large fins that allow the reactor to cool down. \u201cYou have to have really large radiators,\u201d says Holmes, since the nuclear fission process produces so much heat that much of it has to be vented into space\u2014otherwise, the reactor and spacecraft will melt.<\/p>\n According to that presentation, the spacecraft\u2019s hardware development is due to start this June. By January 2028, SR-1\u2019s systems should be ready for assembly and testing. And by that October, the spacecraft will arrive at the launch site, ready for liftoff before the year\u2019s end. Will the nuclear reactor manage to hold itself together? \u201cGoing through the launch safely is going to be a challenge,\u201d says Middleburgh. \u201cYou are being shaken, rattled, and rolled.\u201d\u00a0<\/p>\n Then, he says, \u201conce you\u2019re up in space, once you\u2019ve got through that few minutes of hell in getting there, it\u2019s zero-gravity considerations you have to worry about.\u201d The question then becomes: Will the mechanics of the reactor, built on terra firma, still work?\u00a0<\/p>\n For safety reasons, the nuclear reactor will be switched on around two days post-launch, when it\u2019s comfortably in space. Uranium isn\u2019t tremendously dangerous by itself, but that can\u2019t be said of the nuclear waste products that emerge when the reactor is activated, so you don\u2019t want any of that to fall back to Earth.\u00a0<\/p>\n If this schedule is adhered to, and SR-1 works as planned, it\u2019s expected to reach Mars about a year after launch. \u201cIt\u2019s an aggressive timeline,\u201d says Holmes, something she suspects is being driven partly by China\u2019s and Russia\u2019s own deep-space nuclear ambitions. The two countries aim to place their own nuclear reactor on the moon\u2019s surface to power the planned International Lunar Research Station\u2014a jointly operated lunar base\u2014by 2035.\u00a0<\/p>\n Whether it flies or fails in space, SR-1\u2019s operations should help NASA with putting a nuclear reactor on the moon soon after. \u201cAll of the things we\u2019d be learning about how that system operates in space [are] very helpful for a surface application, because basically it\u2019s the same,\u201d says Corbisiero. \u201cThere\u2019s still no air on the moon.\u201d<\/p>\n And if SR-1 does triumph, it will be a game-changing victory for NASA. It will also be \u201ca massive win for the human race, frankly,\u201d says Middleburgh. \u201cIt will be a marvel of engineering, and it will move the dial in humans potentially taking a step on Mars.\u201d Like many of his colleagues, including Holmes, he remains thrilled by the prospect of the first-ever nuclear-powered interplanetary spacecraft\u2014even with the incredibly ambitious timeline.\u00a0<\/p>\n \u201cThese are the things that get us up in the morning,\u201d he says. \u201cThese are the sorts of things we will remember when we\u2019re old.\u201d![\"Annotated](\"https:\/\/wp.technologyreview.com\/wp-content\/uploads\/2026\/04\/5-america-underway-in-space-on-nuclear-power-11.png?w=2500\")
<\/p>\n