Nuclear Rockets Are Coming

How Splitting Atoms In Space Accelerates Everything

TLDR: Power is the innermost loop, on Earth and in space. NASA’s new Administrator, Jared Isaacman, is restarting the agency’s nuclear program, compact reactors on the Moon and atomic engines in deep space, and it could cut the trip to Mars from nine months to three. Chemistry got us off the planet. Fission is how we take the solar system.

Every ounce of propellant that has ever moved a human being through space was lifted off Earth’s surface. Every single ounce. We spent 60 years clawing out of one gravity well only to drag along every drop of energy we would ever need, sloshing in a tank. The most expensive way to travel ever devised.

Chemistry is the problem. A hydrogen-oxygen rocket, the best chemical engine we have, converts a laughably tiny fraction of the energy locked in its fuel into motion. Jared framed the energy ladder better than anyone I have heard.

“Chemical propulsion pulls an almost immeasurably small fraction of the energy in matter. Fission gets you to a tenth of one percent. Fusion, half a percent. The destination is antimatter annihilation.”

— Jared Isaacman, NASA Administrator (paraphrased from the pod)

That is the unlock Jared is chasing, and he is chasing it on two fronts at once: keeping the lights on at a Moon base, and lighting a fire under a spaceship.

POWER ON THE MOON

Start with the obvious objection. The Moon has no atmosphere, no clouds, and free sunlight. Why haul a reactor a quarter million miles when you could just unfold solar panels? Because the Moon runs on a brutal clock: roughly 14 Earth-days of sunlight followed by 14 Earth-days of total darkness. To survive 336 straight hours of night on solar, you need a massive battery farm. Every square meter of solar array and every kilogram of storage has to be lifted out of Earth’s gravity. Solar on the Moon is a mass problem wearing a free-energy costume.

Fission flips the arithmetic. Compact, and always on. It does not care where the Sun is.

This isn’t a concept. It’s a system under construction. NASA’s Fission Surface Power project, with the Department of Energy and Idaho National Laboratory, is building a 40-kilowatt reactor, enough to run a base of four to six astronauts, their habitats, rovers, and ice-mining gear. HALEU fuel (uranium enriched to 19.75 percent), under 6 metric tons, inside a 4-meter cylinder, running 10 years autonomously with no human touch. NASA wants a lunar-ready variant by 2030, orbital testing as early as 2028.

“Without nuclear, you’re going to need a lot of Optimus robots on Mars walking around dusting off all the solar panels.”

— Jared Isaacman, NASA Administrator

Picture it. The most advanced humanoid robots ever built, on another world, employed full-time as janitors for a solar farm.

ATOMIC ENGINES, THE REAL UNLOCK

Surface power is the appetizer. Propulsion is the main course, and it is the most exciting thing Jared during our entire Moonshots podcast. Here is the number that matters. Specific impulse (expressed in “second”) is measure of merit for rockets. Our best chemical engines top out around 450 seconds. A nuclear thermal engine, which runs hydrogen through a reactor core instead of burning it, hits 800 to 1,000 seconds. Two to three times the efficiency, which in rocket math is the difference between crawling and sprinting.

What does that buy you? A chemical trip to Mars is a 6-to-9-month one-way grind. Nuclear can cut that to roughly 3 to 4 months. Cut the transit in half and you halve your crew’s radiation dose, halve the muscle and bone loss, and halve the supplies you have to pack. Speed is not a luxury in deep space. It is a life-support system.

NASA and DARPA had a nuclear thermal demonstrator called DRACO aimed at a 2027 flight. It got trimmed in 2025, but the knowledge folded back into NASA, and Jared’s version is arguably smarter. His first move is not the fastest engine. It is the first one that actually flies.

That vehicle is called “SR-1 Freedom” – the first nuclear power-and-propulsion spacecraft, and almost all of it is repurposed hardware. The body is the Power and Propulsion Element built for the Gateway lunar station, electric thrusters already integrated. The reactor baseline comes from components matured at Idaho National Laboratory over decades, largely paid for by other agencies. When Politico said the administrator wants to spend $2.5 billion on a nuclear spaceship, Jared’s answer was that taxpayers already spent it. He just refuses to let it rot in a warehouse. Then he gave the analogy that made the whole thing click.

“This is what Nautilus was. A diesel boat repurposed as a nuclear sub. Rickover said it was a 70% solution, but it gave birth to the nuclear navy. We’re doing the exact same thing.”

— Jared Isaacman, NASA Administrator

The history checks out. USS Nautilus put a revolutionary reactor inside a conventional diesel-era hull. Admiral Hyman Rickover refused to invent the reactor and the hull at once. Solve one impossible thing per vehicle. Nautilus was not the best submarine ever built. It made every submarine after it possible. SR-1 will not knock your socks off. SR-2 will be better. And as Jared put it, we are not jumping straight to Battlestar Galactica.

What gets optimized between versions is material science. Run the reactor hotter and you shed mass, because you stop needing radiators the size of football fields to dump waste heat. Improve power conversion and nuclear starts beating solar even inside Jupiter’s orbit. Past Jupiter, where sunlight is a rumor, there is no argument left. Nuclear is the only thing that works. That is what finally makes probes to Enceladus, Uranus, and Titan routine instead of once-a-generation.

Nuclear propulsion is the way humanity navigates our Earth-Moon-Mars-Solar System future. While its not a warp-drive yet, it beats burning propellants out the rear of a rocket.

Issacman believes NASA gets crew to Mars first, not SpaceX, for one reason: NASA does not do one-way missions. You want the crew home to talk about it. The moment you require a round trip, your dependency on chemical propulsion has to collapse, because making return propellant on another planet is savagely hard. So the architecture is chemically augmented nuclear electric propulsion. First crew of four, a roughly three-year round trip with about 30 days on the Martian surface, inside a 10-to-15-year window.

“The ultimate goal is to bring astronauts to Mars and back with the fewest miracles required. That may not be the fastest way, but if it doesn’t require cryogenic refueling, that’s a win.”

— Jared Isaacman, NASA Administrator

The fewest miracles required. I have been collecting phrases from engineers for 30 years and that one goes straight into the permanent file. If we scratch and claw our way to Mars on chemical propellant, we end up with a re-run of Apollo: a flag, a footprint, a ride home, and nothing you can build on. Do it with nuclear and you have a road. A rotation. A supply line. The difference between a stunt and a settlement.

WHAT THIS MEANS FOR YOU

If you’re an entrepreneur: The supply chain for space nuclear barely exists. High-temperature materials, compact power conversion, and autonomous reactor control are wide open, and the materials work sells straight into terrestrial small modular reactors.

If you’re an executive: Jared found $2.5 billion of finished hardware in a warehouse and shipped it as a product. Audit what your organization has already paid for and abandoned.

If you’re an investor: Lunar and deep-space nuclear are now national space policy, which means a decade of procurement. Track the Fission Surface Power teams and the HALEU fuel supply chain.

If you’re a student: Nuclear engineering plus materials science is about to be the most leveraged skill pair on the planet, on Earth and off it. Pick that major.

If you’re a parent: A child born today will be in their teens when four humans leave for Mars on an atomic ship. Tell them the Moon gets 14 days of night. Better physics hook than the textbook.

For 60 years we have been prisoners of chemistry, hauling every drop of fuel up from Earth and creeping to other worlds on the least energetic reaction we know how to control. Jared is betting we break out this decade: a reactor humming through the lunar night by 2030, an atomic tug assembling in orbit, and a trip to Mars that shrinks from nine months to three.

We have barely scratched our own solar system. With Nuclear doing the pushing we have a chance to make accelerate everything.

To a future of abundance,

Peter