Factory-built nuclear microreactors for the places the grid forgot - land, sea, and the long dark of space.
On June 4, 2026, a small reactor in the Idaho desert went critical. Not a headline most people read over coffee. But in the narrow world of nuclear engineering, it landed hard: Antares had become the first privately developed advanced reactor to reach criticality under the U.S. Department of Energy's Reactor Pilot Program. The machine was called Mark-0. The company was barely three years old.
Antares does not look like the nuclear industry most people picture. No cooling towers. No decade-long licensing slog presented as a feature. Its product, the R1, is a reactor you can move - shielded, cradled, and sized to be trucked, shipped, and one day launched. The pitch fits on a bumper sticker: abundant energy from Earth to the asteroid belt. The strange part is how seriously you have to take it now.
Here is the tension that runs through everything Antares builds. Modern missions - a forward base, a research outpost, a ship at sea, a payload bound for deep space - need steady, dense power. The grid does not follow them. Diesel does, but only as far as the fuel convoy, and convoys are slow, expensive, and, in a war zone, a target painted on the road.
Renewables are wonderful where the sun shines and the wind blows on schedule. The military and the space program rarely get to choose the weather. What they need is a power source that is small, dense, runs for years without refueling, and does not require a national infrastructure project to install. For most of nuclear's history, "small" and "movable" were not words it answered to.
Jordan Bramble is an unlikely nuclear CEO. His resume runs through multidisciplinary engineering, a food-logistics startup he co-founded, and a stint at the White House Office of Management and Budget - the kind of path that teaches you how Washington funds things and how factories ship them. In 2023 he and co-founder Julia DeWahl started Antares on a contrarian premise: the bottleneck in nuclear is not physics, it is manufacturing.
The bet was that a reactor could be designed to be built repeatedly on a production line, instead of poured once in concrete and litigated for a decade. Get the design passively safe, get the supply chain in-house, and the slow, bespoke art of reactor-building turns into something closer to aerospace manufacturing. It is an obvious idea, which is usually a sign that the hard part is execution.
Jordan Bramble and Julia DeWahl start the company in Torrance, California, betting on factory-produced microreactors.
Early rounds fund a ~145,000 sq ft Torrance facility designed to produce roughly ten reactor units a year.
Antares is named one of 11 participants in the Department of Energy's Reactor Pilot Program.
A round led by Shine Capital - $71M equity, $25M debt - pushes total funding past $140M.
Selected for a proposed microreactor deployment at Joint Base San Antonio under the Air Force ANPI initiative.
First privately developed advanced reactor to reach criticality under the DOE Pilot Program, at Idaho National Laboratory.
Target: produce electricity from an advanced reactor in 2027, with first production deployments to U.S. military sites beginning 2028.
The R1 produces 100 kilowatts to 1 megawatt of electric power and runs six-plus years between refuels. Under the hood it is a careful stack of choices that all point at the same goal - safe, dense, and movable.
The customer list reads like a who's-who of institutions that do not buy on hype. The Department of Energy authorized the criticality test and runs the Pilot Program Antares competed into. Idaho National Laboratory hosted the Mark-0 demonstration. The Department of the Air Force selected Antares for a proposed deployment at Joint Base San Antonio. Investors followed: Shine Capital led the Series B, joined by Alt Capital, Caffeinated, FiftyThree Stations, and Industrious.
Antares states its purpose plainly: factory-produced, deployable fission microreactors for mission-critical systems across Earth, space, and underseas. Strip away the engineering and the goal is energy autonomy - power that does not depend on a fuel convoy, a transmission line, or a clear sky. For a base, that means it keeps running when the grid does not. For a ship or a spacecraft, it means going somewhere a battery never could.
There is a climate story folded inside the defense story, too. A reactor that can be mass-produced and dropped into critical infrastructure is, quietly, a clean-energy machine - dense carbon-free power that does not wait for the wind. Antares leads with defense because that is who pays first. The longer arc points at everyone who needs reliable power in a hard place.
Return to that lab. The Mark-0 reaching criticality was not the finish line - it was proof the assembly-line bet might hold. The roadmap from here is specific and falsifiable: electricity from an advanced reactor in 2027, first production deployments to U.S. military installations starting 2028, units rolling off a Torrance line at roughly ten a year. Plenty can slow that down. Nuclear timelines are famous for it.
But the thing that woke up in the desert was never really one reactor. It was the idea that nuclear power could be a product you order, ship, and switch on - on a base, on a ship, eventually on the way to the asteroid belt. The grid stops at the edge of the map. Antares is building the thing that keeps going.