T
here's a moment in every space story where the hardware isn't actually the headline. This is one of those moments.
On Tuesday, 7 July, a Falcon 9 lifted off from Vandenberg Space Force Base carrying 81 payloads packed into SpaceX's Transporter-17 rideshare mission. Most of them will do what satellites usually do sit in orbit, catch sunlight, and quietly go about their business. One of them won't. Tucked inside a CubeSat called BOHR is a power source that doesn't need the sun at all.
BOHR — short for Betavoltaic Orbital High-Reliability was built by City Labs, a small Florida-based company that's spent years working on something most of the aerospace world hasn't paid much attention to: batteries powered by radioactive decay, shrunk down to the size of a coin.
The satellite itself still leans on ordinary solar panels to run its bus the boring but essential plumbing that keeps any spacecraft alive. But bolted onto it is a separate, experimental payload: City Labs' proprietary NanoTritium betavoltaic system, flying in space for the very first time.
Here's the trick. Tritium, a radioactive form of hydrogen, decays and throws off beta particles as it does. Point those particles at a semiconductor, and you get a slow, steady trickle of electricity no sunlight, no moving parts, no combustion, nothing to wear out. It's a cousin of the radioisotope thermoelectric generators that have powered NASA's Voyager probes and the Perseverance rover for decades, except those rely on the heat thrown off by decaying plutonium. NanoTritium skips the heat step entirely and converts the particles directly into current.
The output is tiny we're talking nanowatts to microwatts, nowhere close to what a smartphone sips. But the trade-off is durability. A betavoltaic cell like this can theoretically keep running for decades, in total darkness, in extreme cold, without a single recharge.
It's a fair question. Why build an entire mission around a battery that can barely light an LED?
Because sunlight, it turns out, is not everywhere. Solar panels are useless inside a permanently shadowed lunar crater. They're next to useless on a multi-year voyage into deep space, or on a sensor network meant to sit untouched on an asteroid for a decade. NASA's own Artemis program is pushing back toward the Moon, and mission planners are increasingly asking the same question: what powers the instruments that have to keep working when the sun simply isn't an option?
City Labs thinks its answer is tritium. Not a reactor, not a fission core just a quiet, low-radiation battery engineered to be shipped, handled, and bolted onto a satellite the same way any ordinary component would be.
Here's the part that's easy to miss under the "nuclear satellite" headline: BOHR's biggest achievement may not be technical at all. It's regulatory.
Launching anything containing radioactive material in the United States means clearing a process built under National Security Presidential Memorandum-20, a framework put in place back in 2019 specifically for space nuclear systems. Sandia National Laboratories reviewed the safety case, and the FAA issued its formal payload authorisation on 30 September 2025 making BOHR the first commercial mission ever to make it through that pathway from start to finish.
City Labs CEO Peter Cabauy has been fairly blunt about what he thinks the win really is. Nuclear power in space isn't new governments have flown it for decades. What's new, he told one outlet, is dragging it out of the government-only lane and proving it can survive a commercial launch and a commercial approval process.
BOHR won't power a lunar base. Not yet, and probably not for a long while its current output is far too modest for that. What it will do, over the coming weeks and months, is sit in orbit while engineers watch how the NanoTritium cell behaves: how it holds up to launch stress, temperature swings, and the general unpleasantness of space.
If it performs the way City Labs hopes, this modest CubeSat becomes a reference point proof that a privately built nuclear micropower source can be designed, approved, launched, and operated without a government agency running the whole show. Funded in part through a U.S. Department of Defense contract, and with City Labs already sitting on a fresh DARPA award to push the technology further, BOHR looks less like a one-off experiment and more like an opening move.
Small satellite. Small battery. Potentially, a fairly large shift in how future spacecraft stay alive in the dark.
