Here is a fact about rockets that sounds made up but isn't: for about sixty years, one of the most common ways to nudge a satellite around in orbit has been to squirt hydrazine at it. Hydrazine is a propellant that is efficient, reliable, and also so toxic that the people who handle it wear what are essentially hazmat spacesuits. It is a substance whose main selling point is that it works and whose main drawback is that it is trying to kill you. This is the industry General Galactic looked at and said: what if, instead, we used water.
General Galactic is a deep-tech startup founded in 2023 and based in El Segundo, California, the dense little aerospace town south of LAX that people have started calling the “Space Beach.” The company was started by Halen Mattison and Luke Neise, two engineers who met doing master's degrees at Stanford and then went to work at, respectively, SpaceX and Varda Space Industries - which are the sorts of companies you leave only if you have decided you have a better idea. Their better idea is water.
The pitch, roughly, is this. You take water. You run electricity through it - electrolysis, the thing you probably did in a middle-school science class - and you split it into hydrogen and oxygen. Now you have two of the most useful gases in rocketry sitting in your tank, and you can do one of two things with them. You can recombine them in a combustion chamber and get a hot, high-thrust chemical burn, the kind you want when you need to move fast. Or you can feed the oxygen into an electric thruster, turn it into plasma, and get a gentle, extremely efficient push that you can sustain for a very long time. General Galactic's engine, called Genesis, is designed to do both from the same tank. They call it multimode, which is engineering-speak for “you don't have to choose.”
Why water is the interesting boring answer
The reason to care about the fuel and not just the engine is logistics, which is a word that does more work in the space industry than any rocket does. Every kilogram of propellant a spacecraft uses had to be lifted off Earth at enormous expense, and once it's gone, it's gone. But water is different in one crucial way: you can find it elsewhere. There is ice on the Moon. There is ice on Mars. If your entire propulsion system runs on water, then in principle you can refuel far from home - you don't have to ship the fuel, you ship the machine that makes the fuel and let it drink from a local supply.
This is where General Galactic's ambitions get large in a way that is either visionary or slightly unhinged, depending on your mood. The company describes itself, without much hedging, as wanting to become “the galaxy's energy and logistics company.” The plan is to deploy electrolysis-based propellant factories - first in orbit, then on the lunar surface, then on Mars - so that spacecraft can top up wherever they happen to be. Neise has described the goal as building “a railroad to Mars,” and the analogy is apt: railroads didn't win because the trains were fast, they won because someone built the stations and the water towers in between.
The part where they also make natural gas
Now, here is the twist that makes General Galactic more interesting than a pure space-propulsion company, and also slightly harder to describe at a dinner party. The same core technology - an electrolysis reactor that combines water, electricity, and carbon - can be pointed at Earth. Feed it renewable electricity and waste CO2 from a factory, and it produces fossil-free natural gas, with oxygen as a byproduct. A pilot system the company has described makes on the order of 2,000 liters of methane a day.
Mattison's argument for this is worth quoting, because it's a genuinely contrarian take on the energy transition. “So much of the green transition has been styled in a way of, we need to move away from the past and replace it with something new and clean,” he has said. “For big things that need to go far - ships, planes, rockets - that's not going to work.” The idea is that you can't just tell a container ship to become an electric vehicle. What you can do is make a clean fuel that the existing engine already knows how to burn. It is a less romantic story than ripping everything out and starting over, and it might be a more useful one.
Trinity, or: put up or shut up
The thing about water-electrolysis propulsion is that engineers have chased it for decades and it has stubbornly refused to become routine. Steam is hot and corrosive; electrolysis hardware is heavy; and splitting water costs energy you have to carry. Skepticism here is not rudeness, it's just physics being physics. Which is why the company's near-term plan is a demonstration mission, called Trinity: a satellite of roughly 500 kilograms that carries only water for propellant, flying as a rideshare payload on a SpaceX Falcon 9. If it works in orbit, the whole grand story gets a foothold in reality. If it doesn't, well, that's what demonstration missions are for.
There's a Latin motto on the company's site - Esse Quam Videri, “to be rather than to seem” - which in an industry famous for glossy renderings of things that don't exist yet reads as a small, pointed bet on substance. General Galactic has raised about $10 million, employs around fifteen people, and is trying to do something that would rearrange the economics of moving through space. Whether it works is genuinely unknown. But the question it's asking - why are we still shipping fuel to space when the universe is full of water? - is a good one, and good questions are how frontiers usually start.