Halen Mattison

Most space founders sell a rocket and a launch date. Halen Mattison sells something quieter: the ability to move once you get there, and the fuel to keep doing it. His company, General Galactic, calls the goal a railroad to Mars. The trains do not exist yet. He is laying track.

Mattison is the co-founder and CEO of General Galactic, an El Segundo company he started in 2023 with Luke Neise. Before that he was an engineer at SpaceX, on a team working on propellant generation for Starship - the systems meant to make rocket fuel on the surface of Mars rather than haul it there. It is one of the least glamorous problems in spaceflight and one of the most decisive. A ship that cannot refuel is a one-way ship.

The idea that became General Galactic started inside SpaceX. Mattison kept circling the same question: how do you actually make fuel out of what is already on Mars? When the company decided the timeline was too long to pursue, he did the thing that sounds reckless until it works. He left, enrolled at Stanford for graduate school, and went looking for a co-founder. He found Neise there. Both graduated in 2022. Within a year they had a company.

It is worth sitting with how unusual that move is. SpaceX is, for a certain kind of engineer, the destination - the hardest, most coveted room in aerospace. Mattison was inside it, working on exactly the Mars-relevant problem he cared most about, and he walked out the door because the calendar did not agree with him. Not a falling-out, not a better offer. A disagreement about timelines. He believed the propellant infrastructure that unlocks everything between here and Mars needed to be started now, and if the place best positioned to build it was not ready, he would rather be the one who started early.

What they noticed at Stanford reframed the whole venture. The chemistry that makes methane from carbon dioxide on Mars works just as well on Earth - and on Earth there is a paying customer waiting. So the first version of General Galactic was, in plain terms, a climate-tech company: capture CO2 from the air, split water into hydrogen with renewable electricity, combine the two into methane. A pilot system was soon producing roughly 2,000 liters of the stuff a day.

That is a Seth Godin kind of sentence: not cleaner than drilling, not greener than drilling - cheaper. The pitch was never charity. It was that the incumbent technology, pulling hydrocarbons out of the ground, could be beaten on its own terms. The company raised $1.9 million in pre-seed money in 2023 from BoxGroup and Refactor, emerged from stealth in 2024, and followed with an $8 million seed round co-led by Harpoon Ventures and Refactor Capital. Climate Capital, Pathbreaker, Plug and Play, Seraphim and others joined.

To make the economics work, Mattison did something founders are usually warned against: he insisted on owning the supply chain. Off-the-shelf parts came out; in-house components went in. "Being able to own our supply chains, to be able to fully control all of the parameters," he has said, is what unlocks engineering elegance. It is slower and harder up front. It is also the only way the numbers eventually close.

Then the company sharpened its aim back toward orbit. The newer face of General Galactic is Genesis - a propulsion platform that runs on water and nothing else. The claim is striking enough to sound like marketing until you read the spec sheet: hydrazine-level thrust, xenon-level efficiency, from the safest, cheapest and most abundant propellant in the solar system. Genesis is built to act as both a chemical engine, for high thrust when you need to move fast, and an electric engine, for high efficiency when you need to move far. One spacecraft, two personalities, picked on demand.

Why does that matter? Because the bottleneck in space is not the launch anymore. Commoditized rockets have made getting to orbit almost routine. What is still hard - still expensive, still slow - is maneuvering once you arrive. Mattison's contention is that modern spacecraft engines often underperform the first-generation hardware of the original space race. General Galactic designs, analyzes, tests and manufactures its engines under one roof in El Segundo, and says it has already demonstrated working prototypes of both the high-thrust and high-efficiency modes.

The grand version of the plan is unapologetically large. General Galactic describes its job as building the thru-line between three things that usually live in separate companies: spacecraft mobility, orbital infrastructure, and in-situ resource utilization - the practice of making what you need from materials already in space. Stitch those together, the argument goes, and moving beyond Earth stops being a heroic one-off and becomes ordinary. A railroad, not an expedition.

The phrasing is borrowed honestly. The company points to Kim Stanley Robinson's 1992 novel Red Mars, which imagined the unglamorous infrastructure of settling another planet long before it was fashionable. Mattison has been candid that he is building toward something more like a logistics utility than a flag-planting mission - General Galactic, in his framing, as the galaxy's energy and logistics company. The work also reaches back to Earth and out to government: he has contributed to space initiatives for both the Department of Defense and NASA, and the company's high-agility satellite work is pitched squarely at cutting the cost of space logistics and defense operations.

There is a refreshing lack of mysticism in how he talks about all this. The electrolysis cells that split water for Genesis are the same building blocks he imagines as propellant factories on the Moon and Mars. The methane reactor that beats drilling on cost is the same chemistry that would refuel a ship on the Martian surface. Earth applications fund the technology; the technology eventually leaves Earth. It is one bet, wearing two coats.

He is also unusually willing to talk about things blowing up. Mattison has spoken publicly about why discussing rocket-engine failures openly - including specific combustion-chamber failures in NASA research - is essential rather than embarrassing. In an industry that loves a triumphant launch reel, a founder who wants to discuss the rapid unscheduled disassembly is a useful kind of strange.

The company's motto, stamped on its own about page, is Esse Quam Videri - to be rather than to seem. For a startup in a sector full of rendered spacecraft that never fly, it reads less like a slogan and more like a dare. Build the real thing. Test the real thing. Let it fail in the open if it has to. Mattison's whole arc - quitting the most famous rocket company on Earth because its timeline was too short for his idea - is the motto in motion. He would rather be early and right than safe and late.

None of it is finished. The trains, to return to his own metaphor, are not running. But the track is being laid in a warehouse in El Segundo, one water-fueled engine at a time, by someone who decided that the most important part of the future was the part nobody else wanted to build.

The location is not an accident. El Segundo, a small grid of streets tucked under the flight path of LAX, has quietly become the densest square mile of hard-tech aerospace in the country. SpaceX is up the road. So is a generation of companies founded by its alumni. General Galactic sits on Sierra Street, a few blocks from the kind of machine shops and test stands that a propulsion startup needs within walking distance. When you are designing, analyzing, testing and building engines in-house, geography is not a detail - it is the difference between iterating in days and iterating in months.

It also explains the company's appetite for doing things the hard way. Mattison and Neise could have bolted together a demonstrator from purchased subsystems and shown a video. Instead they chose vertical integration: build the electrolysis cells, build the reactor, build the engine, own the parameters. In a region full of people who have watched that exact approach succeed at scale, it is less a contrarian gamble than a learned instinct. The founders are alumni of what they call transformative space companies - Mattison from SpaceX, where the lesson was that controlling your own hardware is what lets you move fast.

The team around them is small and deliberately so. Neise, the chief technology officer, runs the engineering. A founding engineer and a business-development lead round out the early roster. For a company describing ambitions on the scale of solar-system logistics, the headcount is almost comically modest - a reminder that at this stage the product is not a fleet of spacecraft but a working engine and a credible plan. The plan is what the investors bought.

And the plan keeps the two halves of the company honest with each other. The Earth-bound methane business is not a distraction from the space mission; it is the proving ground. Every improvement to the electrolysis stack that makes terrestrial methane cheaper is an improvement to the propellant factory that would one day sit on the Moon or Mars. Every lesson in mass-manufacturing a reactor on Earth is a lesson in mass-manufacturing the infrastructure of the second space age. Mattison has been clear that hydrocarbons for transportation are somewhere on the roadmap too - asked directly, he offered only a two-word answer: stay tuned.

That restraint is its own kind of signal. A founder with a railroad-to-Mars thesis could fill an hour with speculation. Mattison tends instead to point at the thing in front of him - the reactor running today, the prototype that fired last week, the spec he can defend. The grand vision is real, and he will tell you about it. But he would rather you judge him by what is bolted to the test stand. To be rather than to seem.