Argo Space Bets Future on Water as Spacecraft Propellant

Argo Space is building its spacecraft business around water instead of conventional rocket propellant, according to Ars Technica. The company, founded in late 2022 by brothers Robert, Ryan and Kirby Carlisle, aims to use water as fuel, coolant and radiation shield for a fleet of in-space transport vehicles.

Who runs Argo Space?

The three Carlisle brothers worked at SpaceX during the Falcon 9 era, where they launched, refurbished and sold rockets, Ars Technica reports. When they left to start their own company, they chose not to build rockets. They focused on spacecraft that move cargo and satellites once they reach orbit.

Why build around water?

Water is harvestable on the Moon and present across the Solar System, making it a propellant source that does not have to be launched from Earth every time, according to the outlet.

"We based the company on water," Robert Carlisle said.

Argo Space's design uses water for more than thrust. The outlet reports that water also cools much of the spacecraft, from thrusters to avionics, which raises the propellant mass fraction of the vehicle — more of its total mass can be devoted to fuel rather than structure, letting it travel farther and do more maneuvers.

Carlisle told Ars Technica the long-term plan is to turn that into a business case for lunar mining. "In the long run, this water-based transportation will give us a commercial incentive, a profit motive to go harvest it from the Moon's shallower gravity well," he said.

What happened on Argo's first demo flight?

Argo flew its first demonstration spacecraft, Navigator, in July on a Falcon 9 rideshare mission, according to Ars Technica. Controllers made contact with the craft, but one of its two rollout solar arrays failed to deploy. Ground teams spent roughly half a day troubleshooting and gathering health data, but the spacecraft stayed power-negative and its battery drained before the propulsion system could be tested.

"We did get to validate the flight software, the ground software, the core avionics, the structures, and everything up to flight qualification, but no propulsion," Robert Carlisle said, per the outlet.

What are Argo's next missions?

Argo Space's next-generation spacecraft, called Chiron, is designed to fit high performance into a roughly 200-kilogram package, Ars Technica reports. The company has two Chiron missions planned for 2027, both carrying payloads for an undisclosed national security customer.

The first Chiron mission targets low-Earth orbit. The second heads to a geostationary transfer orbit. Across both flights, the stated goal is to demonstrate Chiron's water-based propulsion system in flight, including its ability to maneuver, after the Navigator mission never got the chance to test it.

What is Argo's broader business plan?

The company's pitch extends beyond any single spacecraft. Argo Space envisions a transportation network linking low-Earth orbit, geostationary orbit and the Moon, opening the door to lower-cost satellite resupply, refueling, repair and redeployment services, according to Ars Technica. Whether that network materializes will depend on whether Chiron succeeds where Navigator fell short: actually firing its water-based thrusters in space.

The full report, including additional detail on Argo Space's engineering choices and mission timeline, is available from Ars Technica.