Argonaut
Argo's water-powered transfer vehicle that picks up payloads in low orbit and hauls them to geostationary orbit or lunar orbit.
Why it matters
Launching only to low orbit is the cheapest ride. A refuelable tug that does the long haul could cut the cost of reaching GEO and the Moon, and Argo's first booked lunar job is ispace's Alpine relay satellite.
How the technology works
Argonaut carries a large tank of water and splits it into hydrogen and oxygen to make high-thrust propellant. It is built to be refueled on orbit so one vehicle can fly many trips.
A demonstration Argonaut launched in July 2026; it separated, communicated and was commanded, but the mission ended early.