This space company is betting its future on a propellant available everywhere - Ars Technica

Robert, Ryan, and Kirby Carlisle are three engineers who worked at SpaceX during the Falcon 9 era, seeing the revolution in the global launch industry from the inside.

The brothers launched rockets, refurbished rockets, and sold rockets. But when it came time for them to leave SpaceX and start their own space company—a lifetime dream for the Carlisle brothers—they chose not to build rockets. Rather, they focused on spacecraft.

In late 2022, the three Carlisles founded Argo Space to build infrastructure in space. Their vision was not just in-space transportation but also removing the need to use propellants from Earth to move around the heavens. They chose water, which is potentially harvestable on the Moon and found all over the Solar System, as a means of propulsion.

“We based the company on water,” Robert Carlisle said in an interview.

The availability of water is key to the company’s vision for building a transportation network between low-Earth orbit, geostationary orbit, and the Moon. This would open up a large number of affordable logistics options, such as satellite resupply, refueling, repair, redeployments, and more. And in the company’s vision, water is not just a propellant; it’s also a coolant and radiation shield. Much of the spacecraft, including its thrusters to the avionics, is cooled by water. This helps increase the propellant mass fraction of the spacecraft, meaning more mass is devoted to propellant, allowing the vehicle to go farther and do more things.

“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,” Robert Carlisle said.

When even former SpaceXers can’t find a Falcon 9

Argo Space flew its first demonstration mission, dubbed Navigator, in July on a Falcon 9 rideshare. The company successfully made contact with the spacecraft, but one of its two rollout solar arrays failed to deploy. Controllers spent about half a day troubleshooting the issue and gathering data on the spacecraft’s health. Unfortunately, however, the spacecraft remained power-negative, draining its battery. There was not enough energy to test the propulsion system.

“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. “So, you know, obviously that’s going to be a key goal on these next two missions.”

What are the next two missions? The company’s next-generation spacecraft, Chiron, is intended to pack high performance into a small, roughly 200-kg package.

The company plans two Chiron missions in 2027, both flying payloads for an undisclosed national security customer. The first mission is bound for low-Earth orbit, and the second to a geostationary transfer orbit. The goal across the two flights is to demonstrate Chiron’s propulsion system, including its ability to maneuver between different orbital environments.

It’s notable that the Carlisles spent much of their working lives at SpaceX to open up access to space with the Falcon 9 rocket, but neither of Argo’s next two missions will fly on a SpaceX vehicle. That’s because the company is pulling back on the commercial availability of the workhorse launch vehicle.

So Argo’s first Chiron mission is flying on an undisclosed new commercial rocket, definitely a calculated risk. And the second is going on an unspecified government-furnished launch vehicle. Argo Space probably would have preferred a rideshare on the Falcon 9 for its first Chiron mission, but one was not available within its schedule.

“We don’t want to be waiting around for another year and a half, two years plus to go get that ride,” Robert Carlisle said. “Right now you’ve got to get on a wait list, and it’s far out. There’s not launches available for sale.”

How does water actually work as a propellant?

Argo says it can achieve more than 2 km/s of delta-v in a roughly 200 kg spacecraft. That’s a lot of capability for a small vehicle, allowing it to do things like raise a circular orbit at about 400 km above the Earth’s surface to more than 5,000 km. It’s also equivalent to several decades of station-keeping in geostationary orbit.