Stoke Space hops its upper stage, leaping toward a fully reusable rocket

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Stoke Space's Hopper 2 takes to the skies on Sunday in Moses Lake, Washington.

At an airfield in Eastern Washington on Sunday, the small launch company Stoke Space flew its upper stage for the first time.

The flight was, admittedly, rather modest. The second-stage rocket only ascended to about 30 feet (9 meters) and traveled just several feet down range. The entire flight was over in 15 seconds.

And yet this was a momentous step for Stoke Space, which is less than 4 years old and has only about 90 employees. The test successfully demonstrated the performance of the company’s oxygen-hydrogen engine, which is based on a ring of 30 thrusters; the ability to throttle this engine and its thrust vector control system; as well as the vehicle’s avionics, software, and ground systems.

“It was a tiny little bunny hop,” said Stoke Space co-founder Andy Lapsa in an interview with Ars. “But it was the icing on the cake. It was great to get that notch in our belt.”

A novel second stage

This hopper vehicle lacked a payload fairing, but it otherwise is similar to the planned upper stage of Stoke’s rocket, measuring 13 feet (4 meters) in diameter and standing 20 feet (6 meters) tall. This was the second prototype hopper built by Stoke. The first one was lost in the spring during testing.

Stoke Space intends for its second stage to fly back to Earth and land vertically after a launch. Accordingly, the upper stage has a novel engine design—a ring of 30 thrusters instead of a single engine with a nozzle—to make sure the vehicle can fly safely through both the vacuum of space as well as the thicker atmosphere near the surface of the Earth. This stage was the more complex and novel element of the rocket’s design, so it’s where Lapsa and the small Stoke team began their efforts.

After achieving all of their technical milestones with the upper stage, Lapsa said the company will now turn its focus toward developing a more traditional first stage of its as-yet-unnamed rocket. Lapsa said Stoke engineers are already developing a full-flow, staged combustion rocket engine for the first stage. Seven of them will power the booster. Component testing is already underway for these engines.

Lapsa said the company is working toward a 2025 debut of Stoke’s rocket, although he added that “there are some interesting opportunities out there to fly sooner than that.”

From here to orbit

Stoke Space has been allocated the use of Launch Complex 14 at Cape Canaveral Space Force Station in Florida. This historic pad is where John Glenn launched from in 1962, becoming the first American to reach orbit. There is a significant amount of work needed to refurbish the site, as its most recent launch came in 1966.

The company is an interesting one to watch, because through the end of 2020 it consisted of just Lapsa and his co-founder, Tom Feldman. They were both propulsion engineers at Blue Origin and believed the company was not moving fast enough. In the last three years, they and their team have moved quickly indeed to reach the point at which they have an operational second stage capable of a short flight.

“I love Jeff’s vision for space,” Lapsa said in an interview with Ars last year. “I worked closely with him for a while on different projects, and I’m basically 100 percent on board with the vision. Beyond that, I think I would just say that I will let their history of execution speak for itself, and I thought we could move faster.”

There is yet a long way to go from this hop to an orbital flight for a small rocket designed to carry a little more than 1.5 metric tons to low-Earth orbit. But it does seem likely that, assuming SpaceX can get its Starship vehicle operational, Stoke Space has an opportunity to become the second company to build a fully reusable rocket. And no company has started out with that singular goal for its very first rocket.

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