An artist’s conception shows Spaceflight’s Sherpa-FX in orbit. (Spaceflight Illustration)

Seattle-based Spaceflight Inc. today unveiled two new options for its Sherpa orbital transfer vehicle — one that uses an environmentally friendly chemical thruster system to help get small satellites where they need to go, and another that’s powered by an electric propulsion system.

Such options add propulsive capability to the standard Sherpa-FX model, which is due to make its first flight as a secondary payload for a SpaceX Falcon 9 rocket launch by as early as December.

For years, Spaceflight has served as a broker and concierge for other people’s payloads — basically bundling small satellites for launch on rockets ranging from the Falcon 9 to Rocket Lab’s Electron and India’s PSLV.

The company hit a significant milestone in 2018 when it arranged for the launch of 64 satellites on a single Falcon 9. During that mission, a pair of free-flying spacecraft served as deployment platforms.

That blazed a trail for the Sherpa program, and the effort got an extra boost this year after Spaceflight Inc.’s acquisition by Japan’s Mitsui & Co.

“Really, the next step in building out this cislunar space transportation company that we care to become is the Sherpa program,” Grant Bonin, Spaceflight’s senior vice president of business development, told GeekWire. “Sherpa was an early vision of the company, but we really revived it this year.”

The heart of the Sherpa spacecraft is a hexagonal chassis to which a variety of satellites and satellite deployers can be attached. There’s also a telemetry system that can relay satellite data down to the ground via GlobalStar.

During the upcoming flight, which Spaceflight calls the SXRS-3 mission, the Sherpa-FX will be sent out from the Falcon 9’s second stage to fly freely in its own orbit for satellite deployment.

Spaceflight plans to put more than a dozen spacecraft into orbit from its first Sherpa-FX. There’ll also be piggyback payloads that stay on board, including capsules that contain funerary ashes for Celestis’ memorial spaceflight program.

Bonin noted that the Sherpa-FX is merely the basic model.

“The flashy parts of this are that, in addition to being a mothership for small spacecraft, now we can start to incorporate propulsion,” Bonin said. “And not just middle-of-the-road propulsion … but propulsion systems that really attack the key use cases that we see being expressed by our customers.”

The Sherpa-LTC and Sherpa-LTE round out Spaceflight’s product line for orbital transfer vehicles.

Sherpa-LTC’s high-thrust green propulsion subsystem, provided by Benchmark Space Systems, makes use of chemical propellants to offer a “go-fast” solution for operators who need their satellites deployed into a specified orbit within a matter of minutes, Bonin said. The first Sherpa-LTC is due to fly in the second half of 2021.

In contrast, Sherpa-LTE’s electric propulsion system takes advantage of radiation-hardened Hall thrusters developed by Apollo Fusion. Fueled by xenon propellant, the system can send payloads to different orbital planes, geosynchronous orbit or even beyond Earth orbit. “We call that the go-far solution,” Bonin said.

Sherpa-LTE is due to make its first flight in mid-2021.

Sherpa variants
Spaceflight offers three options for its Sherpa orbital transfer vehicle. Sherpa-FX doesn’t use a propulsion system; Sherpa-LTC has a conventional chemical propulsion system; and Sherpa-LTE has an electric propulsion system (Spaceflight Illustration)

Jeff Roberts, Spaceflight’s senior director of mission management, said his company aims to fly about six Sherpa vehicles per year, including at least one of each variant. “We don’t know how many of each,” he said. “That’s actually one of the great things about this: We don’t need to know this far out, because it’s the same chassis.”

Roberts said the beauty of the Sherpa system is that components can be switched around quickly to accommodate the different propulsion systems. And if launch schedules change, the entire spacecraft is easily transferable from one rocket to another. He compared the Sherpa’s versatility to the functions of a Swiss Army knife — or a Gerber multi-tool, for those too young to remember Swiss Army knives.

“Our goal is to get our customers’ spacecraft delivered to orbit exactly where and when they want it, all the way to their final destination — that last leg of the journey,” Bonin said in a news release. “Our new Sherpa OTVs enable us to provide that in-space delivery service while keeping costs low and timelines short.”

Spaceflight isn’t the only company betting on orbital transfer vehicles. Momentus Space made a splash in March when it announced a plan to offer such services on six SpaceX satellite rideshare missions. Firefly Aerospace, D-Orbit and Exolaunch are also moving into the market. But with more than 300 satellite deployments under its belt, Spaceflight is counting on Sherpa to keep blazing the trail.

“We are excited to build on our 10 years of launch experience learnings to develop these new advanced vehicles, which will provide even more flexible launch options and customized orbital delivery for our customers,” said Curt Blake, Spaceflight’s president and CEO.

Like what you're reading? Subscribe to GeekWire's free newsletters to catch every headline

Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.