Spaceflight Inc. unveils a new breed of orbital tug that’s built for far-out missions


An artist’s conception shows the Sherpa-ES orbital transfer vehicle. (Spaceflight Inc. Graphic)

When a SpaceX Falcon 9 rocket sends a robotic lander to the moon’s south pole, perhaps as early as next year, Seattle-based Spaceflight Inc. plans to make a few extra deliveries with its own piggyback spacecraft.

The mission, known as GEO Pathfinder, will represent the first in-space outing for a new type of orbital transfer vehicle called the Sherpa Escape, or Sherpa-ES.

“Orbital” might not be exactly the right term, since the craft is designed to go well beyond low Earth orbit to zoom around the moon and back, potentially deploying payloads at every step along the way.

“This mission will demonstrate our complete mission toolbox and ability to execute complex, groundbreaking and exciting missions beyond LEO,” Grant Bonin, senior vice president of business development at Spaceflight, said today in a news release.

Vehicle configuration with Sherpa

Vehicle configuration with Sherpa

GEO Pathfinder’s Sherpa-ES would serve as a secondary payload on a Falcon 9 mission that’s due to send Intuitive Machines’ Nova-C lander to the lunar south pole, with launch set for no earlier than the fourth quarter of 2022.

Smallish payloads can be attached to the Sherpa’s multiple ports for deployment in translunar orbit or low lunar orbit. It’s even possible to put satellites in geosynchronous equatorial orbit around Earth, or GEO, by a roundabout route.

“Spaceflight will utilize a launch with a creative trajectory and our best-in-class propulsion system to slingshot around the moon, allowing us to deliver payloads to GEO in an environmentally safe manner,” Bonin explained.

GEO satellites typically have to be sent to their designated locations in a multi-step, orbit-raising process that requires a heavy load of onboard propellant. Entering GEO from above, with the momentum provided during the round-the-moon trip, would reduce the need for extra fuel.

For the GEO Pathfinder mission, one of Spaceflight’s customers is GeoJump, a new company that’s dedicated to providing GEO rideshare opportunities for small satellites. One of the payloads aboard the Sherpa-ES will be Orbit Fab’s in-space refueling system. To get Orbit Fab’s payload to its destination, Sherpa-ES will perform a lunar flyby, and then head back toward Earth to settle into geosynchronous orbit.

“Offering rideshare missions to GEO is a real game-changer for the smallsat industry,” said Meagan Crawford, co-founder and managing partner at SpaceFund, which has GeoJump and Orbit Fab in its investment portfolio. “When we presented the idea of accessing GEO via rideshare with Spaceflight to our portfolio companies — as early as 2022 — the response was overwhelming. What used to be part of a long-term strategy for many of these companies is now a short-term reality.”

Spaceflight said the Sherpa-ES could be used for deep-space deployments as well.

Sherpa-ES is the latest in a line of next-generation Sherpa orbital tugs that also includes the free-flying Sherpa-FX; the Sherpa-LTE, which uses a xenon-based electric propulsion system; and the Sherpa-LTC, which uses a “green” bipropellant propulsion system. Spaceflight Inc. optimized the Sherpa-ES bipropellant propulsion system to produce higher energy for orbit-raising and inclination changes.

Sherpa-FX had its first outing as a secondary Falcon 9 payload in January. In June, another SpaceX satellite rideshare mission featured a Sherpa-LTE as well as a Sherpa-FX. The Sherpa-LTC is due to make its debut later this year.

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