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LEO Knight artwork
An artist’s conception shows the LEO Knight space robot at right, working on a small satellite in orbit. (Tethers Unlimited Illustration)

Bothell, Wash.-based Tethers Unlimited works on space technologies ranging from radios to robotic arms, but the company is planning to put all those pieces together to create a space robot called “LEO Knight.”

“LEO Knight is a microsat-class system intended to support in-space servicing, in-space assembly and in-space manufacturing activities,” Tethers Unlimited CEO Robert Hoyt told GeekWire in an email. “Likely timeline for the first mission is 3-4 years from now.”

The robot takes advantage of technologies that Tethers Unlimited has been developing under the terms of NASA and Defense Department contracts, plus some internally funded projects. Hoyt ticked off the list:

  • Hydros thruster: Hydros uses electrolysis to split water into hydrogen and oxygen gas, which can then be burned as rocket propellants. The concept meshes well with the idea of extracting water ice from the moon or near-Earth asteroids for spacecraft refueling. Three Hydros-M flight units already have been delivered to Millennium Space Systems, and Hoyt said a Hydros-C module is due for launch on the PTD-1 CubeSat mission in December.
  • Kraken robotic arm: Tethers Unlimited has been working under a NASA contract to integrate the robotic arm into an experimental payload called Mantis, to enable teleoperation of experiments on the International Space Station. (Seattle-based Olis Robotics is a partner on Tethers Unlimited’s Mantis and FabLab projects.) Tethers Unlimited also has an Air Force contract to work on Kraken-X, a version of the arm that could be used for satellite servicing and in-space assembly.
  • Dactylus servicing interface: This consists of a servicing port that would be integrated onto spacecraft when they’re built, plus a compatible KRAKEN attachment that provides docking capabilities and integrates standard electrical connectors.
  • SWIFT software-defined radios: Tethers Unlimited’s radio systems can provide space-to-ground communications links for telemetry, tracking and control, plus high-bandwidth data links for monitoring complex robotic operations. “We now have over a half-dozen SWIFT radios on orbit … and they are operating well,” Hoyt said.

NASA and the Pentagon’s Defense Advanced Research Projects Agency, or DARPA, have their own projects to develop in-space servicing spacecraft, known respectively as Restore-L and Robotic Servicing of Geosynchronous Satellites.

“While we are strong supporters (and someday hopefully customers) of Restore-L and RSGS, those systems are too large and expensive to be optimal for providing services to the rapidly growing small-satellite market,” Hoyt wrote in his email.

LEO Knight (with “LEO” standing for low Earth orbit) would be optimized for refueling small LEO satellites, removing derelict satellites from constellation altitudes, assembling work platforms in space, and delivering payloads to those platforms.

Hoyt said Tethers Unlimited is “most interested in owning and operating the satellites as an in-space service, but we’d certainly consider selling the systems to commercial or government clients if they feel more comfortable operating them themselves.”

The first operational use for LEO Knight would probably be for refueling a fleet of small satellites built on Tethers Unlimited’s HyperBus 12U modular CubeSat platform. For what it’s worth, 12U describes a satellite size that’s on the order of 8 by 8 by 12 inches, or roughly the size of a toolbox.

“We are not yet ready to discuss their mission publicly, but what I can say is that the LEO Knight refueling service will enable those small satellites to perform a new class of high-value missions that are not feasible or affordable using heritage satellite architectures,” Hoyt said.

Is Tethers Unlimited looking at national security applications as well as commercial applications?

“If we were, I’m sure I wouldn’t be able to discuss it,” Hoyt said. “But we’re most interested in establishing a commercial operation, as we see an in-space refueling service as a keystone to bootstrapping a water-based off-world economy.”

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