NASA, L3Harris Test Cryocoupler Device Critical to Future In-Space Refueling
Automated Connector Could Enable Propellant Transfers at Orbital Depots Without Spacewalks
Engineers at NASA’s Marshall Space Flight Center have successfully tested a prototype cryocoupler — a specialized docking device designed to transfer super-cold propellants between spacecraft in Earth orbit — marking an early but significant step toward making in-space refueling a reality for deep space exploration.
“In-orbit cryogenic refueling between two spacecraft has yet to be done and remains one of the toughest engineering challenges in spaceflight.”
Travis Belcher, NASA
The testing, conducted jointly by NASA Marshall engineers and L3Harris, focused on a developmental cryocoupler that could one day allow spacecraft to connect to orbital propellant depots before pushing farther into the solar system. Think of it as the nozzle at a gas station pump — but one that must operate flawlessly at temperatures hundreds of degrees below zero in the vacuum of space.
“In-orbit cryogenic refueling between two spacecraft has yet to be done and remains one of the toughest engineering challenges in spaceflight,” said Travis Belcher, cryocoupler project manager at NASA Marshall. “These propellant transfers are essential for the kinds of missions NASA wants to fly in the future, so developing a coupler that can handle ultra-cold propellants is a critical step toward making that capability real.”
Cryogenic propellants such as liquid hydrogen and liquid oxygen must remain chilled to hundreds of degrees below zero Fahrenheit, placing extreme demands on materials, seals, and mechanisms. Unlike ground-based couplers used to fuel the Space Launch System for Artemis missions — which release during launch and require manual reconnection — the new device is fully automated and designed to attach and detach multiple times without astronaut intervention.
“The cryocouplers we’re working on can attach and detach multiple times and are fully automated, so astronauts won’t have to perform a spacewalk to transfer propellant,” Belcher said. “They’re rigorously designed to withstand space and sized for the expected tank designs.”
The test campaign included two phases. First, engineers ran liquid nitrogen at minus 321 degrees Fahrenheit through connected and disconnected coupler configurations to observe how the hardware responds to thermal contraction, fluid flow, and large temperature differentials. Second, operational tests mounted one coupler half on a robotic table capable of moving and rotating in any direction, simulating the misaligned docking that could occur when a spacecraft and orbital depot are not perfectly aligned on approach.
“These cryocouplers are very early in development, so the testing is mostly focused on basic functionality,” Belcher said. “Future test campaigns will design them for specific missions and assess them more meticulously based on that mission’s requirements.”
The work was conducted under a 2022 Announcement of Collaboration Opportunity, a NASA partnership program that provides select companies with agency expertise, facilities, hardware, and software at no cost. The Cryogenic Fluid Management Portfolio project — a cross-agency team based at NASA Marshall and NASA’s Glenn Research Center in Cleveland — oversees cryocoupler development.
More information on NASA’s cryogenic fluid management efforts is available at .