Future deep space missions may need to refuel in orbit before they can head to their final destinations. NASA has been working on in-orbit refueling solutions for years, and one of its latest efforts is testing a “cryocoupler” developed by American tech company L3Harris. You can think of the cryocoupler as the nozzle of a gas pump, which is needed so it can fit a car’s fuel tank. Cryocouplers will allow spacecraft to link to orbiting gas stations, so they can fill up before they leave the vicinity of our planet. 

“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’s Marshall Space Flight Center in Huntsville, Alabama. Effective cryocouplers will have to be able to facilitate the transfer of extremely cold fluid, such as liquid hydrogen and liquid oxygen, without leaking. And since these propellants have to stay chilled at hundreds of degrees below Fahrenheit, the device will need to have the proper materials and strong seals. They (obviously) cannot be manually operated, as well.

“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 added. “They’re rigorously designed to withstand space and sized for the expected tank designs.”

To test L3Harris’ cryocoupler, Belcher’s team ran liquid nitrogen at negative 321 degrees Fahrenheit through several connected and disconnected configurations. Those tests provided the team with data on how the device reacts to significant temperature differences. They also put the coupler through operational tests, such as simulations of misaligned dockings, as the device was designed to accommodate some degree of misalignment. 

It’s early days for L3Harris’ cryocoupler, so these tests are pretty basic. Belcher says future tests will be designed for specific missions, so the coupler can be assessed according to those missions’ requirements. For now, you can watch part of the test below.

For @NASA’s next generation of deep space exploration missions, spacecraft may need to refuel in Earth orbit before pushing farther into the solar system.

Engineers from #NASAMarshall and L3Harris are testing a technology vital for in-orbit refueling: https://t.co/oeqGBtvzpj pic.twitter.com/4w6HErAIAq

— NASA Marshall (@NASA_Marshall) June 26, 2026