Orbital propellant depots move closer to reality with NASA cryocoupler tests

Space travel has not one but many challenges. Chief among these is the requirement that a spacecraft carry its entire fuel supply from the moment of launch. It’s the ultimate version of over-packing for a road trip. But what if future missions could pull up to the orbiting equivalent of a fuel station and fill up in orbit instead?

To make this a reality NASA is developing and testing a specialised device called a cryocoupler to enable future deep-space exploration missions to refuel at orbital propellant depots like those discussed by SpaceX a while ago.

This specialised hardware is designed to securely connect spacecraft to orbital propellant depots. It enables the automated transfer of super-cold fluids such as liquid hydrogen and liquid oxygen chilled to hundreds of degrees below zero.

“In-orbit cryogenic refuelling 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.

“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,” Belcher added.

The process of transferring cryogenic fluid in a vacuum is highly difficult, especially when handling liquid hydrogen and liquid oxygen. These substances that must be kept at hundreds of degrees below zero Fahrenheit to remain stable.

If the seals fail or materials become brittle and shatter under the thermal shock, the entire mission is at risk.

The terrestrial fuelling hardware designed for the Artemis program’s Space Launch System rockets simply cannot function in an orbital environment. These couplers are heavy, designed to be detached during the violent shaking of a launch. In orbit, there’s a need for something lighter, cleaner, and fully automated.

Developed in partnership with L3Harris, the new cryocoupler is designed to be the orbital equivalent of a nozzle at a fuel pump. It will be able to connect two ships and create a secure, leak-proof bridge between them.

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

During recent testing at NASA’s Marshall Space Flight Center, engineers used a robotic table to simulate the real-world challenges of docking two massive, moving spacecraft in orbit.

In space, vehicles rarely align perfectly. Hence, the team deliberately created misaligned docking scenarios to demonstrate that the coupler could still adjust, securely connect, and maintain its seal even when slightly askew.

A joint NASA and L3Harris team also conducted thermal testing on the cryocoupler by running liquid nitrogen at -321°F through various connected and disconnected setups.

These tests evaluated how the hardware, seals, and fluid flow handle extreme thermal contraction and the intense temperature differences between the freezing propellant and the coupler materials.

The current tests are foundational, which prove the concept works, but are only the beginning. NASA plans to iterate on these designs to meet the specific requirements of upcoming lunar and Martian architectures.

First published on Fanatical Futurist on 26 June 2026.

311 Intelligence

What this means

Analysis by the 311 Strategic Intelligence Unit

The big shift is from carrying all your fuel at launch to filling up in orbit. NASA and L3Harris have shown a cryocoupler that can connect two spacecraft, seal even when misaligned and handle ultra-cold propellant without a spacewalk. NASA calls in-orbit cryogenic refuelling one of the toughest challenges in spaceflight. We track Off World Re-Fuelling, refuelling satellites and rockets in orbit moving from concept to first real demonstrations, as an Explore trend, and expect it to reach wide use by 2035.

What it means by sector.

• Space agencies and mission planners: NASA says these propellant transfers are essential for the missions it wants to fly. Refuelling in orbit changes how lunar and Martian missions can be designed.
• Space industry suppliers: the coupler was developed in partnership with L3Harris. We rate Privatisation of Space, private companies driving most space spending and launches, an Act now trend.
• Energy and cryogenics firms: keeping fuel cold is the hard part. We expect Zero-Boil-Off Cryogenic Storage, which stops very cold liquid fuel turning to gas, to reach wide use by 2040.

What to do now.

• If you work in the space supply chain, track NASA's next coupler designs for lunar and Martian missions.
• Look at where your skills in seals, materials or cryogenic fluids could apply to in-space refuelling.
• Plan for missions and business models that assume fuel can be bought in orbit, not only at launch.

The Starburst technologies behind this story

From the 311 Technology Starburst (first product, expected wide use and readiness):

Technology	Category	First product	Wide use	Action	TRL
Zero-Boil-Off Cryogenic Storage	Energy	2028	2040	Watch	6
Cryogenics	Energy	1895	2040	Watch	3

And the trends they feed, from the 311 Trends Starburst:

Trend	Wide use	Action
Off World Re-Fuelling	2035	Explore
Reusable Rockets	2028	Prepare
Privatisation of Space	2020	Act now

How this moves the trend

The idea of fuel stops in space has been building for almost a decade. In 2017 Elon Musk set out his plan to put a million people on Mars, and in 2022 we reported the first gas station in space. NASA's cryocoupler tests now tackle the hardest version of the problem: moving ultra-cold propellant between two spacecraft.

Go deeper with 311

• The 311 Starburst Centre: every technology and trend above, with timelines and readiness.
• 311 Vantage: ask what orbital refuelling means for your organisation and get a plain English executive brief.
• The Exponential Technology Codex and the Annual Trends Codex: the technologies and trends reshaping every industry.
• Book a briefing or keynote on the future of space for your board or leadership team.