The US Space Force has outlined plans to test a new method of keeping satellites in orbit for longer: mid-orbit refueling. The tests will take place in 2026 and 2027 and will involve proposed solutions from major defense contractors like Northrop Grumman and newer orbital technology companies like Astroscale and Orbit Fab.
Even as low-earth-orbit launch costs come down with the introduction and advancement of new launch vehicle technologies, there’s no denying that getting anything into space is still a very expensive and occasionally dangerous endeavor. One method proposed to keep satellites and other space hardware flying for longer is to refuel them in flight. The program to explore this was originally funded in 2022 and is now set to run several tests under the Tetra-5 and Tetra-6 mission branding over the next few years, as per SpaceNews.
The first mission, Tetra-5, is scheduled for sometime in 2026 and will deploy two small satellites from Orbit Fab, each fitted with its unique Rapidly Attachable Fluid Transfer Interface (RAFTI). This specially designed valve will enable the transfer of fuel from one satellite to another while in orbit.
The Orbit Fab refuelling nozzle could become a standard for a range of spacecraft.
Credit: Orbit Fab
The first satellite will rendezvous with an Orbit Fab propellant depot to perform the fuel transfer, while the second will try to dock with an Astroscale propellant shuttlecraft. In each case, Orbit Fab’s satellites will attempt to refuel from the propellant storage craft, showcasing the capability to transfer fuel effectively from one craft to another while circumventing the Earth at thousands of miles per hour.
Tetra-6 is the follow-up mission currently slated for some time in 2027. It will test Northrop Grumman’s Passive Refueling Module (PRM) using a small satellite that will attempt to dock with Northrop Grumman’s own Rapid On-Orbit Space Technology Evaluation Ring, or more catchily, ROOSTER-5. That satellite acts as a form of fuel tanker, which would sit in a geosynchronous and provide fuel to satellites holding orbits much farther from Earth’s surface.
The Space Force has approved the approach from each company, suggesting they should all work for commercial refueling solutions. However, it has yet to lend its backing to any one design, suggesting it is waiting for these test runs to provide further government contracts to encourage their development and adoption. The idea is to develop commercial solutions that can operate profitable ventures in the space logistics industry longterm, without the need for government subsidies or intervention.
In-space refueling measures could also be used for future long-distance missions, as it could spread the cost of lifting the required fuel into orbit over several launches rather than forcing everything to be sent up in a single go.