NASA has announced it is developing a spacecraft that will refuel other satellites in orbit. It has awarded a $127-million contract to Space Systems Loral in California to build the spacecraft, called Restore-L.

The idea of refueling satellites has been around for a while. All satellites need propellant to maintain their orbits, which gives them a finite lifetime. But if we could refuel them in orbit, their lifetimes could be lengthened indefinitely.

This particular mission, which NASA hopes to launch by 2020, would see the spacecraft attach to NASA’s Landsat 7 Earth-observing satellite. It will use two robotic arms to attach to the satellite, before transferring fuel at the right pressure and temperature.

If the test is successful, this type of spacecraft could be used to fuel other satellites in the future. It could also be used to move satellites in orbit and clean up space debris.

This will not be the first refueling mission to be performed in orbit. Back in 2013, NASA tested its Robotic Refueling Mission (RRM) on the International Space Station (ISS), using the station’s exposed facility platform to test out the various tools that would be needed.

And in June this year, China announced it had successfully refueled one of its satellites in orbit, but they did not reveal many details on how they did it, other than saying the process was similar to how planes can be refueled in the air.

"The injection process was stable, and measurement and control were precise," the National University of Defense Technology said of the procedure, performed by the Tianyuan-1 satellite.

Whoever can crack this technology first will have access to a very lucrative market. With sophisticated satellites costing in the hundreds of millions of dollars to build and launch, being able to refuel them instead of replacing them will be an invaluable ability. Indeed, some missions – such as NASA’s upcoming Wide-Field Infrared Survey Telescope (WFIRST) – are being designed with refueling in mind.

And there are broader connotations, too. “Propellant depots”, orbiting spacecraft packed full of fuel, have often been touted as a means to explore the Solar System. Some are hoping that mining water from asteroids might be a good way to get this fuel.

All eyes will be on Restore-L in 2020, then. If successful, it could be a game-changer.