Getting things into space is expensive, and when satellites run out of fuel, they often need to be replaced. But what if we could refuel satellites and keep them perpetually in orbit?

Well, China has taken a major step towards doing just that. According to the Xinhua News Agency, they have successfully refueled a satellite in orbit for the first time using another spacecraft. This milestone opens up an array of new capabilities to the rapidly advancing China National Space Administration (CNSA).

The details of how this was done are not entirely clear, though. A comment from the National University of Defense Technology, who designed the spacecraft, references an “injection process”, adding it was stable during the process.

The spacecraft to perform this feat, Tianyuan-1, was launched on China’s Long March-7 rocket on Saturday, June 25. This launch also carried an unmanned scaled-down version of a new crew vehicle China plans to use.

Refueling in space is not entirely new, but it is not exactly a regular occurrence yet either. Several tests in the past, such as NASA’s Robotic Refueling Mission (RRM) on the International Space Station (ISS) in 2013, proved that autonomous refueling of satellites was possible. The United States Defense Advanced Research Projects Agency (DARPA) also demonstrated the technology with two spacecraft in 2007 as part of their Orbital Express project.

More recently, aerospace group United Launch Alliance (ULA) announced they wanted the upper stage of their new Vulcan rocket to act as a propellant depot, being used to refuel defunct satellites in orbit.

To maintain a permanent and large human presence in space, many see refueling satellites and other spacecraft as a key future capability. And it seems China, too, shares this vision. The nation, banned from being part of the ISS, is also pushing ahead with its new manned spacecraft and a new space station, and wants to eventually land humans on the Moon.