NASA just successfully demonstrated the first of three tools designed to refuel spacecraft in space, right outside of the International Space Station.

The space agency’s Robotic Refuelling Mission 3 was able to unstow a special adapter that can hold super-cold methane, oxygen or hydrogen, and insert it into a special coupler on a different fuel tank.

Future iterations of the system could one day allow us to gas up spacecraft with resources from distant worlds, such as liquid methane as fuel. And that’s a big deal, since future space explorations to far away destinations such as the Moon and Mars will rely on our ability to refuel after leaving Earth’s gravity.