Two unmanned commercial satellites have docked in orbit for the first time. On February 25, Northrop Grumman’s Mission Extension Vehicle-1 (MEV-1) linked up with the Intelsat 901 (IS-901) communication satellite at an altitude of 22,416 mi (36,076 km) above the Earth as part of a project to extend the service life of satellites that are running low on propellants.

The building and launching of satellites is extremely expensive, so it’s more than just frustrating when a perfectly good spacecraft has to be disposed of or abandoned simply because it has run out of the propellants needed to keep it in its proper orbit and pointed at Earth. There have been a number of solutions proposed for this problem – in this case Northrop’s MEV-1 is designed to match orbits with aging satellites, dock, and take over the job of maintaining orbit and attitude.

MEV-1 was launched on October 9, 2019, and then executed a series of orbital maneuvers to rendezvous with IS-901, 180 mi (290 km) above geosynchronous orbit. Northrop says the target communication satellite was removed from service last December after over 19 years of service and its customers transferred to other Intelsats.