Satellites aren't designed to be repaired or refueled. They get put into orbit, they last until they run out of fuel or suffer some other sort of basic malfunction, and then they just get forgotten about, left to one of any number of depressing fates: orbiting the Earth until the end of time, de-orbiting whenever they feel like it, or having a violently destructive close encounter with a fellow satellite.
But what if we could service satellites?
NASA's been working for quite a while on putting all the pieces together that would be required to go up into space, find a satellite, and pump some extra fuel into it to keep it alive.
The next-generation Canadarm was designed with this in mind, and DEXTRE has been practicing for a live robotic refueling mission, and the latest step is a teleoperated real fuel transfer test here on Earth: