Currently, every satellite put into orbit will become interstellar refuse, destined to be tracked (and perhaps dismantled) by DARPA or eventually disposed of by gigantic lasers (maybe). Naturally, NASA's not so keen on such waste, and it knows that many satellites' shelf lives can be extended with the addition of more fuel. Enter the Remote Robotic Oxidizer Transfer Test (RROxiTT), a project aimed at building a robot platform capable of refilling satellite fuel tanks both on earth and in space.
To make it happen, scientists are working out a method for delivering highly combustible oxidizer (aka a chemical used to ignite rocket fuel) to satellites that were not designed to be serviced. Oh, and they need to be able to do it remotely and safely, of course. And that latter bit is a particular sticking point, as oxidizers are "toxic, extremely corrosive and compressed" according to NASA, which is why the system is being developed for use both on land and in orbit -- why put a human in harm's way when a robot can do the job, right?
Image Credit: NASA