The European Space Agency’s Milky Way-mapping space mission Gaia, which involves UCL researchers, has completed its sky-scanning phase, racking up more than three trillion observations of two billion stars and other objects over a decade to revolutionise our view of the galaxy. Launched on 19 December 2013, Gaia’s fuel tank is now approaching empty – it uses about a dozen grams of cold gas per day to keep it spinning with pinpoint precision. But this is far from the end of the mission.