Europe’s Gaia space observatory will cease science operations today as its cold gas propellant runs out after over a decade of observations. First launched in 2013, the astrometry telescope precisely cataloged nearly 2 billion objects within our Milky Way galaxy as part of an effort to create a novel three-dimensional galactic map.
The observatory orbits at Lagrange Point 2 (with its neighbor the James Webb telescope) roughly 1 million miles from Earth. Its two telescopes continuously scan the galaxy, while an array of 106 credit card-sized detectors—making the largest focal plane used in space—collects data on the luminosity and motion of stars, quasars, exoplanets, asteroids, and more. Gaia has scanned more than a billion objects over 70 times at a resolution 400,000 times fainter than what the naked eye can detect.
Data from Gaia’s observations—released in batches, with the fourth expected in 2026—have led to major discoveries, including starquakes and half a million new stars, as well as revealing the Milky Way merged with another galaxy early in its formation.