With over 11 years out in space, at the L2 Lagrange Point, ESA’s mission Gaia built one of the most detailed maps of our galaxy with observations of nearly two billion objects.
The Global Astrometric Interferometer for Astrophysics (Gaia) history starts off with ESA’s Hipparcos mission, the first astrometry spacecraft that catalogued more than 100.000 stars with high precision at the beginning of the 90s. Building on the legacy of Hipparcos’ success, Gaia was born with the primary objective of having a highly detailed 3D space catalogue of the stars in our galaxy. In detail, the mission’s objectives were to measure the position and velocity of approximately one billion stars; determine their brightness, temperature, composition and motion through space of about one billion stars – roughly 1% of the Milky Way’s stellar population. In addition, Gaia aimed to discover new asteroids, comets, brown dwarfs, supernovae and quasars.
Launched on December 19th, 2013, from Kourou in French Guiana. Gaia started collecting an outstanding amount of data for scientists to analyse and help understand our universe. This was possible by one of astronomy’s oldest techniques to measure the position and motion of objects in space, astrometry. Measuring large distances in space is possible with stellar Parallax, the apparent movement of a foreground object (the Earth around the Sun) and objects in the background. And the spacecraft did just that with its two telescopes, an astronomer, a photometer and a spectrometer.
Having successfully ended its scientific mission on January 15th, 2025, ESA’s Space Operation Centre officially turned off the spacecraft’s subsystems on March 27th, sending it into a retirement orbit. Gaia provided an immense volume of data to scientists who discovered celestial objects that have never been seen with high accuracy, revolutionising our understanding of the galaxy’s structure, formation and evolution. Its legacy will continue to influence astrophysics for decades to come.