What is Gaia?

Gaia is ESA’s mission to create the most accurate three-dimensional map of almost two billion stars throughout our galaxy and beyond, mapping their position, motion, brightness, temperature, and composition. This huge stellar census will provide the data needed to tackle an enormous range of important questions related to the origin, structure, and evolutionary history of our galaxy.

The mission’s additional objectives reveal Gaia as the ultimate discovery machine. It is expected to find thousands of planets beyond our Solar System and to observe hundreds of thousands of asteroids and comets within it. Gaia also observes millions of quasars and other galaxies outside the Milky Way.

Gaia was launched on 19 December 2013 and is placed in an orbit around the Sun, at the second Lagrange point (L2), which is located 1.5 million km from the Earth in the anti-Sun direction. Gaia operates in a Lissajous-type orbit around L2.

At its heart, Gaia contains two optical telescopes that work with three science instruments to precisely determine the location of stars and their velocities, and to split their light into a spectrum for analysis.

During its mission, the spacecraft spins slowly, sweeping the two telescopes across the entire celestial sphere. As the detectors repeatedly measure the position of each celestial object, they detect the object’s motion and any changes in it through space.

Gaia is a fully European mission. The spacecraft is controlled from the European Space Operations Centre (ESOC, Darmstadt, Germany) using the three ground stations Cebreros (Spain), Malargüe (Argentina), and New Norcia (Australia). Science operations are conducted from the European Space Astronomy Centre (ESAC, Villafranca, Spain). Additional scientific staff is located at the European Space and Technology Centre (ESTEC, Noordwijk, Netherlands).

The Gaia Data Processing and Analysis Consortium (DPAC) processes the data to be published in one of the largest stellar catalogues ever made.