The European Space Agency’s Gaia telescope has a five-year mission: to catalog and monitor a billion stars in the Milky Way galaxy.
The unprecedented survey will reveal properties of each star, including temperature, luminosity and physical composition. The resulting 3D map will show the true structure of our region of the Milky Way, which is difficult to determine from the Earth’s position within the galaxy.
Gaia operates at the Lagrange-2 point in the Earth-sun gravitational system. Far beyond the moon’s orbit, L2 is one of several stable points where the gravity of the sun and Earth balance each other out. An advantage of an L2 orbit is that Earth does not obscure a large area of the sky, as is the case for the low-Earth-orbiting Hubble telescope.
Gaia will measure each of its target stars about 70 times over the course of its five-year mission, monitoring distances, movements and changes in brightness. This averages 40 million observations per day. Gaia’s 1 billion target stars amount to only one percent of the total stars in the Milky Way galaxy. Gaia carries twin telescopes and the highest-resolution image sensor ever sent into space, with more than 1 billion pixels (1,000 megapixels, in camera terms).
Gaia’s high-gain antenna transmits data back to Earth. A total of more than one million gigabytes is expected to be transmitted by mission’s end.