Once it reaches its L2 parking orbit and begins observing, GAIA will log the position, brightness and color of every star that falls within its field of view. By repeating these observations throughout its mission, astronomers will be able to calculate the distance, speed and direction of motion of each star GAIA sees, chart variations in their brightness, and determine whether they have nearby companions.
This kind of detailed information about the Milky Way is unprecedented and may lead to important new discoveries about the evolution and structure of our galaxy. For updates about GAIA, stay tuned to the ESA. www.spaceweather.com