Gaia is scheduled to launch in late 2011 from Europe's spaceport in French Guiana. Following launch by a Soyuz-Fregat rocket, the Gaia satellite will spend a period of around one month in transit before arriving at the second Lagrange point of the Sun-Earth system. It is around this point, L2, which Gaia will be stationed in a large Lissajous orbit. Such positioning provides a very stable thermal environment and a moderate radiation environment, and allows the craft to avoid Earth eclipses for six years: five years of planned operational lifetime with the possibility of a further one year extension.
From its vantage point, Gaia will conduct its full-sky astrometric, photometric and spectroscopic survey. With a solar aspect angle of 45 degrees, Gaia will rotate once every six hours, with the spin axis itself precessing every 63 days. This revolving scanning law will allow Gaia's instruments to sweep the entire sky repeatedly, observing the billion celestial objects of its Galactic survey an average of 70 times each.
Data will be downlinked from the satellite to Gaia's ground stations at Cebreros, Spain and New Norcia, Australia, both of which employ 35-metre deep-space dish antennae. Mission operations will be carried out at the European Space Operations Centre at Darmstadt, Germany.
The graphic above shows the basic elements of Gaia's launch and operations in overview, as well as giving an impression of where L2 and Gaia's Lissajous orbit are positioned with respect to the Sun and Earth. It is available in jpg and tif format in medium and high resolution.
Graphic © ESA; Source: EADS Astrium