The European Space Agency has awarded EADS Astrium a contract worth €317 million to develop and build the Gaia satellite. The goal of Gaia’s space mission, currently planned for launch in 2011, is to make the largest, most precise map of the Galaxy to date.
EADS said Gaia would be the most accurate optical astronomy satellite ever built so far. It will continuously scan the sky for at least five years from a point in space known as the second Lagrangian point (or L2), located at about 1.6 million kilometres from Earth, in the opposite direction to the Sun. This position in space offers a very stable thermal environment, very high observing efficiency (since the Sun, Earth and Moon are behind the instrument field of view) and a low radiation environment.
Gaia’s goal is to perform the largest census to date of our Galaxy and build a highly accurate 3D map. The satellite will determine the position, colour and true motion of 1,000 million stars. Gaia will also identify as many as 10,000 planets around other stars, and discover several tens of thousands of new comets and asteroids in our own Solar System.
EADS said that the accuracy of Gaia measurements would be so high that if Gaia were on the Moon, it could measure the thumbnail of a person on Earth. The spacecraft will use the global astronomy concept successfully demonstrated on its predecessor, ESA’s mission Hipparcos, also built by EADS Astrium, which successfully mapped over 100,000 stars in the late 1980s.
Gaia will be equipped with a scientific payload, including the most sensitive telescope ever made. Its design is based on silicon carbide (SiC) technology, also used on Herschel, ESA’s next infrared mission. The focal plane is about half a square metre and features 1,000 million pixels.
Gaia will also be equipped with two key components. The first one is a deployable sun-shield, covering an area of one hundred square metres, to minimise the temperature fluctuations on the highly sensitive optics. The second is a micro-propulsion system which will be used to smoothly control the spacecraft so as not to disturb the optics during the sky scanning.