ESA’s Gaia mission to study a billion suns launched

Washington – ESA on Thursday launched its Gaia mission, whose aim is to study a billion suns.

Gaia is destined to create the most accurate map yet of the Milky Way. By making accurate measurements of the positions and motions of 1 per cent of the total population of roughly 100 billion stars, it will answer questions about the origin and evolution of our home Galaxy.

The Soyuz launcher, operated by Arianespace, lifted off at 09:12 GMT. About ten minutes later, after separation of the first three stages, the Fregat upper stage ignited, delivering Gaia into a temporary parking orbit at an altitude of 175 km.

A second firing of the Fregat 11 minutes later took Gaia into its transfer orbit, followed by separation from the upper stage 42 minutes after liftoff.

Ground telemetry and attitude control were established by controllers at ESA’s operations centre in Darmstadt, Germany, and the spacecraft began activating its systems.

The sunshield, which keeps Gaia at its working temperature and carries solar cells to power the satellite, was deployed in a 10-minute automatic sequence, completed around 88 minutes after launch.
Gaia is now en route towards an orbit around a gravitationally-stable virtual point in space called L2, some 1.5 million kilometres beyond Earth as seen from the Sun.

Next day, engineers are going to command Gaia to perform the first of two critical thruster firings to ensure it is on the right trajectory towards its L2 home orbit. About 20 days after launch, the second critical burn will take place, inserting it into its operational orbit around L2.

A four-month commissioning phase will start on the way to L2, during which all of the systems and instruments will be turned on, checked and calibrated. Then Gaia will be ready to begin its five-year science mission.

Gaia’s sunshield will block heat and light from the Sun and Earth, providing the stable environment needed by its sophisticated instruments to make an extraordinarily sensitive and precise census of the Milky Way’s stars.