The European Space Agency (ESA) has launched an advanced telescope designed to detect a billion stars and provide the most detailed map yet of the Milky Way.
The Gaia telescope was successfully hoisted by a Soyuz-STB-Fregat rocket from ESA's space base in Kourou, French Guiana, the agency reported in a webcast on Thursday.
"All is functioning normally," an ESA commentator said.
The satellite was to be deployed 42 minutes after launch.
The 740 million-euro ($A1.15 billion) device, the most sophisticated space telescope ever built by Europe, aims at building an "astronomical census" of a billion stars, or around one per cent of all the stars in the Milky Way.
By repeating the observations as many as 70 times throughout its mission, Gaia can help astronomers calculate the distance, speed, direction and motion of these stars and build a 3D map of our section of the galaxy.
It will also help in the search for planets beyond our solar system - as many as 50,000 so-called extrasolar planets could be spotted during the satellite's five-year life, astronomers hope.
Gaia will also observe the asteroid belt between Mars and Jupiter to help the search for any rocks that may one day threaten Earth, and keep a watch for exploding stars, called supernovae, which are rarely observed in real time.
