The European Space Agency's Gaia orbital observatory was launched here Thursday with a mission to map the Milky Way.

Equipped with a billion-pixel camera, the satellite rode into space atop a Russian Soyuz rocket that blasted off before dawn from Europe's Spaceport in Kourou.

Gaia will not reach its permanent orbit for several weeks and must undergo four months of commissioning before embarking on its five-year mission.

The ESA expects Gaia to observe 1 billion stars - about 1 percent of the Milky Way's stellar population - on 70 separate occasions over the satellite's working life, providing the basis for a three-dimensional map of our galaxy.

"Gaia promises to build on the legacy of ESA's first star-mapping mission, Hipparcos, launched in 1989, to reveal the history of the galaxy in which we live," agency chief Jean-Jacques Dordain said in a statement.

The probe's data archive is projected to top 1 million gigabytes - the equivalent of some 250,000 DVDs - by the conclusion of the mission in 2019. EFE