Gaia, a European mission to map the Milky Way, has successfully launched from the European Space Agency’s base in French Guiana.

Its two telescopes were dispatched from the launch pad in Kourou at 9.12 GMT on a Soyuz-Fregat rocket. The spacecraft will now journey 1.5 million kilometers to its destination — Lagrange point L2, a gravitationally stable point beyond Earth’s orbit around the Sun.

Mission controllers confirmed that Gaia completed the most crucial part of its launch and early orbit, including deploying its 10.5-metre-wide sunshield, designed to provide the craft with solar power and shade its sensitive equipment from sunlight.

The mission is designed to chart 1 billion stars, with the aim of helping astronomers to answer fundamental questions about the origins of our Galaxy as well as uncover tens of thousands of previously unseen objects, such as asteroids and black holes (see ‘Europe’s star power’).

Its two telescopes will rotate once every six hours, sweeping over the same regions of space and building up a precise map of star locations using a 1-billion-pixel camera. As it moves around in orbit, Gaia will also make use of the parallax effect to measure the distance between Earth and 10 million stars to more than 99% accuracy, building up a three-dimensional map.

Gaia is scheduled to arrive in position in three weeks and start routine operations in April 2014. The spacecraft will remain in position for five years, collecting data to be published in its star catalog in 2021.

The mission is the first major attempt to precisely measure the positions of the stars since the European Space Agency’s High Precision Parallax Collecting Satellite (Hipparcos), which launched in 1989 and ran until 1993. Hipparcos measured the distances to about 118,000 stars, but only 400 to the degree of precision planned for Gaia.

This article is reproduced with permission from the magazine Nature. The article was first published on December 19, 2013.