Gaia was launched Thursday aboard a Soyuz rocket from Europe's Spaceport in Kourou, the ESA reported from its Paris headquarters.
Gaia is designed to make accurate measurements of the positions and motions of 1 percent of the Milky Way's total population of roughly 100 billion stars, data that could answer questions about the origin and evolution of Earth's home galaxy, ESA scientists said.
Gaia is heading toward an orbit around a gravitationally stable point in space called L2 -- almost a million miles beyond Earth as seen from the sun -- where it will begin its five-year science mission.
"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," ESA Director General Jean-Jacques Dordain said. "It is down to the expertise of Europe's space industry and scientific community that this next-generation mission is now well and truly on its way to making groundbreaking discoveries about our Milky Way."
Five years of observing the motion of the galaxy's stars will create enough data so the stars can be put into 'rewind' to learn more about where they came from and how the Milky Way was assembled, and into "fast forward" to learn more about its eventual state, ESA scientists said.