ESA's Gaia spacecraft to create 3D map of the Milky Way

The European Space Agency's Gaia spacecraft will launch next week to create a 3D map of stars across the Milky Way.

Gaia, scheduled for launch Thursday, will spend five years orbiting the sun at a distance of 1.5 million kilometers from Earth.

The data collected will include the precise distances of stars from the Earth, accurate to around one percent.

"It's going to be the most accurate and the most detailed 3D map of stars there has ever been," said Dr Ralph Cordey, head of science at Astrium UK, a company involved in the building of the spacecraft.

The ESA's Hipparcos mapping mission, which ran from 1989 to 1993, catalogued the position, proper motion and distance of more than 100,000 stars up to 300 light-years away from the sun.

Gaia, by comparison, will probe 1 billion stars up to 30,000 light-years away. The spacecraft will take measurements for about one percent of the Milky Way's 100 billion stars, using some 70 measurements for each.

"[Gaia] will see the motion of the star but as a big planet moves around a star, the star itself should move a little bit because of the gravity of the planet," said Albert Zijlstra at the University of Manchester. "It is a minute effect but Gaia should see it -- but only for nearby stars and only for large planets."

Researchers also hope to get a better understanding of dark matter, which cannot be seen but does exert a large gravitational force on celestial bodies. The motion of stars will help astronomers estimate the distribution of dark matter. They will use two telescopes to look at stars from two directions simultaneously, and take images with a billion-pixel camera.

"What this video processing unit does is it captures the important interesting parts [of the data], the tracks of the stars for example as they go across the camera, and it sends those back to earth," said Cordey.

[The Guardian] [ESA Gaia]