Europe launches satellite to map 1 billion stars

The European Space Agency successfully launched its star-surveying satellite Gaia into space today in a bid to produce the most accurate three-dimensional map of the Milky Way, and provide an insight into the evolution of our galaxy.
The satellite was lifted into space from French Guiana at 6:12 am (0912 GMT; 4:12 am EST) aboard a Russian-made Soyuz rocket, the agency said. It is heading to a stable orbit on the opposite side of the Earth from the sun, known as Lagrange 2, where it will arrive in about a month's time.
Timo Prusti, ESA's project scientist, likened the mission's goal to the switch from two-dimensional movies to 3D. At the moment, scientists are working with a largely "flat" map of the galaxy. "We want to have depth," he said.

Once Gaia arrives at the Lagrange 2 point some 1.5 million kilometres (930 million miles) from Earth, the satellite will unfold a 10-meter (33-feet) circular sun shield. This will protect Gaia's sensitive instruments from the rays of the sun, while simultaneously collecting solar energy to power the spacecraft.
Using its twin telescopes, Gaia will study the position, distance, movement, chemical composition and brightness of a billion stars in the galaxy, or roughly 1 per cent of the Milky Way's 100 billion stars.
The data will help scientists determine the Milky Way's origin and evolution, according to Jos de Bruijne, deputy project scientist for the Gaia program.

"The prime importance of this mission is to do galactic archaeology," he said in a phone interview from French Guiana. "It will reveal the real history of our galaxy."

The project is the successor to ESA's Hipparcos satellite, which was launched in 1989 and measured the position of 100,000 stars in the Milky Way.
Gaia, which is named after an ancient Greek deity, will go far beyond that. Scientists have compared its measuring accuracy to measuring the diameter of a human hair from 1,000 kilometres (600 miles) away.
"There is still a lot that we don't understand about the Milky Way," said Andrew Fox, an astronomer with the Space Telescope Science Institute in Baltimore, Maryland. He is not involved in the project, but his position at the science centre is funded by the European Space Agency.

ESA has dubbed Gaia the "ultimate discovery machine" because its sophisticated instruments will allow scientists to look for small wobbles in stars' movements that indicate the presence of nearby planets.
"Those are the stars that people are going to go out and look for planets around, and ultimately for signs of life," said Fox.