Gaia 'billion star surveyor' lifts off

A thought struck me the other day. The most important use of Gaia might be to give us enough warning that an asteroid or comet might
be on the way to do to us what one of them did to dinosaurs 65 million years ago.

Not the main use of Gaia, but might well be the most important feature by far

http://blogs.esa.int/gaia/2014/07/03/asteroids-at-the-photo-finish/

http://www.esa.int/Our_Activities/Space_Science/Gaia/Gaia_Go_for_science

29 July 2014
Following extensive in-orbit commissioning and several unexpected challenges, ESA’s billion-star surveyor, Gaia, is now ready to begin its science mission.

The satellite was launched on 19 December 2013, and is orbiting a virtual location in space 1.5 million kilometres from Earth.

Gaia’s goal is to create the most accurate map yet of the Milky Way. It will make extremely accurate measurements of the positions and motions of about 1% of the total population of roughly 100 billion stars in our home Galaxy to help answer questions about its origin and evolution.

Repeatedly scanning the sky, Gaia will observe each of its billion stars an average of 70 times each over five years. Small apparent motions in the positions of the stars will allow astronomers to determine their distances and movements through the Milky Way.