The Gaia mission, scheduled to launch Thursday morning (Dec. 19), could be a bonanza for discovering exoplanets, perhaps finding more than 2,500 new alien worlds, scientists suggest.
Designed and built by Astrium for the European Space Agency (ESA), the makers say the telescope is so sensitive that it could measure a person's thumbnail from the Moon, or to put it another way, detect the width of a human hair from 1,000km (620 miles) away
"It can do it with incredible
accuracy. It's the biggest camera ever put into space," said Ralph Cordey, head
of science and exploration at Astrium.
Gaia, a $1 billion (740 million euros) mission from the European Space Agency (ESA), aims to chart a 3D map of the Milky Way by surveying more than 1 billion stars, amounting to about 1 percent of the stars in the galaxy, using its billion-pixel camera. Its goal is to make the largest, most precise map of where Earth dwells by observing the position of each of these stars 70 times over five years.
To pinpoint the position of a star in 3D — a field known as astrometry — Gaia will measure the distance of the star from the sun. The satellite will do so by watching how its position shifts over time. As the Earth orbits the sun, the apparent positions of stars change with regard to each other due to how our viewpoint has moved, a phenomenon known as parallax.
Discovering a star's distance can narrow down many of its other details. For instance, the actual brightness of a star can only be determined by not only measuring how bright it appears but also how far away it lies and thus how distance might have dimmed its light. Once researchers know how bright a star actually is, they can determine how much fuel it must burn — that is, the star's mass. A star's brightness is also related to its width, and so discovering its brightness can help deduce its size. Knowing a star's mass and size then helps determine the strength of gravity on its surface.
Gaia will also scan the color of stars. This can help reveal details of their chemical makeup as well as its temperature, as the color of a star depends on its surface temperature. Knowing the brightness and color of a star can also help figure out its age and thus stage in its evolution. All in all, Gaia will help shed light on the composition, formation and evolution of the stars that make up the galaxy, researchers say.
Gaia will be most effective at detecting giant planets orbiting small stars. These planetary systems are prone to generating significant, noticeable wobbles in a star's position
Images: ESA/ATG medialab/ESO/S. Brunie