Mapping our galaxy with a billion-pixel camera

New Delhi: The European Space Agency is sending the $1.2 billion Gaia mission to space to catalog a billion stars, planets, asteroids and supernovas for generations of astronomers.At the heart of the mission is a billion-pixel camera which will give scientists more clues about the origin and evolution of the universe, and in particular our own galaxy. At approximately one billion pixels, it's the largest digital camera ever built for a space mission.While the telescope will be focusing mainly on our own Milky Way galaxy, the camera will also be mapping other celestial bodies, including galaxies and quasars near the edge of the observable universe.The makers of the camera, Astrium for the European Space Agency (ESA), say the telescope is so sensitive that it could measure a person's thumbnail from the Moon, or detect the width of a human hair from 1,000km (620 miles) away.The mission's primary aim is to build a three-dimensional map of our galaxy. It will help in measuring precise distances to a billion stars. Scientists estimate that there are at least 100 billion stars in our galaxy. In addition, Gaia is expected to discover up to ten thousand planets beyond our Solar System, as well as hundreds of thousands of asteroids and comets within it.Gaia's twin telescopes will see an average of 40 million stars every day over its five-year mission, with a launch atop a Europeanized version of the Russian Soyuz rocket from the Guiana Space Center on the northern coast of South America.Made by the UK's e2v Technologies, the “one-billion pixel” array is made up of 106 charge coupled devices (CCDs). Each of the rectangular CCD is a little smaller than a credit card in area, although thinner than a human hair in thickness. These CCDs have precisely joined together into a 0.5 x 1-meter (1.6 x 3.3-foot) seven-row flat mosaic. While 102 of the sensors are assigned to star detection, the other four will check the image quality and angle of the Gaia spacecraft's twin telescopes, used to obtain 3D stereoscopic images of the stars.The array's support structure is built from ceramic-like silicon carbide, which is lightweight. The material resists deformation caused by temperature changes. Ralph Cordey, head of science and exploration at Astrium, said the spacecraft cost 400 million euros ($549 million) to build, with the total cost of the mission exceeding 740 million euros ($1.02 billion). If successful, Gaia will add to the knowledge gained from NASA's Hubble Space Telescope, which is still in operation, and ESA's Hipparcos satellite, which gathered data until 1993.The value of putting a billion-pixel camera into space has been championed by Robert Massey from the UK's Royal Astronomical Society.One of the main objectives of this amazingly ambitious mission is to help in the hunt for exoplanets -- new worlds beyond our own solar system.NASA's Kepler mission has so far confirmed the existence of 167 exoplanets with hundreds more being investigated, but Cordey anticipates Gaia will likely discover thousands of new planets, while further missions will be able to uncover more detail about them.