The European Space Agency says it has completed what it calls the largest digital camera ever built for a space mission - a one billion pixel array camera that will help create a three-dimensional picture of the Milky Way Galaxy.
Set to be launched onboard the ESA's galaxy-mapping Gaia mission in 2013, the digital camera was "mosaicked together from 106 separate electronic detectors." ESA says that Gaia's measurements will be so accurate that, if it were on Earth, it could measure the thumbnails of a person on the Moon.
According to the ESA, the camera was developed by e2v Technologies of Chelmsford, UK and uses rectangular detectors a little smaller than a credit card, each one measuring 4.7x6 cm but thinner than a human hair. The completed mosaic is arranged in seven rows of charge coupled devices (CCDs). The main array comprises 102 detectors dedicated to star detection. Four others check the image quality of each telescope and the stability of the 106.5º angle between the two telescopes that Gaia uses to obtain stereo views of stars.
The 0.5x1.0 m mosaic was assembled at the Toulouse facility of Gaia prime contractor Astrium France. Technicians spent much of May carefully fitting together each CCD package on the support structure, leaving only a 1 mm gap between them.
According to ESA, the Gaia satellite will operate at the Earth-Sun L2 Lagrange point, 1.5 million kilometers behind the earth, when looking from the sun. "As the spinning Gaia's two telescopes sweep across the sky, the images of stars in each field of view will move across the focal plane array, divided into four fields variously dedicated to star mapping, position and motion, color and intensity and spectrometry," the space agency stated.
Gaia is expected to map a billion stars within the Milky Way Galaxy over the course of its five-year mission, charting brightness and spectral characteristics along with their three-dimensional positions and motions.
From the ESA on Gaia's mission:
- Gaia's transmitter is weak, much less powerful than a standard 100 W light bulb. Even so, this equipment will be able to maintain the transmission of an extremely high data rate (about 5 Mbit/s) across 1.5 million km. ESA's most powerful ground stations, the 35 m-diameter radio dishes in Cebreros, Spain, and New Norcia, Australia, will intercept the faint signal transmitted by Gaia.
- The numbers foreseen in Gaia's celestial census are breathtaking. Every day it will discover, on average, 10 stars possessing planets, 10 stars exploding in other galaxies, 30 'failed stars' known as brown dwarfs, and numerous distant quasars, which are powered by giant black holes.
- Estimates suggest that Gaia will detect about 15, 000 planets beyond our Solar System. It will do this by watching for tiny movements in the star's position caused by the minute gravitational pull of the planet on the star.