Billion-pixel space camera Gaia passes critical tests
Sen—The most powerful camera ever designed for space is on track for launch next year following punishing tests to prove it can withstand that environment.
The European Space Agency's Gaia mission will scan the sky with a one-billion pixel detector, producing a 3D map of the Milky Way from its location 1.5 billion km from Earth.
Two telescopes aboard the spacecraft will chart the sky from an orbit around the Sun over five years, noting the position, motion, colour, brightess and composition of around a billion stars in our own galaxy and beyond. These observations will help astronomers learn how our galaxy formed and evolved.
Gaia is also designed to photograph large numbers of other celestial bodies, from asteroids in our own Solar System to more distant galaxies and around 500,000 quasars near the edge of the Universe.
The probe's camera is made up of 106 sensitive electronic detectors made by UK company e2v Technologies, of Chelmsford, Essex, who have also supplied imaging systems for the Curiosity probe now on Mars.
These are basically advanced versions of the chips found in home digital cameras. They were put together like a mosaic to make one huge sensor by scientists at Toulouse, France, for the European Space Agency.
Each detector is slightly smaller than a credit card but thinner than a human hair. Together they are powerful enough to record stars up to a million times fainter than the eye can see.
Gaia is due to be launched by a Soyuz-Fregat rocket from Baikonur in Kazakhstan. When it arrives at the spot called a Lagrangian point (L2) it will fly in a naturally synchronised orbit with Earth and operate at a super-chilled temperature of –110°C. A giant sunshade on the spacecraft will protect the instruments by keeping them permanently shielded from the heat of the Sun.
A cutaway of the Gaia spaceprobe showing its instruments. Credit: ESA
Scientists at Toulouse recently checked that Gaia’s service module, housing electronic units to run the science instruments, as well as the units that provide the spacecraft resources, such as thermal control, propulsion, communication, and attitude and orbit control, would function OK in extreme conditions.
During 19 days of tests, they enclosed it in a barrel-shaped chamber at Intespace's test facility where Gaia was subject to vacuum conditions and subjected to a range of temperatures. The process was similar to that which the James Webb Space Telescope will undergo inside a revamped chamber for NASA.
It experienced temperatures as low as –170°C and tests verified that the spacecraft's instruments could still work properly.
Gaia Project Manager Giuseppe Sarri said: “The thermal tests went very well; all measurements were close to predictions and the spacecraft proved to be robust with stable behaviour.”
He added: “The latest thermal test marks a major milestone achieved in the development of Gaia,” says Giuseppe. “It demonstrated that the service module is compatible with working in space and that we are on track for launch by the end of next year.”