e2v, a leading designer, developer and manufacturer of high performance imaging sensors has delivered over 150 Charge Coupled Devices (CCD) imaging sensors for Gaia, a European Space Agency (ESA) cornerstone mission.

Due to launch in 2012, Gaia's goal is to map the positions, parallaxes and proper motions (movement across the sky) of around 1 billion objects in our galaxy, the Milky Way, to an unprecedented accuracy. For the brightest objects, radial velocities (movement towards and away from the satellite) will be measured and photometric data taken to determine the composition of the objects.

The result of this will be the most detailed map of the Milky Way ever produced which will improve our understanding of our galaxy immensely.

At the heart of these astrometric, spectroscopic and photometric instruments is the largest focal plane array ever to be flown in space. This focal plane array will contain a mosaic of 106 large area, high performance e2v CCD91-72 imaging sensors, which are custom designed, manufactured and tested by e2v. The CCDs will be operated synchronously in TDI mode, effectively working as a near giga-pixel array.

There are three variants of the CCD91-72, each optimised for different wavelengths in the range 250 to 1,000nm. e2v's specialist technology has been implemented into each CCD, with functionalities like charge injection, antiblooming and TDI gate structures to meet the specific needs of the mission.

The CCD package is 3 sided buttable, to minimise the dead space between CCDs when they are tiled together in the mosaic. All CCDs have also been through e2v's world leading, back thinning process.

Having completed the design and extensive evaluation of these CCDs, e2v is now close to completing manufacture and test. Over 150 devices have now been delivered during the flight phase of the project, comprising of flight models, flight spares and engineering models.

These are currently being integrated by the satellite prime contractor, EADS Astrium, to form what will be the very impressive focal plane array ahead of the proposed 2012 launch. Quite simply, without these CCDs the Gaia mission would not be possible.

Giuseppe Sarri, project manager of GAIA at ESA said "Gaia continues a European tradition for pioneering astrometry, building on the expertise generated by the first space-based astrometry mission, Hipparcos. Gaia will outdo its predecessor in terms of accuracy, limit magnitude and number of objects. It will pinpoint the position of stars with accuracy in the order of 10-300 microarcseconds (10 microarcseconds is the size of ten-cent coin on the Moon, when viewed from Earth). All this is thanks to companies like e2v, who are able to push technology to the extreme."

e2v Marketing and Applications Manager, Jon Kemp said, "e2v is immensely proud to have successfully delivered more than 150 large area, high quality image sensors to EADS Astrium for the Gaia mission which will truly impact human kind's understanding of our universe."