European camera eyes space junk

European camera eyes space junk

At the present time, no one has an accurate idea of how many objects with diameters of less than 10 cm are orbiting the Earth, what their orbits are, and how fast this debris is growing. Even space debris as small as a flake of paint moving at 8 km/s can cause catastrophic collision damage in a satellite.

To detect such space debris, the European Space Operations Center (Darmstadt, Germany) has commissioned a custom-built CCD camera from AstroCam (Cambridge, England) and Sira (Chiselhurst, Kent, England). The camera will be used in conjunction with a telescope, now being built on Tenerife in the Canary Islands by Carl Zeiss (Jena, Germany).

AstroCam engineers used four 2k x 2k CCD arrays from EEV (Chelmsford, England) butted together to form a single imager. Outputs from the CCDs are multiplexed and digitized into a Sun Workstation over a 6-Mbyte/s fiberoptic channel. According to Gordon Hopkinton, project manager with Sira, the front-illuminated EEV devices provide a more cost-effective method of imaging than back-illuminated devices. To reduce the thermal noise, the CCD devices in the camera head are cooled by liquid nitrogen to -90oC. "When operational, says Hopkinton, "the complete system will be capable of observing debris at altitudes from 300 to 36,000 km, the geostationary orbit where debris is becoming a serious problem."