The ESA’s Space Situational Awareness Preparatory Programme stems from the threat of collisions between objects in orbit, harmful space weather and potential strikes by natural objects that cross the Earth’s orbit.
UK involvement is through the Science and Technology Facilities Council’s Chilbolton Observatory, which tracks objects in low-Earth orbits and Space Insight’s Starbrook sensor, which is trained higher up.
‘With more than 20,000 tracked objects, including around 1,000 operational satellites orbiting the Earth, we need to be aware of potential collisions. At closing speeds reaching 50,000km per hour, even the smallest bits of space debris can cause serious harm to spacecraft,’ said Prof Richard Crowther, a space debris expert from the UK Space Agency.
Starbrook is a ground-based wide-field optical sensor capable of surveying the increasingly large number of objects in the higher-Earth orbits, such as the geostationary and GPS-type orbits. It detects objects as small as 1m in size at up to 40,000km from the Earth.
Meanwhile, the Chilbolton Advanced Meteorological Radar comprises a high-powered transmitter and sensitive receiver installed on the 25m-diameter fully steerable dish antenna to track and characterise satellites in low-Earth orbit.
Currently, objects with a radar cross-section of 1m2 are detectable at ranges of 1,000km. In the future, it is planned to modify the radar to characterise targets in more detail by exploiting their polarimetric and Doppler signatures.
Dr Jon Eastment at the Chilbolton Observatory said: ‘We have obtained very encouraging initial results during the recent ESA-sponsored campaign, having successfully tracked a variety of satellites at ranges out to more than 2,000km.’
The ESA is in the process of designing its own space surveillance sensors, with a procurement phase expected after the next ESA Ministerial Council meeting scheduled in 2012. Until its own sensors are ready, ESA will continue to collect data from existing sensors of participating member states in order to test data-processing and sensor-tasking facilities.