AT ORBITAL SPEEDS a tennis-ball-sized piece of space junk can obliterate a satellite. It makes good sense, then, to track orbiting debris, the better to steer spacecraft away from danger. That this is hard was underscored on April 23rd, as a SpaceX capsule sped toward the International Space Station . The crew were preparing to sleep when ground control hastily announced they had just 20 minutes to complete a safety procedure before a potential impact.
Radars operated by America’s Department of Defence have long been the biggest providers of “space situational awareness”. Little more than a decade ago, position fixes were generally accurate only to within a few hundred metres. Since then, says François Laporte, an expert at CNES, France’s space agency, the accuracy of America’s debris tracking has improved by an “extraordinary, marvellous” order of magnitude, to a few tens of metres.
One problem is that there is no consensus on the best way to predict an object’s future orbit. To do this its position must be recorded several times, to observe how its path is being altered by the gravitational pulls of the Earth, Moon and sun, the pressure imposed on it by solar radiation and, in low orbits, the drag caused by wayward wisps of air from the upper atmosphere. Different teams often come up with different results, says Dr Konacki, who was once a delegate to the EU SST Consortium.
Besides using radar, debris can also be tracked optically. In collaboration with Curtin University, in Perth, Lockheed Martin runs FireOPAL, a system of 20 cheap cameras aimed at the sky from various parts of Australia. For several hours at dawn and dusk, when these cameras are in the dark but sunlight still illuminates debris orbiting above, the cameras take pictures every ten seconds.
Like careers of the future.
I love what the Woz is doing in this space. ;)
Typical capitalism. Instead of solving the root cause of a problem we charge to monitor it.
thanks
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