Monday, March 21, 2005
Space Junk
A sobering image released by the European Space Agency shows how much "space debris," i.e. old satellites and other man-made garbage litters the Earth's orbit.
There are 8,700 objects in orbit that are larger than four inches and therefore "observable," but only 7% are operational spacecraft, ESA says. A full half are decommissioned satellites, spent upper rocket stages, and mission related objects like lens covers. The remaining 43% is detritus from 160 spacecraft orbital explosions recorded since 1961.
These explosions have also generated as many as 150,000 pieces of smaller junk one half to ten inches long. It's this debris that worries rocket engineers. "These are too small and numerous to be individually tracked but could cripple or kill any craft they hit," ESA says. Since they can't be seen, scientists have to rely on sophisticated probability models and software to navigate through the orbiting landfill.
"If you calculate the combined profile area of all satellites in orbit, you find that the average time between destructive collisions is about 10 years," said Heiner Klinkrad, ESA debris specialist. "It's now standard practice that near-Earth satellites carry an allowance of fuel simply for taking evasive manoeuvres during the craft's operational lifetime."
There are 8,700 objects in orbit that are larger than four inches and therefore "observable," but only 7% are operational spacecraft, ESA says. A full half are decommissioned satellites, spent upper rocket stages, and mission related objects like lens covers. The remaining 43% is detritus from 160 spacecraft orbital explosions recorded since 1961.
These explosions have also generated as many as 150,000 pieces of smaller junk one half to ten inches long. It's this debris that worries rocket engineers. "These are too small and numerous to be individually tracked but could cripple or kill any craft they hit," ESA says. Since they can't be seen, scientists have to rely on sophisticated probability models and software to navigate through the orbiting landfill.
"If you calculate the combined profile area of all satellites in orbit, you find that the average time between destructive collisions is about 10 years," said Heiner Klinkrad, ESA debris specialist. "It's now standard practice that near-Earth satellites carry an allowance of fuel simply for taking evasive manoeuvres during the craft's operational lifetime."
