International space travel threatened by orbital junk

Posted by Aharon Etengoff

Chicago (IL) -A dangerous collection of orbiting space debris is expected to pose an increasing threat to international space travel. 

"The threat posed by orbital debris to the reliable operation of space systems will continue to grow unless the sources of space debris are brought under control," NASA's chief orbital debris scientist Nicholas Johnson told the House Space and Aeronautics Subcommittee.

According to Space.com, the Department of Defense's Space Surveillance Network is currently tracking over 19,000 objects in Earth orbit larger than four inches (10 cm). However, there are an estimated 300,000 orbiting objects that exceed a half-inch (1 cm) in size.

"It is clear to me that if the spacefaring nations of the world don't take steps to minimize the growth of space junk, we will eventually face a situation where low Earth orbit becomes a risky place to carry out civil and commercial space activities," said Congresswoman Gabrielle Giffords (D-Arizona), the committee's chair.

Indeed, recent simulations conducted by NASA suggest that the odds of potential space collisions have increased exponentially, as even objects the size of a grain of sand can impact with the power of a bowling ball moving at 100 mph.

The first incident between two large satellites has already occurred. In February 2009, a defunct Russian military orbiter collided with a live American commercial satellite. Wayward space junk also forced the crew of the International Space Station to take refuge in an escape ship as discarded materials passed their fragile facility.

Professor Lawrence Wein of Standford University noted that removing orbiting objects within 25 years of their original launch date could help significantly reduce the chances of collisions in space.

"Spacecraft are supposed to have enough 'gas' in their tanks to propel them downward toward the atmosphere when their life cycle is concluded. But international compliance, while perhaps greater than 50 per cent, is not extremely high," said Wein. "Our analysis predicts that, despite a slow increase in the rate of collisions over the next millennium, the risk of a catastrophic collision to an operational spacecraft can be kept below one chance out of 1,000 for all future time if we focus on very high compliance of deorbiting spacecraft from low Earth orbit after their useful life."

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