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Space Junk Threatens Cascade of Collisions

The sheer amount of debris in low-Earth orbit is tipping space dangerously close to a cascade of hazardous collisions, scientists announced at a four-day international meeting on the subject this week. And there is an “urgent need” to fly satellites without creating new fragments and to remove those that are already there.

Here’s what we know about space junk:

After some 5,000 successful satellite launches, scientists estimate there are roughly 30,000 items circling the Earth that are larger in size than 10 centimeters, BBC News reported — a virtual garbage belt surrounding the Earth. Of these, 17,000 baseball-sized chunks are being regularly monitored from the ground, and 10,000 of these are fragments resulting from explosions and collisions in orbit, according to this European Space Agency video:


Most of the objects are in low-Earth orbit. Most collisions occur near the Earth’s poles. And many are caused by accidental explosions due to unused fuel onboard.

Certain actions taken can reduce the problem, according to the European Space Agency: depleting unused fuel, venting pressure tanks, switching off batteries and removing satellites from heavily frequented orbits at the end of their missions. This is known as “passivation.”

But that doesn’t solve the problem posed by objects already in space.

On February 10, 2009, for example, the Iridium 33 satellite collided with the defunct Kosmos 2251satellite at a speed of 26,000 miles per hour, creating 2,000 additional pieces of space debris. And as more objects accumulate, more of these collisions are likely to occur.

Scientists are also exploring spacecraft that would capture and “deorbit” some of the larger and most threatening pieces of space junk.

In October 2007, Hari Sreenivasan interviewed Donald Kessler, former head of NASA’s orbital debris research program, who said that a piece of space debris has the potential of “totally catastrophically” breaking up a spacecraft. Plus, he explains, one collision can create a spray of additional debris:

“They end up producing an awful lot of small fragments,” he said. “And the larger of those large fragments then go on to hit something else and cause it to break up and you get essentially a chain reaction of events, where you get an increasing frequency of things breaking up as a result of collisions.”


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“In 1980, a humpback whale in the Gulf of Maine started doing something different. All its neighbours would catch small fish by swimming in circles below them, blowing curtains of bubbles, and then lunging straight up at the corralled shoal. Then one individual, out of the blue, started smacking the water surface with its tail before diving down and blowing its bubbles.”

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Rebecca Jacobson, Patti Parson and David Pelcyger contributed to this story.

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