Space Junk Or Orbital Debris Explained

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New Delhi: Japan on Friday lauched Kounotori (‘White Stork’), a space capsule that will carry supplies to the International Space Station , and experiment with an ingenious method to clean up space debris orbiting around earth.

Orbital debris or ‘space junk’ consists of non-natural objects of varying size and form that orbit the earth. These include space vehicles that are no longer active, objects used by spacecraft during their missions, and debris produced when they were destroyed.

More than 20,000 of these bits of ‘junk’ are bigger than a softball (an alternative form of baseball), and pose a threat to active spacecraft – like the International Space Station – since they can move as fast as 28,163.5 kmph, says the US’ National Aeronatics and Space Administration (NASA). But they don’t even need to be that big to be hazardous, since at such great speeds, even bits of paint can cause damage, the space agency explains.

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However, actual instances of spacecraft being destroyed by space junk have been few and far between: a French satellite sustained damage after a collision with debris in 1996, and American satellite was taken out by a non-function Russian satellite in 2009, NASA adds.

So how precisely will Kounotori’s experiment contribute to the effort to remove this debris?

The capsule is experimenting with a 700-metre metallic line – called an ‘electrodynamic tether.’ Electricity generated by the tether as it moves in the earth’s electromagnetic field is expected to slow down space junk, pull them of their orbits and into the earth’s atmosphere, after which the they’ll burn away before it can reach the earth’s surface.

As the US’s National Public Radio put it, it’s akin to “essentially unspooling a clothesline in space.”

But that’s not the only way experts are trying to purge space of man-made junk. Among the projects that have been proposed, or that scientists working on: earth-based lasers that can destroy debris, and tentacled ‘janitor’satellites that can ‘sweep up’ junk.