Wednesday, February 8, 2012

CultureLab - Space junk makes an impact at the IMAX

Lisa Grossman, physical sciences and space reporter
(Image: Space Junk3D, LLC)

Earlier this year, the International Space Station had to fire its thrusters to dodge a potentially dangerous collision with a piece of debris from a dead satellite. The shrapnel was one of around 3,000 pieces blasted into the space station’s orbit when China deliberately blew its Fengyun 1C satellite to smithereens 5 years ago.
That was just the latest narrowly averted disaster due to space junk - the cloud of abandoned rocket stages and other space age flotsam that enshrouds the Earth. The new IMAX film Space Junk 3D makes the sobering case that humans have polluted not just the planet, but up to thousands of kilometres above its surface as well.
The film follows Don Kessler, retired head of NASA's Orbital Debris Program Office and "father of space junk", who was one of the first to warn of the dangers of space junk. Until the 1970s, most scientists ascribed to the "big sky" theory - basically that space is so huge, there's no way we'll ever fill it up.
But certain orbits proved to be more useful for communications and GPS satellites than others, and these paths tend to be shared by the majority of satellites. The useful sections of sky, at least, may not be so big after all.
What’s more, as Kessler pointed out back in the 70s, when two pieces of space debris collide they produce hundreds of smaller pieces of debris. These can cross paths with other pieces of junk and create more fragments, and so on. Because there's typically nothing to pull orbiting space junk down out of the sky, the cloud of debris will only grow.
This doomsday scenario, now called "Kessler syndrome", was brought home in 2009, when a dead Russian satellite collided with a US communications satellite. Around 100,000 pieces from this collision alone are now thought to be scattered throughout low-Earth orbit, within a couple of thousand kilometres of Earth’s surface. In total, there are about 6,000 tonnes of space junk zipping around low-Earth orbit at speeds upwards of 28,000 kilometres per hour - so fast that even a paint chip could do serious damage to the space station.
With 3D visualisations of the swarming clouds of junk, animations of collisions between everything from satellites to galaxies, and footage from Meteor Crater in Arizona, the film gives viewers plenty to lose sleep over.
But it's not all doom and gloom. The final minutes reveal real plans astronomers and space engineers have to clear the litter. Tethers that create drag by interacting with the Earth's magnetic field could be used to pull debris into the Earth's atmosphere to burn up. Or perhaps solar sails, which work by propelling satellites using the pressure of sunlight, could help de-orbit satellites once their working lives are done. One suggestion involves flinging a giant fishing net into space to sweep junk away.

"We can bring back the pristine environment we would like space to be," Kessler said. Here's hoping.
Space Junk 3D will be showing at a number of international science centres and museums on various dates throughout 2012.

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