Debris Belt Threatens Future Space Travel

Published on Tuesday, 16 August 2011 08:27

 By Benedict Gifford

Frontiers are a messy business. 

On the American frontier a man couldn’t make his merry way to the saloon without stepping over one, maybe as many as three corpses.  And so it is with space.  In fifty years of space exploration we have put a lot of stuff up there and, contra the proverb, what goes up doesn’t always come down.  I think the idiom took root before we broke the atmosphere.

A mere 200 KM above our heads, low-Earth orbit (LEO) is the orbit-of-choice for the International Space Station and most satellites.  The busiest thoroughfare in space is also the biggest junkyard in space, with an estimated 5500 tonnes of debris freewheeling around the globe.  Most of the weight is made up by obsolete satellites and spent rocket casings though Ed White’s glove, a pair of pliers, a tooth brush and several cameras aren’t helping.  Clearing the debris is a matter of some urgency because it is thought that when there is enough of it collisions between debris will cascade until the LEO is all but unnavigable in something called Kessler Syndrome.

Several clean up operations have already been suggested including the UK’s Cubesail a NASA laser and a kind of electronic lasso but the latest offering comes from the Italian Space Agency (ASI).  The ASI propose launching a two-armed robotic cleaner-satellite into LEO to hunt out the larger pieces of debris.  Once found, the robot apprehends the errant debris with one arm whist the attaching a propellant kit with the other. Primed debris can then be launched back into the atmosphere and a fiery and convenient death. A single robot flying from junk to junk could dispose of 5-10 such items per year.

The robot is an elegant way of cleaning up some of the larger pieces of debris but whether or not this in itself would be enough to preempt Kessler Syndrome is moot.  Donald J. Kessler, the Nasa scientist who predicted the cascade, has been crying Cassandra-like at the international space community since 1978 and it is worth taking a second to look at the syndrome:  A window is one piece of glass.  You stick a post-it with ‘I love you’ on it to a brick, hoof it though the window and you have lots of pieces of glass and an impressed girlfriend.  And so when space debris collides with other debris it produces more debris each of which has an increased chance of hitting another piece of debris because the skies are consequentially more populated.  If the proliferation of debris occurs faster than removal of debris (by forces natural or otherwise), a chain reaction can occur that would render LEO an all-but-impassable debris belt: Kessler Syndrome.

The Kessler Syndrome. Imagine this, but with a lot more white.

The effect is already being felt by space faring nations – the lifespan of satellites has been dramatically shortened and shuttles are being flown rather embarrassingly tail-first around space in an attempt to avoid the kind of damage a single paint fleck can do to a window.  Indeed a fatal collision with a piece of debris is now considered the No.1 threat to manned space missions.

The solution. Picture may not be factually accurate.

Some organisations are concerned that the debris has already reached critical mass and normally-so-sensitive-about-these-things-China's 2007 shooting down one of it's own satellites created a staggering 25% more debris and a good deal of ill-will in the international community.  Indeed it seems that whilst the ASI's robot might be able to pluck a few of the larger pieces from the sky (and stop them from spalling) it seems that we'll have to overcome the frontier sense of provinciality before we stand a chance of averting the kind of disaster that would render our near-space an advert to the universe of our collective hubris.

And this is was supposed to a light-hearted story about a real life Wall-E.

© Images are courtesy of NASA.