Putting the 'tip' in tipping point: Could giant umbrellas, nets, harpoons and magnets capture the cloud of space junk scientists warn risks trapping us on Earth?

'We've lost control of the environment' warns author of new report



Up to 370,000 objects shrouding Earth, traveling at up to 22,000mph



Continual collisions pose 'potentially catastrophic risk' to astronauts




The amount of space junk orbiting earth has reached a 'tipping point' where continual collisions are thickening the already dense cloud shrouding the Earth, a Nasa report has revealed.



In practical terms, it means that the amount of junk floating around the planet will make it increasingly difficult for spacecraft to leave the planet, effectively trapping us on earth.



It also poses 'potentially catastrophic risk' to astronauts, satellites and the International Space Station.

Surrounded: This Nasa image shows the wider circle of space junk surrounding Earth, as well as the tighter cluster of objects in low orbit around the planet Junk cloud: Left, this computer-generated Nasa graphic shows objects of space junk in Earth's orbit that are currently being tracked - hundreds of thousands more are not being tracked - while, right, the size of the objects has been exaggerated in this CG image to add emphasis to the threat



WHAT IS SPACE JUNK?

Since the first object, Sputnik One, was launched into space 53 years ago, mankind has created a swarm of perhaps tens of millions of items of debris. The rubbish circling the planet comes from old rockets, abandoned satellites and missile shrapnel. It is estimated that there are 370,000 pieces of space junk floating in Earth's orbit. The picture above shows a ball of twisted metal, thought to be fallen space junk, on a farm in Queensland, Australia, in 2008.



'We've lost control of the environment,' said retired Nasa senior scientist Donald Kessler, who authored the report.

There are 22,000 objects in orbit that are big enough for officials on the ground to track and countless more smaller ones that could do damage to human-carrying spaceships and valuable satellites.

It is estimated that there are as may as 370,000 pieces of space junk floating in Earth's orbit, traveling at speeds of up to 22,000 mph.

Several solutions to retrieving or moving the space junk were put forward in an earlier report called 'Catcher's Mitt', by a Defense Department science think-tank.



It mentions giant cosmic versions of harpoons, nets, tethers, magnets and even a giant dish or umbrella-shaped device that would sweep up tiny pieces of debris.

While the new report does not recommend using the technology, Mr Kessler said it is needed.



He favours one private company's idea of a satellite that is armed with nets that could be sprung on wayward junk. Attached to the net is an electromagnetic tether that could either pull the junk down to a point where it would burn up harmlessly or boost it to safer orbit.

The latest evaluation report says: 'Scenarios uncovered conclude that the current orbital debris environment has already reached a 'tipping point'.



'That is, the amount of debris... Currently in orbit has reached a threshold where it will continually collide with itself, further increasing the population of orbital debris.



'The increase will lead to corresponding increases in spacecraft failures, which will only create more feedback into the system, increasing the debris population growth rate.'

The report, Limiting future collision risk to spacecraft, was commissioned by Nasa last April to evaluate its programmes on 'space junk', officially known as MMOD (Micrometeoroids and Orbital Debris).

While it says that the current U.S. programmes have used their resources well, it notes that there was a 10 year-plan between 1981 and 1991 to combat the problem, there has been no concerted effort since 1991.



Fallen: A piece of space junk that landed in a field in the rural U.S. in the 1990s

It also warns that the proposals to begin tackling the issues are expensive and could be sidelined or underfunded in the current economic climate, despite the threat it poses in the future.

Since the space age began 54 years ago, civilization has littered the area just above Earth's atmosphere with leftover boosters and other parts that come off during launches, as well as old satellites.

When scientists noticed that this could be a problem, they came up with agreements to limit new space junk and those plans had been working.

Those agreements are intended to make sure what is sent into orbit eventually falls back to Earth and burns up.

But two events in the past four years — a 2007 Chinese anti-satellite weapon test and a 2009 crash-in-orbit of two satellites — put so much new junk in space that everything changed, the report said.



The widely criticized Chinese test used a missile to smash an aging weather satellite into 150,000 pieces of 1cm debris and 3,118 pieces can be tracked by radar on the ground, the report said.

'Those two single events doubled the amount of fragments in Earth orbit and completely wiped out what we had done in the last 25 years,' said Kessler.