Space junk calamity looms

Valuable spacecraft, such as the International Space Station, are at risk from space debris. Photo / NASA

Apotentially disastrous collision in space could render the edge of Earth's upper atmosphere unusable.

It's a matter of when, not if, such a calamitous event will take place, scientists say.

Space has become so crowded with defunct satellites, spent rocket parts and other manmade waste that a disastrous collision that damages valuable infrastructure is fast becoming inevitable.

Scientists from around the world descended on Canberra yesterday to brainstorm a solution.

Every time we watch TV, use GPS, or check the weather, we are relying on satellite technology. The problem is that as we keep sending them up there, the pile of orbiting junk gets bigger. Some predictions say space could become unusable in as little as 20 years.

As many as 170 million pieces of debris are thought to be circling Earth at speeds of over 27,000km/h. The most worrying part is we only know where 22,000 of them are.

The growing collection of untracked space debris is putting $900 billion worth of satellites and space infrastructure at risk, researchers warn.

Without the knowledge of where pieces of space junk are floating, valuable spacecraft such as the International Space Station, or vital defence and telecommunications satellites could be seriously damaged.

The CEO of Canberra's Space Environment Research Centre, Ben Greene, said lack of data on space junk was a major concern.

"There is so much debris that it is colliding with itself, and creating more debris. A catastrophic avalanche of collisions which could quickly destroy all orbiting satellites is now possible," he said.

His comments were almost identical to those he made in 2014 when the $150m centre was established to lead the way in addressing the space junk problem.

One US expert on space junk who travelled to Canberra called the threat of a truly damaging collision "inevitable".

Why is there so much junk?
It sounds crazy, but explosions are one concern. Unused fuel in abandoned satellites can cause them to blow up and turn one piece of space junk into thousands of smaller pieces.

Sometimes we even do it intentionally. In 2007, China tested an anti-satellite missile by shooting it at one of its old satellites, adding as much debris to the space junkyard as had accumulated in the previous 50 years, according to the Australian Academy of Science.

The collision between a defunct Cosmos satellite and an active Iridium satellite in 2009 created more than 1000 pieces of debris.

On top of that there is also general erosion caused by solar radiation and heat which, for example, causes paint strips to peel off satellites.

That doesn't sound like a big problem until you realise that one tiny paint flake in orbit can be enough to crack a window of the International Space Station.

Possible solutions
A robust tracking system remains a priority for researchers.

Astronomers also hope that laser technology, which is used to track space debris, can also prove useful.

Speaking to the ABC, ANU Professor Matthew Colless said the university's Research School of Astronomy and Astrophysics hoped to use lasers to remove smaller bits of space junk.

"If we increase the power of the lasers that we have to actually gently push small bits of space junk, that makes them fall back to Earth more rapidly and burn up harmlessly in the atmosphere," he said.

Other options have been explored in the past.

In February a plan by Japanese scientists to deploy a space junk "collector" - created with the help of a fishing net company - designed to be tethered to a space station resupply vehicle to slow the junk down and bring it into a lower orbit proved unsuccessful.