More than $300 billion worth of satellites are drifting through space in geosynchronous orbit (GEO)about 22,000 miles from Earths surfacebut many of these have been retired due to normal end of useful life, obsolescence or failure. Some 20,000 objects larger than a mobile phone that are currently tracked and an estimated half-a-million objects no bigger than a British pound coin that cant be surveyed may turn lethal as they hurtle through space at a speed of more than 8 kilometres (5 miles) a second, says London-based Royal Aeronautical Society. Not only can space debris affect critical equipment such as communications satellites, but it can also
endanger manned space flights.
Most of those are useless fragments of once-useful objects, which were created by explosions, collisions or missile tests. For instance, an accidental collision between the Iridium-33 and Kosmos-2251 satellites in 2009 caused them to shatter into 2,200 (recorded) fragments. Smaller space debris is much harder to track, but National Aeronautics and Space Administration (NASA) estimates that up to 500,000 objects larger than 1 cm, and 135 million particles over 1 mm in size may now be orbiting the Earth.
But how can mission controllers on the ground remove those troublesome pieces of space junkincluding defunct satellites, spent rocket stages and other pieces of man made debrisfrom their dangerous orbits Technology readily available today could mitigate the space junk threat. By taking only five satellites out of orbit each year for the next 100 years, while adhering to an international understanding called the 25-year rule, space agencies could stabilise the orbital environment, according to a NASA study.
Space debris is becoming a serious issue, and many space agencies have started working on solutions. Retired satellites are typically put into a GEO-disposal or graveyard orbit, but the growing number of man-made objects and debris in this low-orbit graveyard is leading to an increased risk of collisions, which in turn threatens to trigger a cascade effect, according to ESA.
NASA and ESA studies show that the debris environment can be kept stable, but it requires the removal of around five large objects per year, the agency said. Japans Space Agency JAXA has plans to send a rocket and satellite into orbit, where the latter will unreel a wire net approximately 300 meters long. The net will then generate a magnetic field, and if all goes well, catch some of the debris.
An Australian team is working on a project to zap orbital debris with lasers from Earth to reduce the growing amount of space junk that threatens to knock out satellites with a cascade of collisions. The project is very realistic and likely to be working in the next 10 years.
Scientists believe there are more than 300,000 pieces of
debris in space, made up of everything from tiny screws and bolts to large parts of rockets, mostly moving in low orbits around Earth at tremendous speed. Australia now has a contract with NASA, the US space agency, to track and map space junk with a telescope equipped with an
infra-red laser at Mount Stromlo Observatory.
But $20 million from the Australian government and $40 million in private investment will help the team set up as the Cooperative Research Centre (CRC) to develop better lasers to track tiny pieces of debris, importing techniques from astronomy used to remove the blurring of the
The ultimate aim is to increase the power of the lasers to illuminate and zap pieces of junk so they burn up harmlessly as they fall through the upper atmosphere. There are already 17,000 trackable objects larger than a coffee cup, which threaten working missions with catastrophic collision. Even a 1 cm nut could hit with the force of a hand grenade.
To tackle the problem, the European space agency is designing a hunter-killer space probe to track down and destroy defunct satellites and so halt the growth of the burgeoning cloud.
The e.DeOrbit probe would deploy a Roman gladiator-style array of nets and harpoons to first trap rogue satellites and then drag them downwards until they burn up in the atmosphere.
The European satellite and rocket maker Astrium together with the regions space agencies, is likely to develop mono- and multi-chaser platforms to grab hazardous objects bigger than cars in space with robotic arms or harpoons and nets, and send them up into less crowded orbits or down to burn in the
There are signs that some governments are beginning to take the menace of space-debris (and its clearing) seriously. German satellite maker OHB AG said last November that it signed an accord with the countrys space administration to study possible uses for a spacecraft developed by the USs Sierra Nevada Corp, including removals of decommissioned satellites.
In about 20 years, space debris might be destroyed using lasers, although the biggest challenge will be creating a global body to govern such operations since military operations in space are currently banned by an international treaty.