Washington/London: Junk of abandoned rockets, shattered satellites and missile shrapnel in space may cause collision between satellites, destroying communication facilities on earth, the US defence department has warned.
According to scientists, the debris scattered in the earth`s orbit is reaching a "tipping point" and pose a threat to the $250 billion space services industry.
A single collision between two satellites or large pieces of "space junk" can send thousands of pieces of debris spinning into orbit, triggering an "uncontrolled chain reaction".
Services such as global positioning systems, telephone networks, television signals and weather forecasts are at risk of crashing to a halt.
The "chain reaction" can leave some orbits so cluttered with debris that they become unusable for commercial or military satellites. Large pieces of debris threaten the lives of astronauts in space shuttles or at the International Space Station, the Pentagon said in its review.
The report, which was sent to Congress in March and not publicly released, said space is "increasingly congested and contested" and warned the situation is set to worsen, The Telegraph reported.
According to Bharath Gopalaswamy, an Indian rocket scientist researching space debris at the Stockholm International Peace Research Institute, there are now more than 370,000 pieces of junk compared with 1,100 satellites in low-Earth orbit (LEO), between 490 and 620 miles above the planet.
The space junk, dubbed "an orbiting rubbish dump", also comprises nuts, bolts, gloves and other debris from space missions.
"This is almost the tipping point," Dr Gopalaswamy said. "No satellite can be reliably shielded against this kind of destructive force."
In February last year, a crash between a defunct Russian Cosmos satellite and an Iridium Communications Inc. satellite left about 1,500 pieces of junk whizzing around the earth at 4.8 miles a second.
A Chinese missile test destroyed a satellite in January 2007, leaving 150,000 pieces of debris in the atmosphere, Dr Gopalaswamy said.
The Chinese missile test and the Russian satellite crash were key factors in pushing the United States to help the United Nations issue guidelines urging companies and countries not to clutter orbits with junk, the Pentagon`s Space Posture Review said.
The United Nations Office for Outer Space Affairs (UNOOSA) issued Space Debris Mitigation Guidelines last year, urging the removal of spacecraft and launch vehicles from the earth`s orbit after the end of their missions.
Space needs "policies and laws to protect the public interest", saud Mazlan Othman, director of UNOOSA.
"We should have all the instruments to make sure that lifestyles are not disrupted because of misconduct in space when people switch the television to watch the World Cup next month in Johannesburg," he added.