In the first crash of its kind, two communication satellites collided on February 10, 2009 in orbit shooting out a pair of huge debris clouds and poising a slight risk to the International Space Station (ISS). The collision occurred nearly 800km over Siberia and involved a US Iridium commercial satellite (launched in 1997) and a defunct Russian satellite Cosmos2252 (launched in 1993).
Iridium satellite weighed 560 kg, while the Russian craft nearly a tonne. The incident raised questions over how it was allowed to happen and what will become of the cloud of orbital debris, which adds to one of the biggest headaches in space. The collision has fuelled concerns over lack of traffic controls in space and the rising volumes of junk that endanger vital satellites and manned flights.
Just a month after the Iridium accident, a stray motor chunk hurtled toward the International Space Station. Cruising at an altitude of 220 miles, astronauts aboard the $100 billion laboratory were going about their daily chores at around noon EDT when they received a warning- Prepare for possible impact. The crew was directed to scramble into the station’s equivalent of a lifeboat, an attached Russian-made Soyuz capsule. It would give them a chance to abandon ship, if necessary. After a few minutes, the motor zipped by, missing the ISS by just a few miles in space terms, a close call.
Then on December 1, 2010, with almost no warning, a small chunk from a different Cosmos satellite hurtled toward the ISS, coming within a mile of a direct hit. Due to its speeding-bullet velocity, even this fragment could have had an impact equal to a truck bomb and would have blown everything to smithereens.
Incidents like these serve as clear signs that something must finally be done about space junk. Its proliferation threatens not only current and future space missions but also global communications mobile phone networks, satellite television, radio broadcasts, weather tracking, and military surveillance, even the dashboard GPS devices that keep us from getting lost.
The number of manufactured objects cluttering the sky is now expected to double every few years as large objects weaken and split apart and new collisions create more Kesslerian debris, leading to yet more collisions.
If we look at a brief history of space junk, the Telstar-1 satellite which relayed the first phone calls and TV signals across the Atlantic is still in the space after failing in 1963. By 1985, the number of catalogued orbiting debris objects of over 10cm in diameter had reached nearly 6,500. By 2005, these increased to 10,000. In 2007, a Chinese test weapon shot down the Fengyun-1C satellite, creating some 3,000 new pieces of trackable space junk. At present, the number of catalogued debris objects has crossed the 15,000 mark.
Space debris comprises the ever increasing amount of inactive space hardware in orbit around the earth as well as fragments of spacecraft that have broken up exploded or otherwise become abandoned. About 50 per cent of all trackable objects are due to in-orbit explosion events (about 200) or collision events (less than 10). Litter in orbit has increased in recent years, in part because of the deliberate break-ups of old satellites. It has become so bad that orbital debris is now the biggest threat to space shuttle in flight, surpassing the dangers of lift-off and return to Earth.
Though active satellites and the ISS have thrusters to manoeuvre out of harm’s way, it will be at the cost of using up precious fuel. Between the launch of Sputnik on 4 October 1957 and 1 January 2008, approximately 4600 launches have placed some 6000 satellites in to orbit, of which about 400 are travelling beyond geostationary orbit or on interplanetary trajectories. It is estimated that only 800 of these satellites are operational today, roughly 45 percent of these are both in Low Earth Orbit (LEO) and Geo Stationary Orbit (GEO).
So far, nations have been operating under a Big Sky theory, that space is so vast that the odds of a collision were ‘infinitesimal’. China added significantly to space debris when it used a ground based ballistic missile to blow apart an obsolete weather satellite in a January 2007 arms test. The United States used a missile from a Navy warship to explode a tank of toxic fuel on crippled US spy satellite in February 2007.
Currently, the US Space Surveillance Network is using ground- based radar, optical and infrared sensors to track more than 7500 objects. The minimum size of trackable object is about 10cm for a LEO, and about lm for the GEO. Only about 6 per cent of these catalogued objects are active satellites. Over 40 per cent are fragments of disintegrated satellites and upper stages of rockets. However, the vast majority of manmade debris comprises objects smaller than 10cm which are not tracked during routine operations. It is estimated that 30,000 to 100,000 objects larger than 1cm range are in space.
Space debris is an inherently international problem whose solution requires international cooperation. The Inter-Agency Space Debris Coordination Committee (IADC) is an international governmental forum for the worldwide coordination of activities related to the issues of man- made and natural debris in space. The IADC facilitates exchange of information on space debris research activities between member space agencies. It also facilitates opportunities for cooperation in space debris research, to review the progress of ongoing cooperative activities, and to identify debris mitigation options.
The IADC member agencies include the Agenzia Spaziale Italiana (ASI), British National Space Centre (BNSC), Centre National d’Etudes Spatiales (CNES), China National Space Administration (CNSA), German Aerospace Center (DLR), European Space Agency (ESA), Indian Space Research Organisation (ISRO), Japan Aerospace Exploration Agency (J AX A), National Aeronautics and Space Administration (NASA), National Space Agency of Ukraine (NSAU), and the Russian Federal Space Agency (ROSCOSMOS). The IADC has a Steering Group and four specified Working Groups covering measurements (WG1), environment and database (WG2), protection (WG3) and mitigation (WG4).
In spite of such cooperation, the US defense department has warned that junk of abandoned rockets, shattered satellites and missile shrapnel in space may cause collision between satellites, destroying communication facilities on earth. The space junk, dubbed ‘an orbiting rubbish dump’,
also comprises nuts, bolts, gloves and other debris from space missions and no satellite can be ‘reliably shielded’ against them.
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’.
The ‘chain reaction’ can leave some orbits so cluttered with debris that they become unusable for commercial or military satellites. Moreover, large pieces of debris threaten the lives of astronauts in space shuttles or at the International Space Station.
In view of the alarming situation, the United Nations Office for Outer Space Affairs (UNOOSA) has issued Space Debris Mitigation Guidelines, urging the removal of spacecraft and launch vehicles from the earth’s orbit after the end of their missions. According to UNOOSA, space needs “policies and laws to protect the public interest”