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An
expanding ring of man-made garbage circles the earth at hypervelocity, posing
an ever-growing threat to spacecraft and satellites. Space-faring nations
need to agree on a code of conduct to clean up humankind's final frontier. By Jerome Simpson
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While we toil with rising mountains
of waste here in Europe, spare a thought for that which already lies in
space. More than 9,000 objects larger than 4 centimetres have been catalogued
in orbit around the earth. Space debris was a leading suspect when the
Columbia space shuttle burnt up in February, killing all seven on board.
Though the theory was eventually ruled out, shuttle missions routinely
sustain minor damage from such refuse, making the threat of a catastrophic
incident very real. Human-made objects in space range in size from old satellites and spent rocket boosters (some of which have exploded in space into smaller parts), to flecks of paint and residues from solid rocket motor firings, and everything in between (including repair tools and an astronaut’s glove). Combined, this has resulted in "a total of 3,000 tonnes of space debris surrounding the earth today," said Alexey Yablokov, president of the Centre for Russian Environmental Policy. As of December 31, 1997, US Space Command had tracked and registered 25, 130 objects in space resulting from 3,896 launches. Smaller uncatalogued bits and particles that are larger than 1 cm are estimated to number more than 360,000. It may not sound like much of a threat, but those small particles typically travel at speeds of up to 10 kilometres per second -— or hypervelocity in space jargon — and routinely bed themselves quite deeply into shuttle windows, 80 of which have required replacement. Such miniscule objects can have disastrous consequences if they penetrate the spacesuit of an astronaut. Joel Williamson, a debris specialist at the University of Denver, said when speculating on the cause of the shuttle disaster that orbital debris or a meteoroid could have produced a small hole on entry and a fairly large, shotgun-like effect that would have rippled through other parts of the space plane, ringing it like a bell." In the most critical of scenarios, the cabin can lose pressure, suffocating the crew. Penetrate the skin Surprising then that the UN’s Committee on the Peaceful Uses of Outer Space noted in a 1999 technical report that "man-made space debris today poses little risk to the successful operations of the approximately 600 active spacecraft now in earth orbit." A common rule of thumb states, however, that objects greater than 1 millimetre will likely penetrate the skin of a satellite or a solar panel, those greater than 1 cm will cause the break up of satellites, and those greater than 10 cm can cause the total fragmentation of a satellite. So what are the dangers to earth-bound civilians? According to the same UN report, more than 16,000 space objects are known to have reentered the atmosphere over 40 years. No significant damage or injury has been reported, though this is in part due to the large expanse of ocean surface and sparse population density in many land regions. Yet about once each week, an object with a cross section of 1 square metre or more has reentered the earth’s atmosphere, and some fragments have survived the fall to earth. The risk of re-entry lies not only in mechanical impact, but also from chemical or radiological contamination to the environment. After the recent shuttle disaster, citizens were advised not to touch any of the pieces of the space plane for fear of chemical contamination from hazardous parts. Spacecraft engines can cause atmospheric and ground contamination, whether they’re part of a controlled or uncon trolled deorbit; in the past, they were built around nuclear reactors relying on Uranium 235 and today they run on radio-isotope-thermoelectric-generators. Such an incident occurred in January 1978 in Canada, when Cosmos 954, a nuclear-powered Soviet satellite, fell from orbit and left sizeable amounts of radioactive debris along a 2,000 km swath, sparking debate on the safe use of nuclear power in space. What does space junk mean for countries with emerging economies, like those in Central and Eastern Europe? Well, as the cost of satellite technology becomes more affordable and the region plans its own commercial satellites in popular orbits, the waste will proliferate and increase the attendant dangers. Spacecraft in low earth orbit or LEO (800 - 1,500 km above the earth)including telecommunications, navigational and remote-sensing satellites, are routinely bombarded by very small particles (less than 100 micrometres). The effects are normally slight but as the particle size increases, so too does the severity of the collision, with a case in point being the French CERISE spacecraft, struck and partially disabled in 1996 by an exploded Ariane upper rocket stage. "Unlike most terrestrial examples, orbital debris is not so easy to clean up," said Ray Williams, a research professor at George Washington University and the International Space University. "Stop polluting a stream, and in a few years it can recover. Stop putting debris into orbits and very little cleaning takes place, except in the lowest orbits, where atmospheric drag will eventually burn it up." Graveyard orbits
In March, a 15 km tether was released from a spent Delta II rocket stage in the hope it will generate enough thrust and electricity (via the earth’s magnetic field)to send it back into the atmosphere where it will burn up. Other options for cleanup include plucking debris from their orbit by spacecraft (pseudo garbage collectors), a technique which could prove advantageous in situations where the use of remote-sensing spacecraft, for instance, is giving one warring state an upper hand in conflict. NASA’s "Orion" project is looking into using high-powered, ground-based laser beams to actually deflect orbital debris out of the way of spacecraft and into the Earth’s atmosphere. An alternative is an in situ laser on board a craft such as the International Space Station. It all starts to sounds a bit too sci-fi for comfort. The first concerns regarding space debris were actually registered in 1957 by a group of astronomers. In 1999 the European Space Agency went as far as to note that "the uncontrolled growth of the space debris population has to be avoided in order to enable safe operations for the future." In 1967, the United Nations General Assembly adopted the Outer Space Treaty — a document that provides the basic, general principles for the use of outer space. "Outer space ...shall be free for exploration and use by all States," the document notes. So far, however, its signatories have tended to "appropriate" space rather than maintain it. Apart from obliging states to register space objects, no single piece of space legislation yet addresses space debris or how to avoid its generation. In recent years space-faring nations have adopted non-binding guidelines for reducing pollution from launch and satellite operations. "But in the long term, these are not expected to prove effective, especially when competition begins to undercut the natural desire to be good international citizens," said Ray Williams. Yet one must ask, is it ethical to foul space and leave our rubbish behind us for others to clean up?Spare a thought for Arthur C. Clarke, who in 1946, just one year after he proposed the concept of a constellation of geostationary earth orbiting communication satellites, lamented how humans have a way of embarking upon technological revolutions without systematically thinking about their effects on society. There are a handful of NGOs campaigning for the protection of space. Ryder Miller of the Astronomical Society of the Pacific noted that space ventures have one thing in common:"they have not incorporated the concerns or lessons of environmentalism or preservation into their plans to step outward into the solar system." He would like to see environmentalists lobby the UN and national space agencies "to agree to ethical guidelines" and "outer space environmental impact statements for the world to read." International space regime In March 2001, The Ecologist magazine called for "an expansion of international environmental laws" the laws that nations have agreed on to protect the oceans, for example, and the integration of space environmental statutes into "an international space law regime." The 2003 World Summit on Sustainable Development set the ground for developing a global environmental action plan, but overlooked the issue of truly global waste prevention and a management strategy for space junk. The shuttle disaster brought it home to us once more how risky space travel can be. The powerful atmosphere surrounding earth not only enables the right balance of gases and temperature to yield life here on earth but it also protects us from the dangers of space -- asteroids, deadly cosmic radiation and temperature extremes to name but a few. So while we pursue the goal of sustainable development on earth, it would be ironic to neglect the environment around our planet. Apart from increased risk for space missions, dumping in space can jeopardize unknown future opportunities like solar power stations beaming energy to earth, cosmic vacations and many more. We should use space to enhance our understanding of the earth and the processes that have contributed to its very existence, and to monitor and maintain this unique and fragile balance, and safeguard it for future generations. To this end, space technology can be used in countless ways. The potential is there. But do the world's policymakers see it the same way? — Jerome Simpson is the Head of REC's Information Programme and participates in the UNECE Remote Sensing Task Force which is currently exploring the use of Remote Sensing for Environmental Applications
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