NEWS

Beware, the sky may well fall on our heads

When pieces of the destroyed Russian space station MIR began to enter the earth’s atmosphere in March 2001, the scientific community held its breath. The question was: Would they fall into the sea between Chile and Oceania or were their calculations way off? As the pieces of the spaceship, the last symbol of the Soviet space era, rained into the Pacific Ocean one after the other, scientists heaved a collective sigh of relief. The prediction that the pieces would fall within an imaginary geographical parallelogram of 200 by 6,000 kilometers, had come true. The pieces of MIR that bombarded the Earth caused no damage. After all, thousands of calculations, by the finest instruments and best and brightest minds in the world, had gone into tracking their orbits. «If only,» experts say, «we were able to do the same with the thousands of other pieces that are circling the earth where the atmosphere meets space.» Astrophysicists, astronomers, NASA researchers and thousands of other scientists openly voice concern about space debris. Thousands of pieces of junked satellites that were launched for scientific and military reasons, rocket parts, empty fuel tanks and other garbage that has simply lost its way aimlessly roam space near the Earth – about 400 to dozens of thousands of kilometers above the planet’s surface. In the future, they could seriously damage the globe’s space health. Greek and British scientists sat around the same table at an event organized by the British Council in Thessaloniki in order to discuss the «possible dangers of heavenly bodies in the Earth’s neighborhood.» The debate both brought out the extent of the problem and also delivered the judgment that it was time the issue left the narrow bounds of the scientific community and be put to public opinion. Dangers from the sky tend to be considered in terms of meteorites crashing into the Earth. A scenario beloved of Hollywood, it has taken up reams of celluloid. But the relatively greater danger is for the sky to fall on our heads, as the Gauls in the Asterix cartoons feared – and it’s a subject on which there is virtual silence. «There is a lack of information about space debris,» said Nikolaos Spyrou, professor of astronomy at Thessaloniki’s Aristotle University. «Most people do not know of the problem, which undermines the future of space travel itself and the future place of residence of human beings, if one accepts the notion that a number of space stations will be built in the Earth’s near space in the future.» Over 10,000 objects The numbers given by the British and Greek experts could not pass unnoticed. «From the Sputnik launch in October 1957 until today, over 3,500 space missions have been carried out. As a consequence of this activity, special sensors have tracked down some 10,000 objects in the Earth’s near space, a figure that is augmented by 200 additional objects per year, chiefly due to the collisions between them.» Of these objects, around 5 percent (some 500 objects) continue to perform a useful function. In addition, a small percentage (less than 1 percent) of registered satellites have radioactive materials, which is expected to cause special problems in the future. But «the real number of objects of human origin orbiting round the Earth, up to 1 centimeter in size, is multiple the official figure,» experts say. How space garbage came into being is not difficult to explain. Space launches and projects are the most important factors in the increase, along with the unscheduled dismemberment of satellites. Solar activity is often deadly in its impact, as in the case of Skylab (a fragment of which killed a cow in Australia). Professor Spyrou noted another, less well-known effect of space garbage, especially on the science of astronomy. The existence of thousands of such objects around the Earth, glittering in the sun’s rays, create a halo that renders telescopes useless. Many observatories, due to light pollution from cities and space garbage are having difficulty studying the starry sky. Year by year, their vision is diminishing. «Within one or two decades, this material – if it’s not removed – will pose a serious threat to spaceships, space stations and human beings on Earth,» Spyrou said. The effects of human activity on near space will be joining the known environmental problems of our age, such as the greenhouse effect, the hole in the ozone layer, nuclear weapons, species extinction and biological warfare. The problem is so important that experts stress that an international treaty is needed for the use of near space in order to introduce ecological management of the Earth’s space environment. One treaty is not a magical solution. The issue is multifaceted. Apart from the clearly scientific and technical issues, there are the economic, legal and international issues in the use and protection of near space for political and military purposes. As the British Council conference concluded, «what is needed are international cooperation and treaties, as well as enforcement of those agreements, as is the case with the protection of Antarctica, the law of the sea, atmospheric pollution and the protection of the ozone layer.»