The Space Race Disgrace – Brief Article
PETER BUNYARD EXPLAINS HOW HUMAN ACTIVITIES IN SPACE ARE DAMAGING THE EARTH’S FRAGILE ATMOSPHERE.
SPACE EXPLORATION, SATELLITE launches and the use of telecommunications could be having a devastating effect on the vital, protective properties of the outer atmosphere. Space is not as infinite — or as indestructible — as it seems, and we need to urgently rethink our activities there.
ACCORDING TO RUSSIAN academic MN Vlasov, of the Space and Ecology Centre in Moscow, not only are we leaving a mass of debris circulating at high speeds above the Earth, threatening satellites and manned spacecraft, but the exhaust gases from our space vehicles and rockets are dangerously transforming the properties of the rarified atmosphere several hundred kilometres above our heads. Add in energetic radiowaves used in telecommunication, and we have a recipe for disaster.
But should it really matter what goes on up there? As Vlasov makes clear, the outer atmosphere protects the Earth’s surface from a constant bombardment of high-energy electromagnetic radiation. We are now damaging those vital outer layers, with implications for human and environmental health.
Oxygen, the by-product of life-driven photosynthesis, is one of the most important agents for protecting life on Earth from ultraviolet rays. We are now well aware of the role of ozone ([O.sub.3]) in the stratosphere in protecting us from ultraviolet B, but perhaps less aware that the transformation of oxygen ([O.sub.2]) into ozone is the key to protection from ultraviolet C, the most energetic and destructive of the ultra-violets.
Simply, UV-C causes a molecule of oxygen to split into two atoms, one of which reacts with [O.sub.2] to form ozone. When struck by UV-B, the ozone splits back into its components and the cycle begins anew. Consequently, the creation and destruction of ozone absorbs ultraviolet and prevents it penetrating freely to the Earth’s surface.
Ever since a British Antarctic Survey team discovered the ozone hole in 1985, we have been rightly obsessed with CFCs and the ability of these relatively stable and unreactive chemicals to pass into the stratosphere, where their breakdown in bright sunshine releases ozone-destroying chlorine. But in focusing on CFCs as a prime cause of ozone depletion in the stratosphere, we have largely forgotten exhaust from space rockets. The launch of just one rocket may release the equivalent of 1 per cent of the total hydrogen found in the outer atmosphere. Every Space Shuttle flight discharges ten or more tonnes of hydrogen, which, at an altitude of 300 kilometres, forms a cloud that can spread horizontally over several thousand kilometres. Though not as massive as the Space Shuttle, the one hundred or so satellite launches a year are clearly having a major impact on the composition of the atmosphere, and hydrogen, like chlorine, is a destroyer of ozone.
The intense heat generated during the combustion of rocket fuel also produces nitrogen oxides, and nitric oxide (NO) in particular is another catalyst in ozone destruction. Some rocket systems, like the ‘Proton’, release large quantities of carbon dioxide, which lasts some 60 days before it is broken down through intense electromagnetic radiation from the sun.
The overall effect is to bring about changes in the density, pressure and circulation of the upper atmosphere, which in turn will affect the dynamics of satellite orbits and the propagation of radiowaves. But the disturbances go far beyond this. As rockets fire their way through the thin atmosphere of ‘near-Earth space’ they release vast amounts of heat, equivalent in their impact to an atomic bomb explosion in the lower atmosphere. Space shuttles, with their engines working while orbiting at altitudes lower than 200 kilometres, therefore pose a powerful threat to the controlled orbits of other satellites.
Debris from rocket launches and the destruction of orbiting satellites has led to thousands of tonnes of fragments, now constituting as much as 1 per cent of the total mass of the atmosphere above an altitude of 200 kilometres, travelling at high velocities, and in energy terms being equivalent to more than 3 per cent of the energy contained in the upper atmosphere. Certainly such debris threatens the safety of space shuttles and astronauts.
In essence, the ‘near-Earth space’ environment, with its fragile atmosphere, plays a vital role in protecting the Earth’s surface and therefore ourselves from damaging radiation, including powerful ultraviolet and other high-energy electromagnetic radiation from solar flares and other cosmic events. According to Vlasov, we urgently need international regulation of the use of the near-Earth system so that it continues to protect us and future generations. With space still considered a free-for-all, especially in view of the virulent competition to extend telecommunication to every individual through global television and satellite phones, we are indeed in danger of ‘blowing it’.
MN Vlasov and his colleagues EG Slekenichs and VV Grushin have published their concerns and findings in Cosmic Research, (Nos 29/32/34) as well as in Geomagnetism and Aeronomy.
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