People And Their Problems

New Delhi, 15 February 2008

Space Activities

GRIM & GROWING MENACE 

By Radhakrishna Rao

Like the proverbial Damocles Sword, a partially crippled and wobbling American defence spacecraft is likely to hit the earth month-end or early March. Where exactly would it hit and descend, no one knows. The satellite, essentially designed for spying and surveillance, can no longer be kept under control. “Numerous satellites over the years have come out of orbit and fallen harmlessly. We are looking at potential options to mitigate any possible damage this one may cause,” is all the US National Security Council is willing to say.

Evidently, like all other satellites this spacecraft too carries hydrazine, a colorless and toxic chemical, similar to ammonia which is used for keeping the satellite in its pre-determined orbit. Period firing of onboard hydrazine thrusters prevents the possibility of the satellite straying from the orbit. However, with much of this chemical fuel not being used by the satellite and the fuel tank surviving the searing heat while re-entering the atmosphere, it could prove hazardous in case of human contact.

An uncontrolled descent could risk exposure of US secretes, says American defence and intelligence analyst John Spike on the issue, adding that such spy satellites are disposed of through a controlled entry into the ocean so that no one can access the secrets!   

Remember, the largest uncontrolled re-entry by the American-built Skylab had spread global panic after it started wobbling in space in 1979. The 78-tonne advanced space station launched by the National Aeronautics and Space Administration (NASA) ultimately made soft-landing on the watery mass of the Indian Ocean region around Australia, much to world relief.

However, much less publicized plunge was the crash of nuclear-powered errant Russian Ocean Watch satellite Cosmos-954 in January 78. It warned a complacent world of the looming threat of nuclear radiation from the heavens. Fortunately, this satellite meant to keep a tab on the naval strength of the adversaries burnt over a remote, uninhabited part of North Canada, scattering radioactive debris from its nuclear power pack over a wide area. The Soviets were forced to pay large sums for only the clean-up operations.

Other incidents were: In 1961, Cuban President Fidel Castro had complained of a chunk re-entering from a dead American satellite and killing a Cuban cow; a medium-sized metallic piece of an American spacecraft landed on a street junction of a small town in Wisconsin, US; in 1983 the American usable space transportation system Space Shuttle narrowly escaped being hit by a piece from the Soviet Inter Cosmos Vehicle. In July 96, a French defence satellite CERISE was slightly hit from European space vehicle Ariane.  

However, the first-ever case of death or injury due to the impact of descending rocket stages was reported from China in early 95. While India was busy celebrating its Republic Day, the Chinese Long March-1 Vehicle carrying Apstr-2 Communications satellite crashed halfway up in space. The hurtling rocket stages during descent killed a couple, besides injuring several others.

Both the Indian Space Research Organisation (ISRO) and European Space Agency (ESA) have expressed concern over the possibility of uncontrolled spacecraft hitting earth and causing damage. Space scientists have stressed the need to evolve strategies aimed at preventing the spacecraft from accidentally re-entering the atmosphere and hitting earth.

In addition, there is a growing concern over tranquil and peaceful outer space getting polluted, thanks to the rapidly growing dump yard of components and parts from dead satellites and launch vehicles. This pollution belt holds a serious threat to operational spacecraft and manned missions. It is perhaps a grim tribute to man’s unqualified success in giving a “cosmic dimension” to the terrestrial problem of pollution!

Another major challenge before the global Space community, is to develop techniques for detecting objects smaller than 10-cm, which roam freely in space, posing grave threat of crippling multi-billion dollar satellite missions. Researchers suggest that weak laser beams could be used to remove minor space debris from the orbit of active satellites.

Significantly, many pieces of dead satellites continue to stay in orbit indefinitely if they attain what is called the first cosmic speed. Only objects that slip below an altitude of 120-150 kms re-enter the atmosphere and blaze down as unidentifiable pieces on earth. The collision hazard posed by Space debris is mainly because of the high energy impact caused by its rapid acceleration.

Clearly, Space debris can hit and damage 1,000-plus spacecraft circling the earth in various orbits. The effect of a collision between space debris and satellites carrying nuclear power source is particularly worrying. This was the reason why the launch of the American Saturn probe, Cassini, carrying plutonium as a power source, was stiffly opposed by American environmental groups.

Besides, posing a direct threat to human life and property, space activities are also being blamed for the growing atmospheric pollution. Toxic exhaust from the American space shuttle has been found to be responsible for atmospheric disruption of varying degrees. In order to obviate the problem of pollution associated with satellite launches, researchers have called for an increase in the use of liquid fuel stages in a launch vehicle.

Overcrowding is yet another problem plaguing outer space. The geostationary orbit often described as a “real estate of the final frontier” is experiencing near-total congestion. Located 36,000-kms above equator, the orbit is an ideal “space slot” for positioning communications satellites. From here, a communications’ spacecraft can provide round the clock coverage. For how long, let’s ask the Space scientists. ---INFA

 (Copyright, India News and Feature Alliance)