By Syed Akbar
Hyderabad: For astronauts and space scientists, it's the problem of
space "garbage" that keeps them bothering up in the skies.
Called space debris or junk, the space garbage has piled up to such an extent
that two of the world's topmost space research agencies, Nasa and Esa have
now taken up a mission to keep the environs of outer space clean and tidy.
The European Space Agency has already achieved "significant progress" in
preparing measurements and modelling the space-debris environment.
Space scientists express concern over the increase in debris pollution in the space
environment which surrounds the earth.
Space debris or garbage is nothing but objects left in the space by man
during explorations. Astrophysicists estimate that there are about one lakh small
and big particles suspended in the space and posing threat to future space
explorations, as space tourism is all set to get a boost in the next five
to 10 years.
Dr Qi Lin of Beihang University, Beijing, China, Dr Igor Molotov of
Moscow, Russia, Dr Hugh G Lewis of Southampton, UK, and Dr Canan Li of
Harbin, China, besides Christophe Bonnal of France, Nicholas L Johnson of
United States have reviewed the problem of space debris.
The US Space Surveillance Network has identified as many as 7500 objects
through ground-based radar, optical and infrared sensors. The Network could
identify only objects which are not smaller than 10 cm in low Earth orbit and
one metre in the case of geostationary orbit. Objects which are smaller or
bigger than these are out of the surveillance of the USS Network.
Only six per cent of these objects listed by the Surveillance Network are
active satellites and more than 40 per cent of them are fragments of
disintegrated satellites and upper stages of rockets. This shows how much
"pollution" man has caused in the outer space during the last 50 years of
space exploration and travel.
"The basic hazard in space caused by debris is damage or even destruction by
collision. Current risk levels are small, but are steadily increasing. For
some space missions space debris has already become a safety issue and active
protection through shielding will be needed. The International Space Station
is an example," say the space scientists.
Though NASA and ESA are removing space debris through methods like air-
drag perturbations, the problem continues to grow as the rate at which the
garbage is piling up is more than the rate of removal. "This will sooner or
later lead to a major increase in the amount of debris as a consequence of
collisions between Earth-orbiting objects," they warn.
The is currently pursuing four main activities regarding the environment like
development of a meteoroid and debris reference model, radar measurements
of mid-size debris, optical measurements and analysis of spacecraft surfaces
returned from space.
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