As
a burning streak appeared in the Australian night sky on Thursday, speculation arose
about its origin: a burning plane, a meteor, a UFO?
The
object, travelling across Hobart in Tasmania toward northern New South Wales and
southern Queensland (from south to northeast Australia), was a chunk of the Soyuz,
the Russian rocket, says scientists. Russia used the rocket on July 8 to launch
the Meteor-M weather satellite. It was a three-tonne, seven-metre long
cylindrical object that is among more than 300,000 pieces of space junk
orbiting the Earth, maintains Dr. Ben Greene, chief executive of the Cooperative
Research Centre at Mount Stromlo Observatory near Canberra (Canberra Times, July
11, 2014).
And
what is the likelihood that someone could be hit be a piece of space junk? One person
will be hit by a piece of space junk and killed in the next 50 years. Greene
says “that’s what we expect, but there’s a higher chance of winning the lottery
without buying a ticket.” That’s because the space junk usually collide with
each other and disintegrate before ever reaching the surface of a planet. In
fact, most of the 6,500 tonnes of space junk will eventually re-enter the Earth’s
atmosphere, “but not for decades or centuries,” says Dr. Jonathon McDowell,
astronomer at the Harvard-Smithsonian Center for Astrophysics in America.
Ninety
tonnes of space junk re-entered Earth’s atmosphere in 50 separate incidents
(re-entries) in 2013, maintained McDowell.
But
NASA, the American National Aeronautics Space Administration, were monitoring
the skies, and alerted astronomers in Australia of the pending re-entry of the
junk into the Earth’s atmosphere, said professor Brian Schmidt at the Research
School of Astronomy and Astrophysics in the Australian National University in
Canberra, the capital of Australia. “This one was decaying rapidly and the
prediction of the path was confirmed because everyone saw it.”
Space
debris has landed – in locations such as Australia and Mongolia – but due to
the remoteness of the landing site, no one has been injured. Most debris lands
in the sea.
Nevertheless,
for astronomers, it was a rare event.
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