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WORD COUNT
618
MAY 27, 2009
SPACE
TRASH IS NO JOKE – by Victoria Samson
The Hubble
Space Telescope, once the joke of late-night comedians, has proved to be
an invaluable resource in photographing the universe. NASA has
undertaken a very expensive mission to send up the Space Shuttle
Atlantis in an attempt to extend the telescope’s lifespan so that it can
continue to serve its purpose. So imagine how much of a loss it would be
if a piece of space debris rammed into it, ending its mission
prematurely. It and all the other spacecraft must keep a wary eye out
for the hundreds of thousands of pieces of manmade debris that circle
our planet.
On May 13,
a four-inch piece of space trash passed within 1.7 miles of the Hubble.
At its current altitude of 350 miles, this means the two objects were
moving at such dizzying speeds that an impact could be catastrophic.
This
orbital debris was not, like many other pieces, a cast-off part from an
earlier space mission. Instead, it was created in January 2007 when
China tested an anti-satellite (ASAT) weapon, using one of their
ballistic missiles to shoot down an aging Chinese weather satellite.
This event, according to Joseph Rouge, head of U.S. National Security
Space Office, created debris that “will be
around 3,000-4,000 years.”
China certainly was not the first country to test ASAT weapons – the
United States and the Soviet Union both held tests during the Cold War –
and debris from the last official U.S. ASAT test in 1985 took 19 years
to de-orbit and is no longer a threat to satellites. Debris from the
Soviet tests is still up there.
The U.S. Space Surveillance Network (SSN) is currently tracking over
19,000 objects. Of these, fewer than 900 are active satellites and
another 2,300 are inactive satellites. But this is just the tip of the
iceberg: given sensor improvements, the United States could track at
least 300,000 more objects that are half an inch and bigger, yet still
not be able to monitor everything surrounding our planet. U.S. officials
worry that a non-tracked piece of debris may unexpectedly crash into a
spacecraft or satellite, wrecking it permanently. What you don’t know
apparently can hurt you.
The piece of debris from the Chinese ASAT test that passed so close to
the Hubble was tracked and U.S. officials decided that in this
particular case, the telescope did not need to be moved. However, in
2008, on five separate occasions other spacecraft had to shift in their
orbits in order to avoid colliding with some debris. This requires using
up some of the precious fuel that the spacecraft take on their missions,
and in many cases interrupting the services and data the satellites
provide.
Of course,
given the alternative, a shortened lifespan is better than complete
annihilation. In February 2009, a U.S. Iridium satellite collided with
an inactive Russian communication satellite, creating almost 900 bits of
trackable debris (and an unknown number too small to track but still
dangerous).
What can
be done about this? Ideally, the debris wouldn’t be created at all. The
United Nations has endorsed a set of voluntary debris mitigation
guidelines presented by a worldwide group of civil space agencies,
including NASA. The United States and several other nations are
implementing these measures. However, more than 40 different countries
currently own or operate satellites so implementation needs to be more
widespread. Meanwhile, the United States is working on improving its
space situational awareness so that it can continue to monitor and track
debris. Finally, abstaining from using destructive ASAT weapons ensures
that damaging debris isn’t created that will be around for eons. With
over 400 satellites on orbit, the United States stands to lose the most
if space becomes a shooting gallery.
--
Victoria
Samson is the Washington Office Director for the Secure World
Foundation, an organization that focuses on the secure and sustainable
use of space.
http://www.swfound.org/.
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