This artist's impression shows the Upper Atmosphere
Research Satellite, launched on Sept. 15, 1991, by the space
shuttle Discovery (image from NASA)
NASA has recently announced that an out-of-control, retired
satellite will come crashing into the earth's surface "sometime"
towards the end of September. Furthermore, the satellite, which
is about the size of a school bus and weights over 6 tonnes (6.6
tons), will impact the earth in an unknown location between
Canada and South America. The exact time and location will
remain a mystery until two hours before the event, and that's
with six thousand miles (10,000 km) of uncertainty.
"It is too early to say exactly when UARS will re-enter and
what geographic area may be affected," states NASA.
The Upper Atmosphere Research Satellite (UARS) will come
crashing back to Earth after it was placed into orbit almost
twenty years ago. Although the spacecraft will break into pieces
during re-entry, not all of it will burn up in the atmosphere
beforehand. It is anticipated that 26 large fragments of the
UARS satellite will actually fall to Earth, in a rain of debris
altogether weighing about 1,170 pounds/532 kg (the largest
weighing 300 pounds/150 kg). Though it is impossible to predict
the exact impact zones, NASA estimates the debris footprint will
be approximately 500 miles (800 km) long.
The US$750 million UARS satellite will be the largest NASA
satellite to make an uncontrolled dive back to Earth in years.
However, NASA assures that the risk to public safety or property
is extremely low. "Throughout the entire 54 years of the Space
Age there has been no report of anyone being injured or impacted
by any re-entering debris," said Nick Johnson, the chief
scientist of NASA's Orbital Debris Program at the agency's
Johnson Space Center in Houston. That's keeping in mind that
during this time, on average, one piece of debris has fallen
back to Earth each day.
UARS was originally put into orbit in 1991 to collect data on
the ozone layer and measures 35 feet (10.7 meters) long and 15
feet (4.5 m) wide. In 2005, NASA decommissioned the spacecraft,
causing it to make a six-year plunge back to Earth. NASA will
post constant updates before the anticipated re-entry of UARS,
which will come directly from the Joint Space Operations Center
of U.S. Strategic Command at Vandenberg Air Force Base,
California. The center works 24/7 detecting, identifying and
tracking all man-made objects in Earth orbit, including space
junk.
NASA also warns people to not touch any pieces of UARS debris
and to contact a local law enforcement official for assistance.
You can read updates on the falling UARS on the
NASA website.
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