NASA created a video of Fermi's near miss with space junk to illustrate how high the risk of a space collision really was. [
Fermi mission scientists first learned of the space collision threat
on March 29, 2012 when they received a notice that the space telescope
and Cosmos 1805 would miss each other by just 700 feet. The mission team
monitored the situation over the next day and it became clear that the
two spacecraft, traveling in different orbits, would zip through the
same point in space within 30 milliseconds of one another, NASA
officials said.
"My immediate reaction was, 'Whoa, this is different from anything
we've seen before!'" NASA's Fermi project scientist Julie McEnery said
in a statement.
The Russian space junk
was travelling at a speed of 27,000 miles per hour in relation to
Fermi. If it had smashed into the space telescope the explosion of the
two spacecraft would have released "as much energy as two and a half
tons of explosives," NASA officials said
"It was clear we had to be ready to move Fermi out of the way, and
that's when I alerted our Flight Dynamics Team that we were planning a
maneuver," McEnery added.
After making those calculations, scientists started planning to fire
Fermi's thrusters specifically designed to move the satellite out of the
way if these situations arise.
"It's similar to forecasting rain at a specific time and place a week
in advance," Eric Stoneking, the attitude control lead engineer for
Fermi at NASA's Goddard Space Flight Center said of predicting these
kinds of impacts in a statement. "As the date approaches, uncertainties
in the prediction decrease and the initial picture may change
dramatically."
The two spacecraft ultimately missed each other by 6 miles when they passed one another on April 3, 2012.
"The maneuver, which was performed by the spacecraft itself based on
procedures we developed a long time ago, was very simple, just firing
all thrusters for one second," Stoneking said. "There was a lot of
suspense and tension leading up to it, but once it was over, we just
sighed with relief that it all went well."
"A huge weight was lifted," McEnery said. "I felt like I'd lost 20 pounds."
Space junk has been a growing threat to satellites and manned
spacecraft in orbit, and collisions do occur from time to time. Last
month, the European Space Agency held its sixth conference dedicated to
combating the space junk threat in Darmstadt, Germany.
In February 2009, another dead Russian satellite slammed into the
U.S. communications satellite Iridium 33 in a space collision that
spawned vast clouds of debris, one along each craft's orbit. In 2007,
China intentionally destroyed a defunct weather satellite in an
anti-satellite test.
NASA tracks 17,000 objects larger than 4 inches across in orbit above
the Earth every day. Only 7 percent of the objects tracked are
currently active satellites.
The Fermi telescope — launched in 2008 — searches the sky for signs
of dark matter, black holes and spinning pulsars by seeking out sources
of gamma-ray bursts, the brightest flashes of light in the universe
since the Big Bang.
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