A high-tech orbiting United States telescope nearly missed a potentially disastrous accident with a Soviet-era Russian spy satellite last year --- underscoring the growing threat of orbital debris around Earth.
The $690 million Fermi Gamma-Ray Space Telescope, which studies the most powerful explosions in the universe, narrowly avoided colliding with the defunct 1.5-ton Cosmos 1805 reconnaissance satellite on April 3, 2012, space agency officials revealed earlier this week.
Engineers commanding Fermi were able to fire the orbiting lab's thrusters in time to dodge away from the out-of-control Russian craft.
Fermi mission scientists at the National Aeronautics and Space Administration learned of the looming strike March 29 last year, when they received notice the space telescope and Cosmos 1805 would miss each other by just 700 feet (213.4 meters).
The mission team then began monitoring the two crafts more intently and calculated the satellites, traveling in different orbits, would zip through the same point in space within 30 milliseconds of each other, according to a report by Space.com
"My immediate reaction was, 'Whoa, this is different from anything we've seen before," Fermi project scientist Julie McEnery said in a statement.
The Russian space junk was travelling at an orbital speed of 27,000 miles per hour (43,452 km/h) in relation to Fermi's rate of travel, so If it had smashed into Fermi, the resulting explosion would have released "as much energy as two and a half tons of explosives," NASA officials said.
Therefore, said McEnery, "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.
After running more calculation, scientists ended up firing Fermi's maneuvering thrusters in a one-second burst and successfully changed the telescope's trajectory enough to avoid a crash.
The two spacecraft ended up missing each other by about 6 miles (9 km),
"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," said Eric Stoneking, the attitude control lead engineer for Fermi at NASA's Goddard Space Flight Center. The maneuver itself, he added, was "based on procedures we developed a long time ago, was very simple."
Space junk is understood as a growing risk to satellites and manned spacecraft in orbit and collisions have happened from time to time.
In February 2009, another dead Russian satellite slammed into the U.S. communications satellite Iridium 33 and the resulting explosion left large debris clouds along each craft's orbit.
NASA tracks 17,000 objects larger than 4 inches (10 cm) across orbiting the planet, while only about 7 percent of those objects are currently active satellites.
Launched in 2008, the Fermi telescope searches the sky for signs of dark matter, black holes and spinning pulsars by following bursts of gamma rays, the brightest flashes of light in the known universe.
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