A NASA telescope narrowly escaped a collision with a Soviet-era Russian spy satellite last year, NASA has announced. The close call highlights the dangers of growing space debris around Earth.
The near-collision involved the $690-million NASA Fermi Gamma-ray Space Telescope and the Russian satellite Cosmos 1805 and took place on April 3, 2012. NASA was able to save Fermi, which studies the universe's strongest explosions, by commanding it to fire its thrusters to dodge the collision.
"My immediate reaction was, 'Whoa, this is different from anything we've seen before!' " NASA Fermi project scientist Julie McEnery said in a statement.
NASA learned of the potential for a collision on March 29, 2012, when McEnery received an automatically generated email from the NASA Robotic Conjunction Assessment Risk Analysis team. The report indicated that Fermi and Cosmos would impact in just one week. They knew that Cosmos was moving at a relative speed of 27,000 miles per hour, which meant that both spacecraft would be destroyed if a collision were to take place.
Though NASA predicted that the two objects would miss each other by 700 feet, they remained skeptical, given the fact that some past predictions had turned out to be inaccurate.
"It's similar to forecasting rain at a specific time and place a week in advance," Eric Stoneking, engineer for Fermi at the NASA Goddard Space Flight Center in Greenbelt, Md., said in a press release. "As the date approaches, uncertainties in the prediction decrease and the initial picture may change dramatically."
In the end, the two spacecraft sped past each other at a distance of six miles. The destruction of the Fermi telescope would have been a major loss for NASA and for astrophysics in general. The telescope has been used to capture startling cosmic explosions, confirm the origin of cosmic rays and even investigate dark matter. NASA was ultimately able to save the telescope through a simple thrust maneuver.
"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 debris from Earth has been a growing threat since the launch of Sputnik in 1957. The U.S. has counted around 17,000 objects larger than 10 centimeters, of which around 1,200 are active satellites. A different Russian satellite collided with the U.S. communications satellite Iridium 33 in February 2009, destroying both and creating vast amounts of debris.
NASA released a video of the latest close call, which you can watch below.
