How NASA Narrowly Missed a 1.5 Ton Defunct Russian Spy Satellite [VIDEO]

March 29, 2012 came and went and perhaps many can't remember what happened on that day. That's not the case for one NASA project scientists who helped prevent a space telescope from narrowly missing an 1.5 ton Russian defunct spy satellite by a mere 700 feet.

Julie McEnery, the project scientist for NASA's Fermi Gamma-ray Space Telescope received an automatically generated email warning from NASA's Robotic Conjunction Assessment Risk Analysis (CARA) team. The email warned that Fermi was just one week away from an unusually close encounter with Cosmos 1805, a defunct spy satellite from the Cold War which is still speeding around the Earth at 15,000 mph.

"My immediate reaction was, 'Whoa, this is different from anything we've seen before,' " McEnery recalls, according to the NASA statement.

Fermi and Cosmos 1805 have been speeding around Earth at thousands of miles an hour in nearly perpendicular orbits. The two objects were predicted to miss each other by just 700 feet, but satellite operators have learned that they can't be too careful. In February 2009, a dead Russian communications satellite called Cosmos 2251 collided with US commercially-owned satellite Iridium 33 in low-earth orbit, becoming the first known satellite-to-satellite collision in 2009.

The crash made thousands of fragments large enough to be tracked, and they still cause hazards for astronauts aboard the International Space Station (ISS). Fermi has a relative speed of 27,000 miles-per-hour, so a direct hit by the 3,100-pound Cosmos 1805 would release as much energy as two and a half tons of high explosives, destroying both spacecraft and creating a flood of space debris.

Fermi's team was able to calculate how much they needed to move the spacecraft in order to avoid the threat. They selected possible times for the primary maneuver and up to three additional ones just in case.

"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 explained. "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."

After performing the maneuver, Fermi and the 3,100-pound defunct satellite were able to miss each other by a comfortable margin of six miles.

"A huge weight was lifted," McEnery said. "I felt like I'd lost 20 pounds."

Watch Fermi's close all with the Soviet Satellite below: