London, March 13 (ANI): The threat of a possible collision with a piece of space junk made the three crew members of the International Space Station (ISS) to briefly evacuate the station and take shelter in a docked Soyuz spacecraft.
According to a report in New Scientist, NASA said that the threat has now passed and the crew will return to the station, but the last-minute move highlights how difficult it is to determine the paths of space debris that follow certain kinds of orbits.
Tracking data suggested that the debris, a 13-centimetre-wide piece of a spent satellite motor called PAM-D (unrelated to debris from last month's satellite crash), could come about 4.5 kilometers of the station.
That sounds like a safe enough distance, but it was too close for NASA's comfort.
"That's because there was a lot of uncertainty in the measurement due to the elongated orbit of the debris," said Gene Stansbery, NASA's orbital debris programme manager. "They weren't confident of that 4.5-km miss distance," he told New Scientist.
The consequences of a possible collision could have been dire.
"If the debris hit a pressurised module in the station, it could punch a hole in it and cause the module to lose pressurization critical to the crew's survival," Stansbery said.
"If you had something the size and weight of a nickel coin going at 10 km/s - the estimated relative speed between the station and the PAM-D debris -then it has the equivalent energy of a small car at 50 miles per hour (80 km/h). Thirteen centimeters is much larger than that," he added.
According to Stansbery, the possible collision was only discovered on the night of March 11 - not enough time to move the space station away from the debris.
As a result, on March 12, crew members Mike Fincke, Yury Lonchakov and Sandra Magnus were told that they would be taking refuge in the Soyuz, a docked Russian spaceship that could bring the crew back to Earth in case of an emergency on the station.
The three made their way to the Soyuz so they could quickly close the hatches in case the debris damaged the station and they had to undock.
Such evacuations are "very rare," NASA spokesman William Jeffs told New Scientist. (ANI)