This Friday, ground mission control ordered the current stationed astronaut crew at the International Space Station to head for the escape capsules as a safety precaution in light of a threatening space junk flyby. This is the third time in 12 years an ISS crew had to take this extreme measure.

Graph showing space debris inflation from the past few decades. In 2007, China destroyed one of its satellites with a missile creating 3,000 trackable objects and 150,000 debris particles. In 2009 a Russian and American satellite collided resulting in tonnes of debris. (c) NASA

The space debris in question was barely detected on Friday, offering little advance warning such that the station might be moved, as such the crew, three Russians, two Americans and one Dutch astronaut, were advised to man the two Soyuz escape capsules in case the station was hit. According to NASA, however, the space junk’s trajectory was well beyond that of the space station, posing little threat, but made for an excellent exercise opportunity. Russia’s space agency said the debris had passed the station at a distance of 23km (14 miles) and on Saturday 0238 GMT, the astronauts were given the green light to return to the main space station modules.

“Everything went by the book and as expected, the small piece of cosmos satellite debris passed the international space station without incident.”

“The cosmonauts have returned to performing their previously assigned work,” an official told Interfax news agency.

A similar incident occurred just last June, however the situation was a lot more stressful, compared to the present one, which simply made for a convenient safety exercise. Back then, a piece of space debris flew by the ISS at a mere 335m distance – a red alert was issued then.

NASA currently keeps track of around 22,000 space objects orbiting Earth, but there are some million other space debris which are either too small to track or have yet to be tracked by the agency. These tiny space objects travel at a few kilometers per second, velocities ten times higher than that of bullet, and if eventually one such object were to hit the ISS, it might cause severe damage to the station itself or its instruments. An international standard for handling space junk is currently being discussed to keep the current rate of increase in debris to a minimum, while clean-up solutions, like a giant laser or space janitor satellite, are discussed for immediate deployment.