Officials at the U.S. space agency NASA said early Saturday that a number of astronauts residing abroad the International Space Station remain safe, despite earlier warnings suggesting the ISS faced a threat from a large piece of space junk.
Crew members scrambled into an emergency capsule before the large piece of space junk passed by, said NASA. Space agency officials say the large piece of debris is the result of a Russian satellite that was identified by NASA late Friday. Officials say the debris was located far too late to move the space station to safety.
Officials said Saturday that the debris eventually passed the ISS within an estimated nine miles, one of the nearest brushes that space station has had in recent years.
“The Expedition 30 crew aboard the International Space Station received an ‘all clear’ to move out of their Soyuz vehicles after a small piece of a Russian Cosmos satellite debris passed by the complex without incident early Saturday,” read a statement released by NASA.
“Everything went by the book,” NASA spokesman Rob Navias added, saying the station’s controllers followed a “precautionary and conservative” approach by ordering the crew to take shelter.
The space agency, which has increased its presence on social media, tweeted additional details Saturday, saying the space station is the “most heavily shielded spacecraft ever, to protect it from debris.” and that the crew was trained to handle precautionary maneuvers.
The U.S. space agency described the Soyuz capsules as “the crew’s transportation to Earth, for either a normal end of mission, or as a ‘rescue craft.'”
The incident highlights the growing concern that space junk may present greater problems for astronauts in the future. Chinese space officials in 2011 faced criticism, following the launch of a missile into space that eventually destroyed a satellite, shattering it into millions of pieces, each zooming around the Earth at tens of thousands of miles per hour.
NASA estimates that in low Earth orbit (below 2,000 km), orbital debris circle the Earth at speeds of 7 to 8 km/s (15,000 mph). However, the average impact speed of orbital debris with another space object will be approximately 10 km/s; consequently, collisions with even a small piece of debris will involve considerable energy.
While NASA says it is actively tracking some 22,000 pieces of space debris, it noted Friday that there are millions of objects left over from decades of space travel drifting in Earth’s orbit, making it nearly impossible to track every possible piece of space junk. NASA says that the pieces poising a risk to astronauts range from an inch across to large chunks of rockets, defunct satellites or discarded fuel tanks.
The space agency says that space junk is defined as anything from derelict spacecraft and upper stages of launch vehicles to carriers for multiple payloads. The team noted that space junk is created by debris intentionally released during spacecraft separation from its launch vehicle or during mission operations, debris created as a result of spacecraft or upper stage explosions or collisions, solid rocket motor effluents, and tiny flecks of paint released by thermal stress or small particle impacts.
NASA officials also took time to further explain how often space junk impacts the space station and shuttle missions to low-earth orbit. Officials noted that operational spacecraft are often struck by very small debris (and micrometeoroids) routinely with little or no effect. Debris shields can also protect spacecraft components from particles as large as 1 cm in diameter.
The incident comes just one week before an unmanned cargo transport is slated to launch to the space station. National Research Council warned recently that the increasing volume of space debris is endangering the work of the space station and satellites, leading to concerns that space station crews may need to further shield the station from debris.
This is the third time in 12 years that astronauts have had to seek shelter from space junk.