Crew aboard the International Space Station (ISS) prepared for the worst overnight, piling into escape craft as their temporary home repeatedly flew into a mysterious cloud of space junk.
Experts think it may have been created by a Russian missile strike on a defunct Soviet spy satellite - eerily similar to the plot of Hollywood blockbuster Gravity.
The ISS first passed the cloud of junk just after 8pm Monday (NZ time), Russian news agency TASS reported. It orbits the Earth every 90 minutes, the extreme speeds meaning any collision has the potential to be catastrophic.
Cosmonauts on board took shelter in an attached Soyuz MS-18 craft, US media reported, while astronauts climbed into the Space Crew Dragon capsule.
The cloud - later tracked by a radar based in New Zealand - was situated just above the ISS's orbit at 400km above the ground north of Russia, inside the Arctic Circle, right where a Russian spy satellite Kosmos-1408 should have been at the time.
Seradata, a space data analysis company, said Kosmos-1408 was previously orbiting "a bit higher than ISS but not much".
US Space Command confirmed the strike, saying it created more than 1500 pieces of new debris large enough to be tracked, and countless smaller pieces.
"This test will significantly increase the risk to astronauts and cosmonauts on the International Space Station as well as to other human spaceflight activities," spokesperson Ned Price said at a briefing, US media reported.
"Russia’s dangerous and irresponsible behavior jeopardizes the long-term sustainability of our outer space and clearly demonstrates that Russia’s claims of opposing the weaponisation of space are disingenuous and hypocritical."
A Russian on board the ISS said the incident hadn't created tensions with his European and American colleagues.
"Friends, everything is regular with us! We continue to work according to the program," said Anton Shkaplerov, one of two cosmonauts currently at the ISS.
The ISS is able to be moved slightly to avoid space junk - a week ago it did so to avoid a piece created by a Chinese anti-satellite test conducted in 2007.
It's now in the 'green zone', and no longer in danger.
Previous near misses have been tracked by LeoLabs' Kiwi Space Radar, which also detected the debris field "near [the] expected location" of Kosmos-1408, still in orbit.
"Our initial data shows at least 30 unique objects detected… The objects currently span a distance range of ~40km as viewed from our radar sites."
In 2007 Hollywood hit Gravity, the ISS is destroyed when it runs into a cloud of debris created when the Russians destroy a defunct spy satellite. Kosmos-1408 was indeed a spy satellite - launched in 1982 when Russia was part of the Soviet Union.