The International Space Station (ISS) has been thrown briefly out of control on when jet thrusters of a newly-arrived Russian research module inadvertently fired a few hours after it was docked to the orbiting outpost, NASA officials say.
The seven crew members aboard - two Russian cosmonauts, three NASA astronauts, a Japanese astronaut and a European space agency astronaut from France - were never in any immediate danger, NASA and Russian state-owned news agency RIA said on Thursday.
But the malfunction prompted NASA to postpone until at least August 3 its planned launch of Boeing's new CST-100 Starliner capsule on a highly anticipated uncrewed test flight to the space station.
The Starliner had been set to blast off atop an Atlas V rocket on Friday from the Kennedy Space Center in Florida.
Thursday's mishap began about three hours after the multipurpose Nauka module had latched onto the space station, as mission controllers in Moscow were performing some post-docking "reconfiguration" procedures, according to NASA.
The module's jets inexplicably restarted, causing the entire station to pitch out of its normal flight position some 400 kilometres above Earth, leading the mission's flight director to declare a "spacecraft emergency," US space agency officials said.
An unexpected drift in the station's orientation was first detected by automated ground sensors, followed 15 minutes later by a "loss of attitude control" that lasted a little over 45 minutes, according to Joel Montalbano, manager of NASA's space station program.
Flight teams on the ground managed to restore the space station's orientation by activating thrusters on another module of the orbiting platform, NASA officials said.
In its broadcast coverage of the incident, RIA cited NASA specialists at the Johnson Space Center in Houston, Texas, as describing the struggle to regain control of the space station as a "tug of war" between the two modules.
At the height of the incident, the station was pitching out of alignment at the rate of about a half a degree per second, Montalbano said during a NASA conference call with reporters.
The Nauka engines were ultimately switched off, the space station was stabilised and its orientation was restored to where it had begun, NASA said.
Communication with the crew was lost for several minutes twice during the disruption, but "there was no immediate danger at any time to the crew," Montalbano said. He said "the crew really didn't feel any movement".
Had the situation become so dangerous as to require evacuation of personnel, the crew could have escaped in a SpaceX crew capsule still parked at the outpost and designed to serve as a "lifeboat" if necessary, said Steve Stich, manager of NASA's commercial crew program.
What caused the malfunction of the thrusters on the Nauka module, delivered by the Russian space agency Roscosmos, has yet to be determined, NASA officials said.
Australian Associated Press