Playing it safe, the seven-member crew of the International Space Station moved into the U.S. segment of the outpost Friday, closed hatches and window shutters and stood by while Russian flight controllers vented helium pressurization lines in the newly arrived Nauka lab module.
Because of earlier problems with the module's propulsion system, the crew was taking no chances, but high-pressure helium in lines used to pressurize Nauka's propellants was safely vented overboard. Moments later, station cosmonauts Oleg Novitskiy and Pyotr Dubrov opened a final hatch and floated into the roomy new addition.
"Congratulations for a successful venting," station commander Akihiko Hoshide radioed flight controllers in Houston and Moscow. "We'll stand down from the current posture."
The 44,000-pound Nauka multi-purpose laboratory docked with the station's Russian Zvezda module Thursday. But a software error resulted in unexpected thruster firings three hours later, while the lab was out of contact with Russian flight controllers. The error pushed the space station out of its normal orientation, or "attitude."
The unwanted motion prompted thrusters in the Zvezda module to fire in an attempt to counteract the push from Nauka's jets. Thrusters in a Progress cargo ship also joined in to provide more strength.
NASA flight director Zeb Scoville later tweeted the result was a "force fight" between Nauka and Zvezda's thrusters. Given the orientation of the modules and the relative strengths of the thrusters, "the ISS brought a knife to a gun fight."
"Reports of ISS only being 45 degrees out (of normal orientation) were premature," he said. "We proceeded to do headstands and cartwheels. Olympic judges would be proud."
He said the station "got about as far out of attitude as you can. Eventually won the force fight and returned to straight and level."
In any case, with the propellant pressurization lines now evacuated, the cosmonauts were clear to press ahead with the new module's initial activation and outfitting.
Reflecting on the work to recover from the loss of attitude control, Scoville tweeted "Never have I ever: 1) been prouder of the team that sits in MCC (mission control) and lives on @Space_Station, 2) had to declare a spacecraft emergency until now, 3) been so happy to see all solar arrays + radiators still attached."
Going into Nauka's docking, NASA had been looking forward to the launch of an Atlas 5 rocket Friday carrying Boeing's Starliner crew capsule on a second unpiloted test flight to the space station. With a successful flight test, Boeing hopes to begin launching astronauts by the end of this year or early next.
But given the drama of Nauka's arrival and initial uncertainty about the health of the module, NASA managers opted to delay the Starliner launch. The flight has tentatively been reset for launch on Tuesday, at 1:20 p.m. EDT.
In the meantime, rocket-builder United Launch Alliance hauled the booster and its payload off its Cape Canaveral launch pad and back to a processing facility to keep it out of stormy afternoon weather.