In July, Russia finally got its new Nakua laboratory module into orbit and attached to the ISS. Unfortunately for the crew and the space station, shortly after being attached an inadvertent thruster firing in the laboratory module pushed the entire space station off-axis. Another unplanned thruster firing by Russian spacecraft happened this week that pushed the ISS out of proper orientation again.
The latest accidental thruster firing happened on October 15 and is the second incident in less than three months. The spacecraft that accidentally fired its thrusters this time wasn’t the laboratory module. Rather it was the Soyuz MS-18 spacecraft that would bring a Russian cosmonaut, actor, and film director back to Earth tomorrow. In this incident, flight control purposely activated the spacecraft thrusters at 5:02 AM EDT as part of a planned test before departure.
However, NASA officials say the thruster firing continued after the test ceased, resulting in a loss of attitude control for the ISS at 5:13 AM. NASA says the crew aboard the ISS was never in any danger. Within 30 minutes, flight controllers were able to regain attitude control, and the space station is currently stable. NASA added that the crew was awake during the event.
The ISS was briefly pushed from its normal orientation by 57 degrees. Right now, there is no clear cause of what led to the thrusters firing for longer than they were intended. It’s also unclear why the thrusters stopped firing on their own. NASA believes the thrusters on the Russian spacecraft stopped firing on their own because they had reached their propellant limit.
NASA says Russian flight controllers are checking into the cause of both the inadvertent firing and the unexplained cessation of the thrusters via data analysis. Back in July, Russia blamed the inadvertent firing on a glitch in the software. The MS-18 spacecraft is still expected to leave the ISS today.