A Russian module docked to the ISS (International Space Station) on July 29 began shooting its thrusters hours later, momentarily throwing the station out of its regular orientation and forcing NASA to postpone a commercial crew test flight scheduled for July 30. At 9:29 a.m. Eastern, the station’s MLM (Multipurpose Laboratory Module), or Nauka, docked with the station’s Zvezda service module. The self-propelled module neared the station and docked without incident.
Nauka began firing its thrusters at 12:34 p.m. Eastern for unclear reasons. Eight minutes later, the station lost attitude control, drifting up to 45 degrees out of alignment until being stopped by thrusters on Zvezda as well as a Progress cargo spacecraft. At 1:29 p.m. Eastern, Russian operators were able to turn off Nauka’s thrusters, and the station’s attitude control was restored. While the issue was significant, it did not present a danger to the seven individuals on board. In a media interview, just several hours after the incident, NASA ISS program manager Joel Montalbano stated, “There was no obvious threat to the crew at any time.” Flight controllers, he continued, are trained for situations like these frequently and acted rapidly to remedy the issue.
Both Houston and Moscow station controllers were still trying to figure out what caused Nauka’s thrusters to fire. However, Montalbano said Russian operators had “inhibited” the thrusters so they wouldn’t fire again. Although the consequences of the thruster firings are still being studied, the station was moving at a pace of up to half a degree for every second, largely in pitch, which he claimed made him “not too concerned.” Montalbano said he didn’t know how the exact amount of propellant was required to regain attitude control, but it didn’t deplete the station’s reserves. He stated, “We didn’t utilize anything that I might be concerned about.” “Obviously, we needed extra propellant, but it’s not something I’m concerned about.”
Around the time Nauka was firing its thrusters, station crew members reported seeing some debris floating away from the station. The station appears to be undamaged, and Montalbano speculated that the crew might have observed “flakes or something” from thrusters themselves. While controllers labored to reconfigure Nauka, engineers intended to complete a “quick look” evaluation of the station by the close of the day on July 30. Around the time the thrusters fired, Russian cosmonauts on the station were ready to open the hatch to a module but had not yet reached the module.
Nauka was launched aboard a Proton rocket on July 21. Shortly after reaching orbit, the module experienced various technical issues, including a glitch with its propulsion system, which raised concerns about its ability to dock safely with the station. Russian controllers addressed the concerns and proceeded with the extraction of the Pirs airlock module that had taken up residence in the port where the Nauka was scheduled to dock on July 26.