Wednesday’s Rocket Roundup was a little light on the rockets. There were no launches. Next week is looking better, but we have one story we didn’t want to postpone until then. It’s not a rocket launch, it is, however, launch-related.

Back on July 21, Russia finally launched their Nauka Multipurpose Laboratory Module to the International Space Station (ISS), and the docking was scheduled for July 29. There was an incident after docking the module to the space station. But let’s start with the rendezvous and docking itself, which were also eventful.

Nauka’s propulsion system malfunctioned almost immediately after launch, with the main engines unable to burn for several days as the fuel tank pressures were accidentally mixed. The main engines could not be fired until the pressure dropped to a lower level. The initial burns to raise the module’s orbit for the rendezvous were performed instead by the smaller reaction control thrusters. The main engines finally became operational on July 25 and operated correctly in their planned burns.

The docking itself was sporty as well. The module briefly stopped responding to commands to slow down, and in the last few moments, the ISS crew nearly took over manual control of the docking. That turned out to be unnecessary, and the module completed docking and hard capture in automatic mode. Then the real fun began…

The Nauka module appears to have thought it was still trying to dock after hard capture and fired its thrusters while docked to the ISS at around 16:45 UTC. This caused it to move the entire 440-ton station 45 degrees out of attitude. A leak of some kind was also occurring from the module, as evidenced by clouds of particles observed coming from it.

Luckily, Nauka ran out of propellant, and the thrusters stopped firing. The thrusters were also inhibited from the ground by Russian mission control.

The ISS was out of attitude control for about 45 minutes, and the space station’s correct attitude was recovered with thruster firings from the Zvezda Service Module and Progress MS-17. The Control Moment Gyroscopes, three spinning masses, one for each axis on the ISS’s truss, are normally used to move the station around without the use of thrusters. They were not up to the task so control of the ISS’s attitude was handed over to the thrusters on Zvezda and Progress.

At no point were any ISS crew in danger according to NASA’s Public Affairs Office, but if the situation had gotten worse, they would have evacuated the station. Both the Soyuz MS-18 and the Crew Dragon were powered up and could have departed the station in minutes even with the station moving around due to the loss of attitude control.

The ISS was also out of communication with the ground for a total of eleven minutes because the changed orientation meant the Ku band dish was out of alignment with the TDRS satellites in geostationary orbit.

The Nauka module will also safe its propellant system by firing pyro valves to explosively separate the contaminated and now redundant propellant tanks from the thrusters to prevent further accidental thruster firings. This part, at least, was pre-planned as the module will not be used to help control the ISS’ attitude. Also, it’s now a simpler plan due to the inadvertent thruster firing which used up most of the remaining propellant.

After the tanks are separated, they will be purged with nitrogen. This configuration will still allow a docked Progress vehicle to transfer propellant through the Nauka module to refuel the tanks and engines on the Zvezda module which is used for both orbit raising and station attitude control.

But wait, there’s more! This entire incident had the effect of delaying the planned launch of Boeing’s Starliner spacecraft, originally planned for later today, to the next available opportunity on August 3 at 17:20 UTC. The ISS program directors want some time to fully inspect the station for damage.

All in all, it was a wild and woolly ride. We’re glad that the crew and station are safe, and we hope it stays that way.

More Information

Space Station Stable After Earlier Unplanned MLM Thruster Firing (NASA)