Russian Nauka Module’s Tilting Of International Space Station: How Bad It Got Before Recovery

Russia's Nauka module, which docked with the International Space Station (ISS) on 29 July, briefly tiled the low-Earth orbital station much more than first indicated.

According to an update on the incident by the National Aeronautics and Space Administration (NASA), the space station went about 540 degrees "out of attitude" before returning to normalcy. Whereas soon after the incident, NASA had stated 45 degrees out of attitude.

"@space_station (ISS) was 45° out of attitude when Nauka's thrusters were still firing & loss of control was discussed with the crew. Further analysis showed total attitude change before regaining normal attitude control was ~540°," NASA's latest Twitter update said.

One revolution makes up 360 degrees. Adding another 180 degrees, or half a revolution, takes the total to 520 degrees. Therefore, the station went around and then some, to end up upside down. It then had to be turned around 180 degrees to bring it back to position, NASA flight director Zebulon Scoville told the New York Times.

It was the first time that Scoville had declared a "spacecraft emergency" since he took up the job seven years ago.

Despite the mishap, the crew — three American astronauts, two Russian cosmonauts, and two astronauts from Japan and France — were said to be never in any danger, and the space station is in "good shape & operating normally".

Nauka, "science" in Russian, is a multipurpose laboratory module for the Russian segment of the ISS. It was developed to conduct scientific experiments and to expand the overall functionality and capabilities of the Russian presence on the station. It will be able to more than double the number of experiments conducted on the module.

The new Russian module was launched on board a Proton-M heavy launch vehicle from the Baikonur Cosmodrome on 21 July to replace the Pirs module. Pirs, which was used as a docking module for the Russian Soyuz crewed and Progress cargo spacecraft, as well as for spacewalks until last year, was undocked from the station on 26 July. It lived at the ISS for two decades before it was taken off to be burnt up in the Earth's atmosphere.

On 29 July, over three hours after it docked to the nadir port of the Zvezda service module of the ISS Russian segment, the Nauka module inadvertently began firing its thrusters, causing the space station to move out of orientation temporarily. It prompted the implementation of recovery operations on board to stabilise the situation.

"The ISS Progress 78 cargo ship that is docked to the Poisk module on the zenith side of the International Space Station's russian segment was brought into play by the Russian flight control team, who responded very quickly. The Progress thrusters fired and attitude has now been regained. So the station is back in a normal attitude configuration …", NASA explained from its mission control in Houston, Texas, after the incident.

The flight director of the space station's Russian segment attributed the misbehaviour to a software error. "Due to a short-term software failure, a direct command was mistakenly implemented to turn on the module's engines for withdrawal, which led to some modification of the orientation of the complex as a whole," Vladimir Solovyov said in a statement.

However, the head of the Russian space agency Roscosmos said in an interview with Radio Komsomolskaya Pravda that a "human factor" could have been involved. "Perhaps one of the operators simply did not take into account that, perhaps, the control system of the unit itself will continue to adjust itself in space," Dmitry Rogozin said (Google translation of the Russian transcript).

Noting that the ISS is "quite a delicate facility", Roscosmos executive director for manned space programs Sergei Krikalyov reportedly told the Rossiya-24 TV Channel that a special commission would look into the causes and consequences of the incident. No damage to the station has been reported as yet.

Meanwhile, Nauka's integration into the ISS is in progress and is estimated to take more than six months to complete. During this time, about 10 spacewalks are planned to be implemented, in addition to the redocking of the Yuri Gagarin (Soyuz MS-18) with Nauka and, consequently, freeing up of the Rassvet module for docking with the planned Soyuz MS-19 spacecraft.

The MS-19 is scheduled for launch from Russian soil on 5 October. In preparation to receive it on the space station, the Russian Mission Control Center is set to carry out an orbital altitude correction of the ISS on 19 August.

This week, Roscosmos cosmonauts Oleg Novitskiy and Pyotr Dubrov are in the process of unloading the module and sorting out the equipment.

Cosmonaut Novitskiy has shared a video of his brief tour of Nauka. A more detailed tour is set to follow as well.

Russia will be happy to see Nauka settling into the ISS, as the module's misfortunes go back a long way. The Nauka has been called the "long-suffering module" because of its prolonged struggles. It was conceived back in the mid-1990s as a backup for what became the first module on the ISS. It was built so that it could step in to take the Zarya module's place if it was lost in a launch failure.

Not required to serve its primary role as a backup module after Zarya's success, it was proposed that the Nauka be repurposed into a laboratory module for the ISS. It was built and set for launch in 2007. But repeated launch delays on account of funding and technical challenges set the Russian "science" module launch back by over a decade. It finally took off towards the end of July 2021.

Still, even after reaching the orbit, Nauka required several manoeuvres for orbit correction over days after it faced propulsion issues. And then, after successfully docking with the ISS, came the accidental thruster fire that tilted the space station out of orientation.

However, ever since the situation has been brought under control, Nauka — as well as the space station — appear to be doing fine.

Russia has previously expressed concern about the ageing space station and deliberated over its future with the orbital outpost. In a recent meeting hosted by Roscosmos, officials said: "further operation of the ISS Russian segment after 2024 creates additional risks".

Russia is mulling the development of a Russian Orbital Service Station (ROSS), which will be a crewed space complex in low-Earth orbit. Just as for NASA, the ISS is a stepping stone to space missions farther out, Roscosmos sees ROSS fitting into its plans for future missions centred around the Moon and Mars.