Roscosmos boss: Soyuz pressure leak caused by ‘technological error’

Cosmonaut Sergei Krikalev, left, and Roscosmos Director General Dmitry Rogozin, center, discuss the leak at the Russian mission control center in Korolev, Russia. Credit: Roscosmos

Last week’s depressurization event at the International Space Station may have been caused by human error, not a micrometeoroid impact, Roscosmos boss Dmitry Rogozin told Russian media.

At about 23:00 UTC Aug. 29, 2018, ground controllers in Houston and Moscow noticed the pressure aboard the ISS dropping. While cause for concern, the NASA-described “minute pressure leak” was slow enough that the six-person Expedition 56 crew was allowed to continue sleeping. At its maximum rate, the station had “weeks” of air left. Once awake on Aug. 30, the crew began troubleshooting the problem.

Soyuz MS-09, left, is docked to the Rassvet module. The leak origonated from the upper section of the sapcecraft. Credit: NASA

The source of the pressure drop was isolated to a two-millimeter “microcrack” in the orbital module—the upper section—of the three-part Soyuz MS-09 spacecraft near the vehicle’s toilet and covered by fabric. NASA and Russian officials stressed the crew was in no danger.

The hole was covered first by a temporary application of Kapton tape, which slowed the leak, and more permanently via an epoxy-based sealant.

While the incident on the ISS was apparently solved, a commission on the ground was formed to investigate the cause of the pressure leak. Many speculated that it could have been a micrometeoroid strike. However, Rogozin, the director general of the Roscosmos state-run space corporation told reporters otherwise.

“We are considering all the theories,” Rogozin said. “The one about a meteorite impact has been rejected because the spaceship’s hull was evidently impacted from inside. However it is too early to say definitely what happened.”

Rogozin said the microcrack seemed to have been caused by a “faltering hand,” and was a “technological error” by a specialist.

“It was done by a human hand—there are traces of a drill sliding along the surface,” Rogozin said. “We don’t reject any theories.”

The two-millimeter-wide hole was found on the orbital module of the Soyuz MS-09 spacecraft. Credit: NASA

According a Sept. 3 RIA Novosti report, an industry source said the hole was likely formed when an employee of the spacecraft’s manufacturer, RSC Energia, made an “error,” drilling a hole in the internal hull of the module before sealing the crack with a “special glue.” As such, the leak was not detected during pressurization tests before integrating the spacecraft with the launch vehicle.

Soyuz MS-09 was ultimately given a clean bill of health and launched June 6, 2018, with Russian cosmonaut Sergey Prokopyev, European Space Agency astronaut Alexander Gerst and NASA astronaut Serena Aunon-Chancellor.

“However, [once in orbit], the glue dried and was squeezed out, opening the hole,” a second source told RIA Novosti.

Rogozin told reporters the investigation commission is looking into whether the hole formed because of negligence or was deliberate, according to RIA Novosti.

The ultimate solution was to fill the hole with an epoxy sealant. Credit: NASA

Soyuz MS-09 is currently docked to the Rassvet module and is expected to remain attached to the ISS until mid-December. Prokopyev, Gerst and Aunon-Chancellor are expected to return to Earth using that spacecraft. The hole, should its repair hold, is not expected to impact landing procedures as it is in a part of the craft that does not return to Earth.

During the Aug. 30 repair process, Expedition 56 commander and NASA astronaut Drew Feustel was uncomfortable with the plan and requested more time, 24 hours, to allow teams on the ground to test the procedure.

Feustel is the commander of the space station itself. However, the incident was on the Soyuz MS-09 spacecraft, of which Russian cosmonaut Sergey Prokopyev was the commander.

“I would really like to see a test of that, somehow, on the ground before we do a test up here and see if it’s going to work,” Feustel said. “We sort of feel like we’ve got one shot at it and if we screw it up, then the implications are one of these vehicles is going home, or that vehicle is going home, sooner than later.”

While Moscow and the two cosmonauts waited an hour or so, the decision was made to go ahead with the epoxy solution. Once applied at around 16:30 UTC Aug. 30, a small bubble appeared over the hole, but the pressure leak appeared to have stopped. The crew was instructed to let it set overnight. According to Tass, a second layer of the sealant was added on Aug. 31, and the pressure continued to hold stable.

Rogozin said it is a matter of honor for RSC Energia to “find the one responsible” and to find out whether it was an accident or deliberate and where it was done, be it on the ground or by one of the crew members in orbit.

“It is essential to see the reason, to learn the name of the one responsible for that,” Rogozin said. “And we will find out, without fail.”

NOTE: While this article was written by Derek Richardson, it was originally published at SpaceFlight Insider. Feel free to head over there to read all the stuff they write about!