The six-person Expedition 56 crew aboard the International Space Station had to troubleshoot what NASA described as a “minute pressure leak," which was detected in the orbiting complex by ground controllers in Houston and Moscow.
According to the U.S. space agency, the first signs of a leak were detected around 23:00 UTC Aug. 29, 2018, while the crew was still in their scheduled sleep period. However, the decision was made to allow the Expedition 56 crew to continue sleeping as they were in no danger and had “weeks of air” left in reserves at the rate the hole was letting out air.
“When the crew was awakened at its normal hour this morning, flight controllers at Mission Control in Houston and at the Russian Mission Control Center outside Moscow began working procedures to try to determine the location of the leak,” NASA said in a statement, Aug. 30.
According to NASA, the leak hat been isolated to a hole about two millimeters in diameter in the orbital module—the upper section—of the Soyuz MS-09 spacecraft, which was attached to the Rassvet module on the Russian said of the station. When the crew found the hole, Kapton tape was applied over the hole to slow the leaking.
While the current commander of the ISS is NASA astronaut Drew Feustel, the incident was on the Soyuz MS-09 spacecraft, of which Russian cosmonaut Sergey Prokopyev was the commander.
The initial plan was to have the cosmonauts fill the hole with an epoxy sealant. However, Feustel was uncomfortable with the plan and requested more time, 24 hours, to allow teams on the ground to test the procedure.
"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. The cause of the hole has not yet been determined.
The Expedition 56 crew includes Feustel, NASA astronauts Ricky Arnold and Serena Aunon-Chancellor, European Space Agency astronaut Alexander Gerst and Russian cosmonaut Oleg Artemyev and Prokopyev.
Soyuz MS-09 was used to bring Prokopyev, Aunon-Chancellor and Gerst to the outpost in June 2018. They are scheduled to land in that spacecraft in December 2018. The vehicles orbital module, where the leak was located, does not return to Earth and is jettisoned before reentry.
According to NASA on Aug. 31, the station's cabin pressure was holding steady. The station's crew continued the remainder of that day performing science experiments and preparing for the arrival of the Kounotori 7 spacecraft and two spacewalks based out of the Quest airlock on the U.S. side of the outpost. These events will take up the middle-to-late part of September.