As the six-person Station slept last week, a pressure/atmosphere leak appeared in the Soyuz MS-09 crew vehicle attached to the Station. The leak occurred when a very small breach (only 2 millimeters) opened up in the Soyuz Orbital Module’s hull, allowing a very small amount of atmosphere/pressure to leak into space. The leak was so small that NASA and Roscosmos did not wake the crew when the leak first appeared.
The Russians quickly devised temporary and more permanent fixes for the leak – both of which were implemented. The crew is in no danger, and there appears to be no issues with Soyuz MS-09’s continued life at the Station and ability to return its three crewmembers safely to Earth in December. The main drama relates to the root cause of the hole.
The leak and fixes:
Once the crew was awakened as normal, Mission Control Center – Moscow (MCC-M) and MMC-H (Houston) immediately set the crew to work tracking down the source of the leak.
The leak itself was – relatively speaking – very small and non-life threatening, with communications to the crew noting that it would take 18 days at the maximum leak rate to deplete the oxygen tank reserves on the Station. Meaning the leak was not an immediate threat to the crew or the Station.
The leak was quickly traced to the Russian side of the Station, and further examinations identified the leak to be inside the Soyuz MS-09 crew vehicle which brought three astronauts to the Station in June 2018.
When the leak was found, it was first reported by the crew to be from two small holes in the Soyuz MS-09’s Orbital Module (the part that contains the physical docking mechanism to connect Soyuz to the Station).
However, later in the day, an official NASA statement said that the leak was via only one hole in the Soyuz MS-09’s Orbital Module – a hole that was only 2 millimeters in diameter.
Shortly after finding the hole, the crew took photos for ground crews to review. At the same time, the Russian crewmembers used Kapton tape to temporarily seal the breach/leak – a band-aid until a more permanent solution was found and a temporary fix that at first only slowed the leak rate.
After the tape was applied, reports varied regarding ISS pressure – with some reports from the crew noting a stabilization of pressure inside the international complex and others continuing to show a slower leak.
Within hours, the Russians had devised a permanent fix using sealant, tape, and medical patches.
There was some initial disagreement among the crew (as well as between NASA and Roscosmos) in terms of implementing the permanent fix so quickly, with ISS Commander Drew Feustel (NASA) wanting to hold off on the permanent fix until the ground could review the idea while Roscosmos wanted to proceed with the sealant/patch/tape fix immediately.
Ultimately, Roscosmos and the Russian crew proceeded with the fix.
The sealant – as of writing – appears to have worked and stopped the leak completely. However, application of the final aspects of the repair (the application of patches and tape) have been left until tomorrow to allow the sealant of fully set and harden during the crew’s “overnight” sleep period.
By the early afternoon (EDT), NASA released an ISS daily update regarding the leak, shedding more light on exactly what happened and how the day’s events unfolded.
“Overnight, ground teams noticed a decreasing trend in ISS stack pressure at approximately 1800 GMT (6PM Central). Initial indications showed a leak rate of approximately 0.8 mmHg per hour, slightly higher than the maximum specification leakage rate of 0.5 mmHg per hour.
“Throughout the night, the leak rate increased in magnitude to approximately 4 mmHg/hr. Crew performed actions to isolate the location of the leak by closing hatches between modules and utilizing the Ultrasonic Leak Detector before isolating the location to the Soyuz [MS-09] orbital module behind the Soyuz toilet.
“The hole located was described as approximately 2 mm in diameter but did not appear to be a through hole as metal was described to be behind the hole. Crew placed kapton tape over the hole temporarily which has stabilized the leak rate to below spec leakage.
“Crew is in work to use a Russian patch kit to place sealant within the hole and a patch over the hole. Ground teams will monitor ISS stack pressure following repair.”
The cause of the leak is still under investigation, and no definitive answer to why this occurred has been released yet – though it was initially believed to be a result of an MMOD (Micro Meteoroid Orbital Debris) strike to Soyuz with MCC-M not suspecting metal fatigue on the Soyuz itself in the initial hours of the investigation.
NASA appeared to make a mistake in releasing the photos of the hole on their recent Space To Ground video update, as they later deleted the video and edited the footage to remove the photos. However, this came only after numerous people had screenshot the photos – mainly in part due to the space community noticing it did not appear to be an MMOD strike – and saved the video for reuploading to social media.
— Emi (@Noemi_Cogoni) August 31, 2018
The publication of the photos also confirmed some internal chatter ahead of the photos being shown than the hole looked nothing like an MMOD strike and was “suspect”. That was later backed up by sources in the Russian media speaking of a drill hole.
Amazingly, the head of Roscosmos, Dmitriy Rogozin confirmed the source information and went further, claiming he wasn’t sure if the hole was caused by an engineer on the ground, or someone in space – the latter being almost unthinkable.
“We are checking the Earth-bound version, but there is another version which we are not ignoring: intentional action in space. There are traces made of several attempts to drill a hole,” Rogozin – who famously told NASA to use a trampoline to send its astronauts to the ISS when he was in Russian politics – was quoted as saying to RIA SCIENCE and accurately translated by USAF Russian language analyst Robinson Mitchell for NSF.
“We are able to narrow down the cause to a technological mistake of a technician. We can see the mark where the drill bit slid along the surface of the hull. But where did it happen? On Earth or in orbit? It is a matter of honor (to understand if it is) an intentional action. We want to find out the full name of who is at fault – and we will.”
An investigation is currently taking place and is expected to be complete by the end of the week.
NASASpaceflight will update this article with more information as it becomes available. *Live updates and discussion on this situation can be found here*
What if the leak/puncture had been worse or been in the Soyuz’s Descent Module:
Despite the fact that this leak – right now – was minor and appears to have been easily repaired, the question arose from many observers of exactly what plans are in place to ensure a Station crew’s successful and safe return to Earth should one of the two Soyuz MS-series crew vehicles become disabled and unable to return crew.
Right now, the Soyuz is the only operational crew transportation vehicle for the ISS.
In a generic, non-specific situation, two options for crew return exist.
One would be to launch a crew Soyuz completely without crew to replace the disabled Soyuz.
This has been done once before by Russia (then the Soviet Union) when they launched the Soyuz 34 crew vehicle uncrewed to the Salyut space station to provide its resident crew with a reliable return vehicle after Soyuz 33 suffered an engine failure.
Roscosmos announced on their Twitter feed that Soyuz MS-11 is at the launch site in Baikonur, as is Soyuz MS-10 – though both are present as part of their standard launch processing timelines.
The other option would be for the next three immediate Soyuz MS-series launches to have their crew sizes reduced from three to two and each crew member from the defunct Soyuz come back one at a time on those next three successive Soyuz missions.
This plan would greatly mirror the plan NASA and Roscosmos put in place in July 2011 for the final Space Shuttle flight.
Under that plan, should Atlantis have become disabled during STS-135, her four-person crew would have remained on the Station while Atlantis would have been remotely undocked from the Station and sent for a destructive dive into Earth’s atmosphere.
Atlantis’ crew would then have rotated down on successive Soyuz flights over the next year.
In the present case with Soyuz MS-09, it has not remotely been hinted at that such contingency scenarios are needed because the repaired leak is in the Soyuz’s Orbital Module and not the critical Descent Module – the part that carries and protects the crew through reentry and landing.
Nonetheless, if the leak were found in the coming days to be worse than thought or found to have fundamentally compromised the overall Soyuz MS-09’s systems/structure (both unlikely scenarios as of publication), the answer would be the implementation of one of two contingency crew return plans.
Under the first scenario, the Soyuz MS-09 crew would remain on the Station while Soyuz MS-10 is launched completely uncrewed to replace the MS-09 Soyuz.
This would greatly shuffle the overall ISS crew manifest and Expedition timelines but preserve the MS-09 crew’s ability to return home together.
The other option would be to launch Soyuz MS-10 as scheduled with its 2-person crew.
Soyuz MS-10 is already a two-person only launch, so one MS-09 crewmember would come back (three months later than their prime mission duration) on Soyuz MS-10.
— РОСКОСМОС (@roscosmos) August 30, 2018
Soyuz MS-11 and MS-12 would then have their three-person crews reduced to two-person crews, and the remaining two MS-09 crew members would come down on those two flights six months and nine months later than planned, respectively.
The other possibility, though much more remote for this particular case, would be if SpaceX’s crewed demo – DM-2 – remained perfectly on schedule for April 2019 and was not expanded to a 6 month flight (as NASA has now hinted is a possibility under review).
If DM-2 remained at 14-day crewed test flight with just two astronauts, then the final two Soyuz MS-09 crew could potentially return on Dragon – though this would be far less likely given continued schedule uncertainty for Commercial Crew vehicles at this point.