The Crew of the ISS has Found the Source of the Station’s Air Leak

It’s no secret that the International Space Station (ISS) has had a problem with leaks for more than a year. While pressure loss is a perpetual issue, officials noticed an increase last September, which became more serious over the past summer. As of August, the crew began a hard-target search for the source of the leak, eventually narrowing it down to the Zvezda module in the Russian section.

Thanks to an ongoing search over the past two months, the crew has finally pinpointed the leak using a novel detection method. Simply put, they released tea leaves into the Zvezda module and followed them to the source! According to a statement by Roscosmos, the crew of Expedition 63/64 has patched the hole with some heavy-duty tape they had aboard the station. Talk about DIY repairs!

The repairs began on Thursday, Oct. 15th, the day after Roscosmos announced that the oxygen supply system in the Zvezda module had failed. On that same day, the crew of Expedition 63 – Commander Chris Cassidy and cosmonauts Anatoly Ivanishin and Ivan Vagner – were joined by Expedition 64 Commander Sergey Ryzhikov, and flight engineers Sergey Kud-Sverchkov and Kate Rubins.

Testing for leaks aboard the ISS means suspending all activity within a module and then isolating it from the rest. Alternately, crews can rely on specialized detectors that measure noise created by “turbulent airflow,” – i.e. a leak that’s too quiet for human ears to detect – while the module under inspection is still connected to the rest of the station.

After exhausting these methods, cosmonaut Anatoly Ivanishin opened a tea bag and released a few leaves into the transfer chamber of the Russian Zvezda Service Module. The crew then sealed the chamber off from the rest of the station by closing its hatches and watched on the module’s video cameras as the tea leaves floated around in microgravity.

Slowly, the leaves floated towards a scratch in the wall near the module’s communication equipment, which conclusively showed that this crack was where the station’s air was escaping from. According to the Russian news agency TASS, Ivanishin reported on the procedure during a communications session with Russia’s Flight Control Center on Thurs. Oct. 15th, saying:

“We believe that we have really identified the probable leakage area. We have distributed a teabag [in the Zvezda module] before closing the transfer chamber… We have several photos and videos of the direction of the tea bag’s flight or where it intended to fly and this precisely shows the direction the air is blowing from the possible air leak.”

The crew then patched the leak using polyimide masking tape (aka. Kapton tape), an industrial tape that is extremely resistant to extremes in temperature. Roscosmos posted the news via their Twitter feed on Mon. Oct.19^th, saying:

“The ISS crew sealed the place of the atmospheric leak at the station with temporary means on board. Now the main operational control group, together with the crew of the ISS-63 expedition, is developing an action program for permanent sealing of the leak.”

When the leak was first detected a year ago, NASA and Roscosmos did not consider it to be a major concern. At the time, they were engaged in spacewalks, crew exchanges, and payload deliveries, all of which kept the station and its crew busy and unable to collect enough data about the problem. It was only after the rate of atmospheric loss increased this summer that it became necessary to address it.

In the midst of all this, there were concerns that the usual complement of pressurized air-supply tanks that are regularly sent with resupply missions to compensate for regular air loss would not be enough. Last week, the situation became more concerning when Roscosmos announced that the Zvezda module’s oxygen supply failed, which forced the crew to move to the American segment of the station.

Eventually, the crew narrowed the source to Zvezda’s transfer chamber. But it was not until they performed their little “tea leaf” test that they could be sure exactly where the leak was coming from and could seal it. However, the crew acknowledges that this is a stop-gap measure and a long-term patch will be needed soon. According to TASS, Ivanishin recommended this as well during his report to Russia’s Flight Control Center:

“The air pressure continues falling, although its drop rate has decreased. Perhaps, we should try hard patches our partners have? We can talk with them. This is because the current patch is not so efficient.”

The Zvezda module, which launched in July of 2000, was the first livable part of the station sent to orbit. This module provides the Russian half of the station with oxygen and drinkable water and is equipped with a carbon scrubber that removes CO² from the air. The module also contains the sleeping quarters, dining room, refrigerator-freezer, and bathroom for the Russian section.

Luckily, the US side of the station also has a fully functioning life-support system, which includes oxygen generators, a kitchen, and drinkable water systems. As NASA and Roscosmos stressed many times over, the leak never posed any danger to the crew or its regular operations. Nevertheless, this incident illustrates how the ISS – which has been in continuous operation for 20 years – is showing its age.

Gennady Padalka, the Russian cosmonaut that holds the world record for most days spent in space, addressed this in a statement to the RIA Novosti news agency. “All modules of the Russian segment are exhausted,” he said, adding that the equipment was designed to be used for a maximum of 15 years. Roscosmos is planning on launching new segments for the ISS, but the problem remains.

At present, all major participants in the ISS have all extended their involvement with the mission until 2024 and some expect that the station may remain in operation until 2030. Meanwhile, NAS astronaut Chris Cassidy – the commander of Expedition 63 – formally swapped command with Expedition 64 cosmonaut Sergey Ryzhikov yesterday afternoon.

Ryzhikov officially takes command of operations aboard the ISS today as the crew of Expedition 63 boards the Soyuz MS-16 crew ship to begin the journey home. This event is being broadcast live on NASA TV and will be repeated later today. By 07:33 PM EDT (04:33 PDT), the crew ship will undock from the ISS and conduct its deorbit Burn and landing as of 09:30 AM EDT (06:30 PDT) tomorrow.

Further Reading: Science Alert!, TASS, TASS (2)