posted 08-20-2020 01:07 PM               

Crew spending weekend in station's Russian segment to investigate air leak

The three Expedition 63 crew members living aboard the International Space Station will spend the weekend inside the orbiting lab's Russian segment. Commander Chris Cassidy and his crewmates Ivan Vagner and Anatoly Ivanishin will stay in the Zvezda service module from Friday night (Aug. 21) into Monday morning.

The station's atmosphere is maintained at pressure comfortable for the crew members, and a tiny bit of that air leaks over time, requiring routine repressurization from nitrogen tanks delivered on cargo resupply missions. In September 2019, NASA and its international partners first saw indications of a slight increase above the standard cabin air leak rate.

Because of routine station operations like spacewalks and spacecraft arrivals and departures, it took time to gather enough data to characterize those measurements. That rate has slightly increased, so the teams are working a plan to isolate, identify, and potentially repair the source. The leak is still within segment specifications and presents no immediate danger to the crew or the space station.

All the space station hatches will be closed this weekend so mission controllers can carefully monitor the air pressure in each module. The test presents no safety concern for the crew. The test should determine which module is experiencing a higher-than-normal leak rate. The U.S. and Russian specialists expect preliminary results should be available for review by the end of next week.

The three station residents will have plenty of room in Zvezda this weekend. The module provides the living quarters that enabled permanent human habitation to begin nearly 20 years ago when the Expedition 1 crew arrived at the station Nov. 2, 2000. Cassidy, Vagner, and Ivanishin also will have access to the Poisk mini-research module and their Soyuz MS-16 crew ship for the duration of their stay.

posted 08-22-2020 01:36 PM            

All three in Zvezda module.

Ivan Vagner in Progress MS-15 as wash zone.

Chris Cassidy's sleeping place in Poisk module.

posted 08-24-2020 05:18 PM               

Crew spends another day in Russian segment

The three Expedition 63 crew members will spend another day inside the Russian segment of the International Space Station. Mission controllers are continuing their leak detection work today to collect more data.

All of the orbiting lab's hatches will remain closed until Tuesday morning to give ground specialists additional time to collect data and monitor pressure readings in each module.

posted 08-25-2020 12:06 PM               

Station crew re-enters U.S operating segments

The Expedition 63 crew ended its stay isolated in the Russian segment of the International Space Station this morning (Aug. 25) after an extended leak test.

Commander Chris Cassidy started the day reopening the hatches to the U.S. segment to begin resuming normal station operations. He reactivated U.S. life support equipment and restowed U.S. gear used during the crew's weekend stay in the Zvezda service module.

Mission control will study the test data this week in an effort to determine the source of a cabin air leak detected in September of 2019. The rate is still well within segment specifications and presents no danger to the crew or the space station.

Roscosmos Flight Engineer Anatoly Ivanishin spent the morning reconfiguring the Russian segment of the orbiting lab. The veteran station cosmonaut checked pressure valves and communications gear while opening hatches to various Russian modules.

Flight Engineer Ivan Vagner, on his first station mission, started the day resetting Russian life support equipment and sampling the air in Zvezda for analysis.

posted 09-24-2020 07:23 PM               

Both Moscow and Houston Mission Control Centers have been tracking a tiny air leak for several months. A few weeks ago our crew isolated in the Russian segment of space station and closed as many hatches as possible in order to identify the location of the leak.

Strangely the data did not point us to any particular location. Yesterday and today, Anatoly [Ivanishin] and I have been checking all of the window seals (not Navy SEALs) for any indication of a leak using an ultrasonic leak detector.

So far no luck finding the source, but it looks like we will try again with the module isolation this weekend. No harm or risk to us as the crew, but it is important to find the leak we are not wasting valuable air.

posted 09-29-2020 10:03 AM               

After a thorough analysis and search of the air leak at the International Space Station, the leak was located in the Zvezda Service Module containing scientific equipment.

The leak is localized in the working compartment of the service module.

Currently the search is underway to precisely locate the leak. With that, the general atmosphere pressure decrease rates remain at 1 mm per 8 hours. The situation poses no danger to the crew's life and health and doesn't hinder the station continued crewed operation.

posted 09-29-2020 10:07 AM               

Crew Continues Troubleshooting as Tests Isolate Small Leak

Late Monday night (Sept. 28), the Expedition 63 crew was awakened by flight controllers to continue troubleshooting a small leak on the International Space Station that appeared to grow in size. Ground analysis of the modules tested overnight have isolated the leak location to the main work area of the Zvezda Service Module. Additional work is underway to precisely locate the source of the leak.

The leak, which has been investigated for several weeks, poses no immediate danger to the crew at the current leak rate and only a slight deviation to the crew's schedule.

NASA astronaut and station commander Chris Cassidy and Roscosmos cosmonauts Anatoly Ivanishin and Ivan Vagner were instructed to move into the Russian segment to collect data at various locations in the Russian modules. The size of the leak identified overnight has since been attributed to a temporary temperature change aboard the station with the overall rate of leak remaining unchanged.

Previous leak checks were conducted in the modules in the U.S. segment of the station.

One by one, the crew closed hatches between Zvezda's aft and forward sections and Zvezda's passageways to the Pirs Docking Compartment and the Poisk module while using an ultrasound leak detector to collect data. Throughout the night, pressure measurements were taken by U.S. and Russian specialists to try to isolate the source of the leak. At the completion of the overnight checks, the crew opened hatches once again between the U.S. and Russian segments and resumed regular activities.

posted 10-02-2020 09:50 AM               

One of the cameras will look at the vacuum meter to understand how quickly the pressure in the compartment is dropping, and the other will watch the movement of indicators, which, according to experts, will indicate where the air leak is.

The idea of ​​the specialists is that due to the leak there will be a micro flow of air, due to which the fixed strips will deviate in the direction of the leak, and the freely floating strips will be grouped near the leak. In this case, video from cameras will be transmitted in real time to the crew and to the Earth.

posted 10-19-2020 11:43 AM               

We believe that we have really identified the probable leakage area. We have distributed a tea bag 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.

On Monday (Oct. 19), Roscosmos said a permanent seal is being worked.

ISS crew sealed the airleak using temporary means available at the station.

Currently, Chief Operating Control Group together with the space station crew is working out a program of operations to permanently seal the leak location.

posted 03-02-2021 06:11 AM               

On March 1, the cosmonauts will fill the crack with the sealant, then lay polyurethane foam and patch up the fracture with the tape, the Flight Control Center specified.

"The work [must be carried out] with the use of individual protection gear," the specialist stressed. Specifically, the cosmonauts would need to use alcohol wipes and respirators and carry out work on command from Earth instead of using a timing diagram, he said.

As follows from the talks, then a hole will be drilled at one of the fracture’s ends, which will be filled with cold welding and sealed with a fluoroplastic film on top. The same procedure will be done with other holes. After that, the surface will be sanded and wiped with alcohol wipes and covered with a sealant. Overall, the cosmonauts will put three layers of the sealant.

posted 03-03-2021 08:44 AM            

The ISS isn't an airplane. It's not like it’s going through frequent full pressurization cycles.

posted 03-03-2021 12:49 PM               

"They are studying the possibility of the seal failure due to metal fatigue or the impact of a micrometeorite, which could pierce the assembly compartment [under which the intermediate chamber is located]," the source said.

According to the source, Russian cosmonauts will examine the Zvezda module's surface during a spacewalk in the summer to detect the micrometeorite's impact that could cause an air leak.

posted 03-09-2021 08:30 AM               

Microscopic and eddy-current flaw testing of the affected area showed that one of the cracks is 22 mm long and only about 100 microns wide. Given the minor sizes, it was impossible to discover the cracks using onboard equipment only.

The results of the thorough study were sent back to Earth to develop the repair method.

Currently, works are underway to localize and hermetically seal the cracks; the works are to be conducted for the next few days.

To seal the cracks, two types of sealing paste and sealing material are to be used. The edges of the cracks will be drilled with a 3-mm drill to limit possible crack growth. The holes will be sealed straight away to minimize the pressure drop. After that, several more layers of seal paste will be applied with a reinforced patch, which will be covered with another layer of sealing paste.

The metal borings will be sent back to Earth in addition to the instrument data and photos collected earlier for further analysis.

After completing the works, a leak check of the Transfer Chamber will be performed.

All the Russian crew's operations are being agreed with NASA specialists stage-by-stage on an instruction from state corporation Roscosmos chief Dmitry Rogozin.

Last week, cosmonaut Ryzhikov applied three layers of a sealant and placed a patch on the first crack in the Zvezda module. On March 6, he applied another layer of the sealant from the end of the installed patch.

The cosmonauts will carry out the work to seal the second fracture this week. On March 8, the cosmonauts elaborated a detailed plan under the direction of specialists from the ISS Russian Segment's main operational control group for further repair and recovery work. The Russian crewmembers also prepared the necessary equipment for treating the module's surface, applying the sealant and placing a patch.

posted 03-11-2021 08:01 AM               

The International Space Station crew has completed the repair works of the Zvezda module hull. In the coming days Roscosmos cosmonauts Sergey Ryzhikov and Sergey Kud-Sverchkov will close the Zvezda module hatches to perform pressure level checks.

posted 06-14-2025 01:52 PM               

Cosmonauts aboard the space station recently performed inspections of the Zvezda service module's transfer tunnel, sealed some additional areas of interest, and measured the current leak rate.

Pressure in the transfer tunnel is now stable. Previously, pressure in this area would have dropped. This could indicate the small leaks have been sealed. Teams are also considering the stable pressure could be the result of a small amount of air flowing into the transfer tunnel across the hatch seal from the main part of space station. By changing pressure in the transfer tunnel and monitoring over time, teams are evaluating the condition of the transfer tunnel and the hatch seal between the space station and the back of Zvezda.

posted 06-19-2025 08:59 AM               

The concern is that some of these metal structures on board the station could fail quickly and catastrophically. Accordingly, in its previous assessments, NASA has classified the structural cracking issue on the space station as the highest level of concern on its 5v5 risk matrix to gauge the likelihood and severity of risks to the space station.