Officials from NASA and Russia’s space agency don’t see eye to eye on the causes and risks of small but persistent air leaks on the International Space Station.
That was the word from the new chair of NASA’s International Space Station Advisory Committee last week.
Air has been leaking from the transfer tunnel since September 2019.
This prompted managers to elevate the transfer tunnel leak to the highest level of risk in the space station program’s risk management system.
“The station is not young,” said Michael Barratt, a NASA astronaut who returned from the space station last month.
There is disagreement between Russian space agency officials and NASA officials regarding the causes and dangers of minor but recurring air leaks on the ISS.
NASA’s International Space Station Advisory Committee’s new chair said as much last week. One of the earliest components of the complex, the transfer tunnel of the Russian Zvezda service module of the space station, is where the air leaks are located.
According to Bob Cabana, a retired NASA astronaut who assumed leadership of the advisory committee earlier this year, US and Russian officials “don’t have a common understanding of what the likely root cause is, or the severity of the consequences of these leaks.”. Tom Stafford, a former Apollo astronaut, chaired the committee until his death in March; Cabana took over as chairman.
PrK, the Russian abbreviation for the transfer tunnel, links the Zvezda module to a docking port where Progress resupply spacecraft and Soyuz crew dock with the station.
Since September 2019, air has been seeping out of the transfer tunnel. The leak rate has been momentarily decreased and the cracks have been patched by Russian cosmonauts on multiple occasions. The leak rate increased to 2 to 4 pounds per day in February and then to 3 to 7 pounds per day in April.
This led managers to raise the transfer tunnel leak to the highest risk level in the risk management system for the space station program. This 5×5 “risk matrix” categorizes risks according to their odds and potential outcomes. The leaks are now categorized as a “5” in terms of both high likelihood and high consequence, according to a June Ars report.
The most recent set of repairs reduced the leak rate by a third, but NASA reported in September that the issue was still present.
A problem in engineering.
According to Cabana, “the Russian position is that high cyclic fatigue caused by micro-vibrations is the most probable cause of the PrK cracks,” on November 13. According to NASA, there are several possible causes for the PrK cracks, including residual stress, pressure and mechanical stress, material characteristics, and environmental exposures. “.”.
The International Space Station is getting older. Next year will commemorate Zvezda and the PrK’s 25 years in orbit, having launched in July 2000. Roscosmos, the Russian space agency, has only committed to running the space station through 2028, whereas NASA wants to keep it running until at least 2030.
Roscosmos has provided NASA with investigation reports, welds, and sample metals to help with the crack and leak analysis. NASA’s ISS Vehicle Office at Johnson Space Center in Houston stated in a September report that the leaks are “not an immediate risk to the structural integrity of the station.”. “.”.
This is because in the event that the PrK’s structural integrity fails, managers have put mitigations in place to safeguard the entire station.
While not in need of access to the Progress cargo freighter docked at the opposite end of the transfer tunnel, crew members on board the space station are keeping the hatch leading to the PrK closed. In order to load trash into the ship for disposal or unpack supplies from the Progress, Russian cosmonauts must open the hatch.
However, Roscosmos and NASA cannot agree on when the rate of leaks would become unsustainable. In order to seal off the PrK and protect the rest of the complex from a major failure, the space station crew will have to permanently close the hatch at that point.
Michael Barratt, a NASA astronaut who returned from the space station last month, stated, “The station is not young.”. It’s been up there for a long time, so you anticipate some wear and tear, which is what we’re witnessing. “.
Cabana, who served as NASA’s top civil servant until his retirement in 2023, stated, “The Russians believe that continued operations are safe, but they can’t prove to our satisfaction that they are.”. Additionally, the US thinks it’s unsafe, but we are unable to satisfy Russia with our proof.
Cabana stated, “The Russian team does not think catastrophic disintegration of the PrK is realistic, even though it is still searching for and sealing the leaks.”. Additionally, NASA has voiced worries about the PrK’s structural soundness and the potential for a disastrous malfunction. “,”.
One of the space station’s four Russian docking ports would be inoperable if the PrK hatch were permanently closed.
According to Cabana, NASA has enlisted a group of impartial specialists to evaluate the fractures and leaks and assist in identifying the underlying cause. As an engineering problem, this should be something that competent engineers can agree upon. “.”.
Barratt stated that when cosmonauts are working in the PrK, space station crews are also closing the hatch that separates the US and Russian portions of the station as a precaution.
Barratt stated, “The way it’s affected us, mostly, is that they’ve taken the time to inspect and try to repair when they can, as well as go in and open that to unload a cargo vehicle that’s docked to it.”. “For those times, we’ve adopted a very cautious stance in trying to mend the rift between the Russian and American sides.
Although it’s uncomfortable, it’s the best compromise reached by all the knowledgeable individuals on both sides, and as a crew, we’ve learned to live with it. “..”.
