To seek out the precise location of the leak in Zvezda so it may be repaired, Cassidy and his crewmates should spend a while floating across the module with a handheld system referred to as an ultrasonic leak detector, which spots frequencies which might be emitted by airflow because it rushes out small holes and cracks. Noise on the station could make it harder to detect these frequencies, and the crew could must run via areas just a few occasions to really discover the supply. One firm needs to enhance on this technique by deploying an automated robot that can “listen” for leaks and identify them in real time, with out the necessity of a human hand. As soon as they’ve discovered the supply of the leak, they may patch it up with a equipment utilizing epoxy resin.

Leaks can even happen in different methods in addition to a lack of oxygen. The ISS has previously dealt with ammonia leaks coming from the station’s cooling loops. Since ammonia is poisonous to people, such leaks require rapid motion, involving prolonged spacewalks to establish holes within the coolant system and restore them. 

The continued challenge goes to point out that even a spacecraft as effectively designed and guarded because the ISS just isn’t invulnerable. And as we see extra international locations and corporations ship people on crewed missions into orbit, such leaks shall be a way more widespread incidence. Not each spacecraft shall be as immune to the issues because the ISS.

There are a few main culprits for the way a leak varieties on a spacecraft. Essentially the most high-profile ISS leak in latest reminiscence was present in August 2018—a 2-millimeter gap on a Russian Soyuz spacecraft docked to the station on the time. That gap seems to have been the results of a drilling error made throughout manufacturing (though Russia’s space agency has been cagey about exactly what caused it). The thriller of that leak was nice fodder for conspiracy theorists, however the truth that the outlet was by accident made by a drill was fortunate. A gap like that’s clear and exact, and never very vulnerable to cracks or growth. 

However when the ISS springs a leak with out a clear trigger, the main suspect is a haphazard collision with a micrometeoroid or small piece of particles (some simply millimeters or much less in measurement). Objects in Earth’s orbit zip round at extraordinarily excessive speeds. The Worldwide Area Station, for instance, has a mean pace of seven.66 kilometers per second, or over 17,000 mph. Some micrometeoroids in area whiz via at over 20,000 mph. At these ultra-high speeds, even tiny objects which might be smaller than a centimeter can completely shred bigger objects, like a bullet from a gun. That form of messy destruction can depart behind cracks or structural harm that propagates via the remainder of the spacecraft hull or pierce via the ammonia coolant system. 

iss detect leaks
A view of the wi-fi ultrasonic leak detector aboard the Worldwide Area Station.

NASA/SHANE KIMBROUGH/JSC

Pressurized spacecraft, normally designed for human habitation, are extra weak to those issues, for the reason that inside stress is placing added stress on the spacecraft hull. “Cracks are extra weak to added stressors,” says Igor Telichev, an engineer on the College of Manitoba in Canada and an professional in spacecraft collisions with particles. “A gap, even a big one, is after all unhealthy, however a crack might begin propagating all through the construction and threaten its whole integrity.” 

Engineers attempt to design spacecraft with shields that may face up to sure collisions from micrometeoroids and small bits of area particles. For the ISS, they used one thing referred to as a Whipple protect (named after its inventor, the late Harvard astronomer Fred Whipple). It’s a skinny outer bumper that’s spaced some distances away from the principle wall of the spacecraft. The bumper doesn’t outright cease incoming micrometeoroids or different small particles, however as an alternative breaks these items up right into a cloud of small particles that fan out over a big space and pose much less of a danger. For the wall, it’s the distinction between going through a single massive bullet and a smattering of birdshot. 

There are a selection of various variants on the Whipple protect—some, for instance, are augmented with Kevlar or ceramic filling between layers. The ISS itself has over 100 totally different Whipple protect configurations, as some areas are extra weak to micrometeoroid collisions than others. 

However as evidenced by the station’s historical past with micrometeoroid impacts, Whipple shields aren’t foolproof. Future crew vehicles and space stations that shall be made for a lot lower than the ISS will doubtless be extra weak to leaks attributable to collisions with small particles and particles. 

When it was first being constructed 20 years in the past, few specialists anticipated what number of extra objects could be coursing via Earth’s orbit. The issue is poised to solely worsen because the area trade expands and people launch more spacecraft than ever into orbit. We are able to construct shielding that accounts for a altering atmosphere, however not even the best models for future debris accumulation can predict all the things. 

In February 2009, the Iridium 33 and Kosmos-2251 satellites collided, creating an enormous swath of particles that started circulating via Earth’s orbit. The most important items have been recognized and tracked, however particles that was lower than 10 centimeters in size—items that also pose a risk to spacecraft hull—was allowed to zip via area undetected. The accident illustrated that unanticipated occasions might drastically exacerbate the issue of defending spacecraft. “Any huge accident might drastically change the scenario and improve the dangers for any variety of different spacecraft in orbit,” says Telichev. “What we develop right this moment won’t be adequate by tomorrow.”

Shielding will help stop leaks from arising, however “this downside is unavoidable,” says Telichev. Meaning it is going to be much more essential to have the ability to isolate and restore leaks as they arrive up.

For Telichev and others, the answer actually comes all the way down to a greater administration of area itself, and decreasing the buildup of particles massive and small. “If the world’s authorities don’t take note of the issue now,” he says, “it’s not going to go away by itself.”

Cassidy and his crewmates have been nonetheless in search of the leak as of Wednesday morning. A Northrop Grumman Cygnus resupply mission is scheduled to launch Thursday evening, adopted by a SpaceX Crew Dragon mission on October 14 to convey one other two cosmonauts and one astronaut to the ISS. Between unpacking the brand new provides and scientific experiments, and welcoming the brand new crew, there gained’t be a complete lot of time to search out the leak over the subsequent few weeks, so the stress is, figuratively, on.