The International Space Station has been leaking for five years

In the hostile conditions beyond Earth, a spaceship is all that stands between an astronaut and certain death. So having seemingly unsolvable leaks on the International Space Station (ISS) for years sounds like a nightmare scenario. It's also a reality that a recent agency report calls the “biggest security risk.” Amid months of headlines about astronauts stranded by Boeing's Starliner vehicle and NASA's announcement of a deal with Elon Musk's SpaceX to destroy the ISS early next decade, ongoing concerns about the leaks are another reminder that The importance of supporting a long-term population in space is a challenge that is literally out of this world.

At the same time, the station's leaks are trivial — perhaps shocking to those of us who are neither engineers nor astronauts. “When you're on the space station, it's like living here,” says Sandra Magnus, an engineer at the Georgia Institute of Technology and former NASA astronaut who previously served on NASA's Aerospace Safety Advisory Panel, an independent panel that governs the Security monitors concerns. “You don't run around in your everyday life wondering if you're going to get hit by a car while crossing the street, do you? It’s your life – you just live your life.”

The disturbing truth is that the ISS loses some air every day – and always has. “All spacecraft leak,” says David Klaus, a professor of aerospace engineering at the University of Colorado Boulder. The space station is simply the most recognizable spacecraft in existence, and it's leaking more now than it used to.

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It's actually leaking more, but still not as much, says Michael Kezirian, an associate professor of aerospace engineering at the University of Southern California. The current leak is “bigger than one pinhole, maybe two pinholes,” he says. “You're talking about something relatively small.” The worst publicly reported leak rate was in April, when the station lost 3.7 pounds of atmosphere per day. (For comparison, all the air over a given square inch of Earth's surface at sea level, extending to the end of the atmosphere, weighs, on average, just under 15 pounds.)

To experts, it's not even particularly surprising that NASA and the international partners that operate the space station have had so much trouble tracking down and fixing the leaks. “Leaks are difficult to fix,” says Magnus. “The station is huge; There is a large amount of air. “So it's difficult to isolate a tiny leak or something else that doesn't have that many leaks.” (Much of the station's hull is also difficult to access from the inside due to the sheer volume of equipment, cargo and other material Things clutter up its corridors.)

Don’t panic – not yet

The problematic leaks, first discovered in September 2019, were traced to a tunnel in Russia's Zvezda service module, which launched in July 2000. The tunnel connects a docking port to the main body of the module – and the rest of the space station module. Magnus describes the tunnel as “the back porch”, used primarily to store garbage to be burned in Earth's atmosphere.

Astronauts over the years have had some luck pinpointing exact locations where the station is leaking air and have even attempted to repair the tunnel. In theory, leaks in spacecraft can easily be sealed from the inside. “All you have to do is press something with some kind of adhesive against the leak and it will press itself against the leak,” says Klaus. “The pressure in the spacecraft helps keep the seal against the leak.” However, these patching efforts have only reduced the spread of the leaks rather than eliminating them completely.

While astronauts and ground control continue troubleshooting, NASA and its Russian counterpart, Roscosmos, have decided to keep the leaky tunnel's hatch closed if possible. It's a simple but sensible solution, says Magnus, given the relatively minor importance of the back porch. As long as leaks remain constant, Klaus says the only real problem is that astronauts may require more frequent or larger quantities of air, one of the many so-called consumables such as food and water that are supplied by cargo vehicles at the station.

If the leaks worsen, the stopgap strategy could become a permanent solution without serious consequences in the long term, all three experts say. Losing access to the port at the other end of the tunnel would be inconvenient and would require closer coordination of crew and cargo vehicles visiting the orbiting laboratory and the material they deliver. “They need to sharpen their pencils in the logistics industry and figure out how to compensate for this,” Magnus says of this scenario. “Will it be a disaster? No. Will it be a little more challenging? Perhaps.”

Even this approach comes with its own complications: According to the September report, NASA and Roscosmos disagree about the threshold at which leaks become so severe that the hatch needs to be permanently closed.

Still, the leaks themselves, while far from ideal, are essentially under control. “Nobody should panic,” says Magnus. “It's a serious issue and they're taking it seriously, that's really the bottom line.”

wear and tear

But the leaks are also a painful reminder of how long the ISS has already spent in orbit. The oldest segments were introduced in 1998; Since then, they have endured a variety of stressors. Spaceships arrive and take off, rockets propel the ever-sinking laboratory higher above the earth and materials decompose due to the effects of cosmic radiation. And the sun's heat comes and goes 16 times each day as the station floats over the night and day sides of the Earth, causing its components to expand and shrink each time.

Sooner or later – hopefully later – the toll of all this mechanical stress will manifest itself in something more serious than pinprick leaks. “We know that the space station can’t stay up there forever,” says Kezirian. “With an old house, it's a little easier to paint and replace broken components.” Home repairs on a space outpost are both more expensive and more involved, and at some point entropy will win.

NASA hopes this won't happen this decade and aims to keep the space station operational until 2030. (Russia has so far only committed to building the orbiting lab by 2028.) But the challenges with leaks add urgency to a concern that the Aerospace Safety Advisory says the panel has expressed for years that the orbiting lab will fail, before it can be safely destroyed – and will plunge uncontrollably through Earth's atmosphere, its debris potentially causing serious damage to people and buildings. Earlier this year, NASA commissioned SpaceX to develop a vehicle that would safely deorbit the space station in 2031, with a planned launch in 2029. That's a very tight timeline for a program of this magnitude, so concern remains consist.

A second ticking clock looms over the agency: No matter what state the space station is in as it approaches its fiery demise, it will leave the U.S. without viable long-term habitats in orbit. NASA officials have for years promoted the idea of ​​companies taking over low-Earth orbit by launching and maintaining space stations to continue the ISS's 24-year streak of continuous human occupation.

Leave orbit again?

In 2020, the agency contracted with Texas-based Axiom Space to build the first habitable, commercially built module on the space station. The company hopes to launch it in 2026 and then undock and fly freely when the space station retires. In 2021, NASA also awarded funding to companies including Washington state-based Blue Origin (owned by Amazon's Jeff Bezos) and Texas-based Nanoracks to develop additional commercial targets in space. NASA said the Axiom module is under construction and that components of the Blue Origin station have been tested, but progress remains slow. Company representatives from each station contacted for this article did not provide further information about their current status Scientific American. Meanwhile, Axiom is reportedly in serious financial trouble.

These proposed commercial stations could potentially learn from the ISS's leak problems, says Klaus. “Once you identify this as a potential problem, you can be smarter about future designs,” he says. “If you're smart, you don't experience the same failures twice. It happens once; You fix it and move on.”

But there are growing fears that these stations will no longer be operational if the ISS has to be decommissioned or becomes uninhabitable, leaving the US only able to make short trips into Earth's orbit.

For NASA, the prospect bears an uneasy resemblance to the retirement of the space shuttle fleet in 2011 without an active replacement. For nearly a decade, the agency bought its astronaut seats on Russian spacecraft to get to the ISS — an expensive strategy in a financial sense, but also in terms of lost knowledge and expertise in the U.S. space industry.

“You really don’t want something like that to happen again,” Magnus says. “If we want to be a nation that explores space, then we must do so in a smart, cost-effective and maximal way. [An approach in] The interaction is simply not optimal and wasteful.”