Getting the aging International Space Station through another six years won’t be easy.
A recent report out last month from NASA’s Office of the Inspector General highlighted some of the big challenges to keeping the ISS flying safely, from replacing aging parts and maintaining supply lines 250 miles above the planet to space debris and a worryingly persistent leak in the Russian segment of the station.
But despite its old age, the venerable ISS still has an important role to play. For one, it’s still a cornerstone of NASA’s plans for the Moon and Mars, and it still plays a crucial role in research from Earth science and medicine to astronomy and physics. This leaves NASA and other space agencies that keep the ISS in a predicament: How will they keep this deteriorating vehicle standing? Right now, no one is completely sure.
Logistics, Location, and Leaks
An aging space station has some of the same problems you'd get with an aging car — just with higher stakes. Parts start to wear out more often, but the older the vehicle gets, the harder (and more expensive) it is to find replacements. Now pretend your aging car is 250 miles above the planet's surface, and only a handful of vehicles in the world can actually get there to deliver replacement parts.
“Upgrades of key replaceable parts may be more difficult to acquire as suppliers decrease or cease production,” the OIG report read. “Further heightening this risk is the current reliance on a single launch provider [SpaceX] for cargo and crew.” Boeing’s Starliner spacecraft, whose crew remains stranded aboard ISS after June’s fiasco of a test flight, was meant to help solve precisely that problem.
But the elephant in the room is a leak in the Russian segment of the station.
Why is the ISS Leaking?
About 1.2 pounds of air escape into space every day through cracks in the Service Module Transfer Tunnel, which connects Russia’s Zvezda module to a docking port for Russian Progress uncrewed cargo ships. At its worst, in April 2024, the tunnel was leaking 3.7 pounds of air every day, but repair work earlier this year helped reduce the loss.
To put the leak in perspective, the ISS has about the same volume of pressurized, air-filled space as a Boeing 747. Astronauts aren’t facing the space equivalent of a jetliner’s door plug falling off mid-flight, but when your life depends on keeping air in and the vacuum of space out, any leak is cause for concern.
“Not an impact right now on the crew safety or vehicle operations, but something for everybody to be aware of,” said NASA’s ISS program manager Joel Montalbano in a February 2024 statement, when the leak was at 2.4 pounds a day.
The severity of the leak has fluctuated since its discovery in September 2019, as some small cracks get repaired and others open. Overall, it’s a worsening problem, one that the OIG report calls “a top safety risk.”
Repairs — mostly applying sealant to cracks as they’re found — have kept the leak at “manageable” levels over the last 5 years, but cosmonauts also try to keep the Zvezda module’s hatch closed as much as possible to limit how much air gets lost from the rest of the station.
“Zvezda’s hatch remains closed to the extent possible, including around Progress spacecraft cargo operations,” a NASA spokesperson told Inverse.
High Stakes in Low Earth Orbit
If the leak becomes “untenable,” as the OIG report puts it, the transfer tunnel may have to be closed off altogether, like the sealed-off wing of a slowly decaying mansion in a Gothic horror novel — but in space.
That could be a bigger problem for the ISS than it looks at first glance.
The transfer tunnel contains one of the Russian module’s 4 docking ports for cargo ships, so losing it could cause traffic problems and delays in keeping the station supplied. And cargo ships docked at that port often fire their own engines to boost the ISS back into its proper orbit; at 250 miles above Earth’s surface, there are just enough air molecules floating around to gradually slow the station, dragging it downward, unless it gets a periodic boost. Without the occasional nudge from a visiting Progress ship, the ISS would have to use its own thrusters for the job. This would require burning more propellant and putting more strain on aging systems.
Meanwhile, NASA and Roscosmos don’t even agree on what counts as an “untenable” leak rate. And the root cause of the leak remains elusive; cosmonauts have found and sealed several cracks over the years, but the leaks keep happening.
“Cosmonauts aboard the Space Station have performed inspections of the module’s interior surfaces with an instrument that can detect even the most minor surface blemishes,” NASA’s spokesperson said. “There are several areas of interest identified subject to future Roscosmos inspections. Roscosmos has not confirmed these areas of interest to be cracks. They could be benign imperfections typically seen on a surface, like a small scratch.” According to the OIG report, the main suspect right now is a series of welds, both inside and outside the tunnel.
The “International” Part is Key
The relationship between NASA and Roscosmos has been strained in recent years. Russia hasn’t yet committed to keep its part of the ISS running through 2030, which includes things like cost-sharing, maintenance, and inspecting its modules and certifying that they’re structurally sound. Nor has it committed to NASA’s plan to to de-orbit the ISS by pulling it down into Earth’s atmosphere with a spacecraft. This plan requires using Russian propulsion to keep the space station at cruising altitude and correctly oriented until it’s time to bring it down.
“Without commitment from Russia to the current deorbit plan, the ability to conduct a controlled deorbit is uncertain,” according to the OIG report. “NASA anticipated that Roscosmos would commit to the Agency’s ISS deorbit plan — which requires a continued partnership through 2030 — in the summer of 2023. However, as of June 2024, negotiations continue, and no agreement has been finalized.”
But, like the transfer tunnel, the relationship between the two space agencies hasn’t quite become untenable so far.
“NASA is working with Roscosmos,” said the NASA spokesperson in response to questions about the leak. “The station partners are sharing information about the status of the leak, onboard investigation, and mitigation steps.”
Are We Really Ready to Lose the ISS?
If everything goes according to plan, the International Space Station will go out in a blaze of glory sometime in 2030 or 2031. NASA announced in July that it had awarded a contract to SpaceX to design and build a spacecraft to pull the station down into Earth’s atmosphere — allowing NASA to control when and where the 450-ton (if you were weighing it on Earth) station enters the atmosphere, and thus where most of the debris from its breakup will land (in a remote area of the Pacific Ocean known as Point Nemo or the Spacecraft Cemetery).
But that’s not guaranteed to happen.
Before the ISS makes it big curtain call in 2030, NASA hopes to replace it with commercially-run space stations, which would host a mix of space agency researchers and private visitors (picture a combination of space tourism and corporate R&D, most likely).
“NASA’s goal is to be one of many customers in a robust commercial marketplace in low Earth orbit where in-orbit destinations and cargo and crew transportation are available as services to the agency,” NASA’s spokesperson said. “Transitioning operations and services in low Earth orbit to private industry allows NASA more time to focus on deep space human missions to the Moon under the Artemis campaign, and ultimately, Mars.”
But so far, those longed-for commercial stations don't exist yet, and in its recent report, NASA’s OIG is skeptical about whether they’ll make it to orbit in time to replace the ISS. If not, we'll have a tough choice to make: either go without a place in LEO — which would mean giving up on much of the research that will give humans a long-term foothold on the Moon, not to mention developing new medicines for use here on Earth — or find a way to keep the aging station going a little longer.
