Issues with a toilet on board SpaceX’s Crew Dragon capsule will potentially leave four astronauts without a bathroom throughout their hour-long journey back to Earth from the International Space Station this month.

“The crew will have to rely on undergarments,” Steve Stich, NASA’s Commercial Crew Program manager, told reporters Friday night.

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Last month, while inspecting a different Crew Dragon capsule, SpaceX noticed an issue with its toilet. A tube designed to funnel pee into a storage tank had become unglued, leaving a gushing mess beneath the capsule’s floor, according to the company. It’s a problem that has so far impacted all three of the company’s spacecraft.

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NASA did not specify how long the four astronauts — NASA’s Shane Kimbrough and Megan McArthur, French astronaut Thomas Pesquet, and Japanese astronaut Akihiko Hoshide — will be stuck on board their Crew Dragon capsule with an inoperable toilet. Only two Crew Dragon spacecraft have returned from the ISS with people on board so far, and the first took 19 hours while the second took only six.

The journey’s timing will be determined by a number of factors, including how orbital dynamics and weather affect it, but “we are working to try to always minimize that time from undock to landing and so that’s what we’ll do with this flight,” Stich added

In September, a fault with Crew Dragon’s toilet was discovered for the first time during SpaceX’s Inspiration4 mission, which took four people on the first all-tourism mission to space, where they stayed three days. 

Last month, Jared Isaacman, the commander and financier of the Inspiration4 mission, told CNN Business that during the trip, an alarm went off, warning the crew about a problem with the toilet’s fan. He and his fellow passengers had to work with SpaceX controllers on the ground to troubleshoot, he said.

“There’s a storage tank where the urine goes to be stored [and] there’s a tube that came disconnected or came unglued,” said William Gerstenmaier, SpaceX’s head of mission assurance. “That allowed urine essentially to not go into the storage tank, but essentially go into the fan system.”

The incident demonstrates how spacecraft that have undergone all essential test flights, been inspected and certified, and even completed full missions can still have design flaws.

“In this particular case, the Inspiration4 crew did not notice any excreta floating around the cabin because the leakage was still relegated to sealed-off areas underneath the floor,” Gerstenmaier said.

On the Inspiration4 spacecraft, dubbed Resilience, SpaceX is working to clean up and correct the problem. The fix will be built into the brand new Crew Dragon spacecraft, named Endurance, which is scheduled to launch four more astronauts to the ISS on Wednesday.