The Orion toilet on Artemis 2 remains operational, but engineers are troubleshooting a venting issue that has caused urine to back up and produced an unexplained burning smell. Heaters and reorienting the spacecraft toward the Sun did not clear a suspected ice blockage. Mission teams now suspect a chemical reaction involving anti-biofilm additives may be creating debris that clogs a filter. A definitive diagnosis will await on-ground inspection after Orion's scheduled splashdown off San Diego on April 10.
Artemis 2's Space Toilet Works — But a Mysterious Venting Issue Persists
The toilet on the Artemis 2 mission's Orion spacecraft is getting a lot of attention these days. | Credit: NASA/Canadian Space Agency
Sorry, but we need to talk about Artemis 2's space toilet again — and this time the update is more reassuring, even if a problem remains unresolved.
What happened: The compact toilet aboard NASA's Orion capsule has attracted attention since the Artemis 2 mission launched on April 1, both because it is the first toilet to fly beyond low Earth orbit and because crew members reported urine backing up and an unexplained burning odor.
Toilet Is Operational
On April 7, the day after Artemis 2's historic lunar flyby, Flight Director Rick Henfling confirmed the good news: "The toilet remains operational." The system is a scaled-down version of the International Space Station's sanitation system and is intended to handle urine and wastewater in deep-space conditions.
Venting Issue and Odor
The primary issue has been difficulty evacuating stored urine from Orion's waste tank. Henfling explained that the external vent is providing "a lot less" flow than expected, forcing the crew and mission team to rely on alternate methods rather than the toilet's normal venting process. Crew members also reported an odd burning smell coming from the toilet; Mission Control has not judged the odor to be an immediate safety concern.
Artemis 2 astronaut Christina Koch works with a test version of the Orion space toilet on Earth before launch. | Credit: NASA
What Engineers Tried
Engineers initially suspected that ice might be blocking the external vent nozzle. Teams engaged heaters and rotated Orion to face the Sun to try to "bake away" any ice, but those steps did not resolve the problem.
Current Leading Theory
Henfling described the current working hypothesis as chemical in nature: additives used in the wastewater to inhibit biofilm growth may be reacting and producing debris that is clogging a filter in the venting system. That theory remains unconfirmed until technicians can inspect the hardware directly.
"As soon as we get this [spacecraft] down on the ground, we'll be able to get inside, and we will get to the root of that," said Lori Glaze, acting associate administrator for NASA's Exploration Systems Development Mission Directorate.
Orion and its four-person crew — NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, alongside Canadian Space Agency astronaut Jeremy Hansen — are scheduled to splash down off the coast of San Diego on Friday evening, April 10. After recovery, teams will open and examine the system to identify the root cause and determine any needed design or procedural changes.
Why it matters: Artemis 2 marks the first crewed flight beyond low Earth orbit since Apollo 17 in 1972, and resolving this venting issue will be important for future long-duration deep-space missions where reliable wastewater handling is essential for crew health and vehicle systems.
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