Artemis II Crew Reports Toilet Failure and Burning Smell Aboard Spacecraft

On Day 1 of humanity's return to deep space, the Artemis II crew ran into an ancient problem: the bathroom stopped working. The Universal Waste Management System — a 3D-printed titanium toilet built by Collins Aerospace under a roughly $30 million NASA contract — malfunctioned within an hour of launch, forcing four astronauts to resort to backup urine bags while hurtling toward the Moon at thousands of miles per hour [1][2]. Two days later, the crew reported a burning smell emanating from the same system, an odor that ground teams have still not definitively explained [3].

The incidents, while not mission-threatening, raise pointed questions about NASA's ability to solve what is arguably the most persistent engineering problem in human spaceflight — and whether the agency's own testing protocols caught warning signs that were already visible years before launch.

What Happened: A Two-Act Malfunction

Act One: The Fan Jam (Day 1, April 1)

Approximately one hour after the Space Launch System rocket delivered the Orion capsule to orbit, a controller malfunction caused the Dual Fan Separator (DFS) — the component responsible for generating suction in microgravity — to jam [4]. Without suction, the toilet cannot collect or route liquid waste. Mission Control worked with mission specialist Christina Koch to troubleshoot the unit, a process that took roughly six hours [4]. During that window, all four crew members — commander Reid Wiseman, pilot Victor Glover, Koch, and Canadian Space Agency astronaut Jeremy Hansen — used Collapsible Contingency Urinals (CCUs), essentially high-tech plastic bags that can vent waste water overboard independently of the main system [5][6].

The toilet was restored to partial function by end of Day 1.

Act Two: Frozen Urine and a Burning Smell (Days 3–4, April 3–4)

On Day 3, at roughly 200,000 miles from Earth, the crew reported a second failure: urine had frozen in the vent line that ejects liquid waste into space [7]. This was a thermal problem specific to deep space — the vent line, designed and tested in low Earth orbit conditions aboard the International Space Station, was exposed to temperature extremes that simply do not exist at ISS altitude [4]. Mission Control's solution was to rotate the entire Orion capsule to put the frozen line in direct sunlight, thawing the blockage [7][8].

During this period, Koch reported a "burning heater smell" that appeared to originate from the toilet area [3]. Ground teams checked all thermal and electrical systems and used an onboard atmospheric gas analyzer to test cabin air composition. Neither check revealed an anomaly [9]. Controllers initially suspected orange insulation material around the hygiene bay door, but this was never confirmed [3]. The source of the smell, as NASA later acknowledged, "was never identified" [10].

The toilet was restricted to solid-waste use only for several hours before full function was restored [4].

The UWMS: A Troubled Testing History

The Universal Waste Management System was not an untested prototype. Collins Aerospace won the initial contract in 2015 to design a toilet that could serve both the ISS and the Orion deep-space capsule [11][12]. The selling points were significant: 65% smaller and 40% lighter than the existing ISS toilet, with a 3D-printed titanium construction [12].

But the ISS demonstration program — intended as an operational dress rehearsal — never achieved its full objectives [4]:

• October 2020: The unit shipped to the ISS. Initial checkout revealed odor issues and a "locked rotor" fault in the Dual Fan Separator — the same component that failed on Artemis II's Day 1 [4].
• 2023: A second test attempt stopped after three days when a dose pump failed [4].
• 2024: Another DFS startup problem, traced to controller circuit issues [4].
• Odor Bacteria Filter: Failed to meet capacity requirements during testing, achieving "odor breakthrough" at 50–75% of its rated lifespan [4].

The Orion-specific UWMS unit was delivered in December 2019 and installed in the Artemis II vehicle in March 2021 [11]. It sat inside the capsule, untested in its flight configuration, for five years before launch [4].

Source: NASA TechPort, CNN, KeepTrack.space

Data as of Apr 7, 2026CSV

NASA Associate Administrator Amit Kshatriya framed the malfunctions as expected: "Artemis II is a test flight, and the test has just begun" [4]. Project Manager Melissa McKinley indicated the mission data would "drive waste management design for the entire lunar and Mars campaign" [4] — an implicit acknowledgment that the current design requires modification before Artemis III.

A Design Built on Single Points of Failure

Independent analysis of the UWMS architecture has identified a structural vulnerability: the system uses what engineers call "largely zero-fault-tolerant" design — a single motor, one fan assembly, and a consolidated controller [4]. This approach saved weight, a priority for deep-space missions where every pound affects fuel budgets. But it also created single points of failure that, when triggered, render the entire system inoperable.

The frozen vent line problem exposes a separate design gap. The UWMS was validated in the thermal environment of low Earth orbit, where the ISS maintains relatively stable temperatures. Deep space introduces far wider thermal swings. The fact that this failure mode manifested on the system's first deep-space flight suggests it was either not modeled in pre-flight thermal analysis or was accepted as a known risk [4][7].

The Burning Smell: What We Know and Don't Know

The unresolved burning odor is, in some respects, more consequential than the toilet malfunction itself. Koch described it as a "burning heater smell" similar to an odor the crew noticed on Day 1 [3]. This recurrence suggests a persistent source rather than a one-time event.

NASA's response followed standard protocol: atmospheric sampling with the onboard gas analyzer (which detected nothing abnormal), visual inspection, and a review of all electrical and thermal telemetry [9]. Flight Director John Honeycutt characterized the public attention as "kind of human nature" while emphasizing that contingency systems worked and the crew experienced discomfort rather than danger [4].

Under NASA's flight rules, an unexplained odor aboard a pressurized spacecraft does not automatically trigger abort criteria. Abort-level events generally require confirmed atmospheric contamination (toxic gas readings above threshold), visible fire or smoke, or structural compromise [13]. An odor with no corroborating sensor data falls into a gray zone — a "manageable anomaly" in mission parlance, requiring monitoring but not immediate action.

That said, the inability to identify the source is itself a data point. A burning smell in a sealed cabin at 200,000 miles from Earth, with no ability to open a window or dock at a station, represents a qualitatively different risk than the same smell aboard the ISS, where crew can retreat to another module and await a resupply ship.

Sixty Years of Space Toilet Problems

The Artemis II incidents sit in a long and well-documented lineage of spaceflight plumbing failures.

Source: NASA mission records, KeepTrack.space compilation

Data as of Apr 7, 2026CSV

Apollo era (1960s–1970s): Astronauts used adhesive fecal bags — a 45-minute process per use [14]. The system was so unreliable that during Apollo 10 in 1969, commander Thomas Stafford interrupted mission communications to report a piece of fecal matter floating through the cabin: "Give me a napkin, quick" [15][16]. None of the three crew members claimed responsibility, creating an unsolved mystery that has persisted for 57 years. Astronauts from later Apollo missions told NASA the bag system was so unpleasant they would rather cut missions short than continue using it [17].

Space Shuttle era (1981–2011): The Waste Collection System improved on Apollo bags with a suction-based commode, but problems persisted. STS-1's charcoal filter clogged, releasing fecal particulates into the cabin. STS-33 experienced a valve malfunction requiring pliers to operate [4].

ISS (2000–present): In May 2008, the Russian ASU toilet in the Zvezda module suffered a pump failure, leaving 13 people — a record crew at the time — sharing a single working commode and the one aboard the docked Space Shuttle [18][19]. NASA ultimately paid $19 million for a second Russian-built toilet [19]. In 2020–2024, the UWMS demonstration unit experienced repeated failures during its ISS checkout [4].

SpaceX Crew Dragon (2021): During the Inspiration4 mission, a tube funneling urine into a storage tank became unglued, leaking beneath the capsule floor onto a fan [20]. A second Crew Dragon capsule, used for the Crew-2 ISS mission, was found to have a similar leak. SpaceX redesigned the system with an all-welded construction to eliminate adhesive joints [21]. Crew-2 astronauts returning to Earth were instructed to use backup "undergarments" — essentially adult diapers — rather than the compromised toilet [22].

How Orion Compares to Crew Dragon and Starliner

The Artemis II toilet failure invites comparison with commercial crew vehicles, though the comparison is imperfect given different mission profiles.

SpaceX Crew Dragon is rated for missions of up to one week in free flight and has logged dozens of crewed missions since 2020. Its waste system is simpler — a curtained-off area with a suction fan — and SpaceX's 2021 redesign with welded joints addressed the adhesive failure that caused the Inspiration4 leak [20][21]. Crew Dragon's primary advantage is operational experience: more cumulative crew-hours mean more opportunities to find and fix failure modes before they become in-flight emergencies.

Boeing's Starliner has flown only limited crewed missions, with its own well-documented technical problems unrelated to waste management [23]. Its toilet system has less public documentation and far less flight time.

Orion is rated for 21 days of crewed habitation and is designed for deep-space missions that neither Crew Dragon nor Starliner can perform [24]. The UWMS is theoretically more capable than either commercial system. But the Artemis II incidents demonstrate that a 21-day rating based on ground testing and partial ISS checkout does not guarantee 21 days of reliable operation in a thermal environment the system was never fully tested in.

The critical distinction is that Crew Dragon and Starliner operate in low Earth orbit, within hours of an emergency return. Orion, on a lunar free-return trajectory, cannot execute a rapid splashdown. After the translunar injection burn on Day 2, the Artemis II crew was committed to a roughly eight-day return path governed by orbital mechanics [25][26]. A toilet failure on Day 3 meant roughly seven days of potential contingency operations — with each crew member carrying only two CCU backup devices [5].

Contingency Protocols and Mission Risk

NASA's contingency planning for waste management failures aboard Orion includes the CCU backup system, which replaces the need for approximately 25 pounds of disposable diapers [5]. The CCUs can vent waste water overboard independently. For solid waste, the crew retains the ability to use the toilet's commode even if the liquid-waste system is offline [4].

The medical risks of extended contingency waste management on a multi-day mission include elevated infection risk from fecal-oral contamination in a confined microgravity environment, where particulates do not settle but remain suspended in cabin air [27]. Crew morale is also a documented concern in long-duration spaceflight literature, though the Artemis II crew has publicly maintained good spirits. Commander Wiseman reported "the sun beaming in all the windows and a beautiful crescent Earth" during the same period the toilet was malfunctioning [28].

NASA has not disclosed whether any crew health telemetry was affected by the waste management issues.

Who Is Accountable?

Collins Aerospace, a subsidiary of RTX Corporation (formerly Raytheon Technologies), holds the primary contract for the UWMS [11][12]. The system's architecture decisions — single-motor design, consolidated controller, vent line routing — were made under that contract. Lockheed Martin, as prime contractor for the Orion capsule, is responsible for overall vehicle integration, including the thermal environment that caused the vent line freeze [29].

The acceptance testing record raises questions about whether known failure modes were adequately addressed before flight. The DFS locked-rotor fault that grounded the ISS demonstration in 2020 is functionally similar to the Day 1 fan jam on Artemis II [4]. The odor filter's failure to meet capacity requirements was documented during ISS testing [4]. Whether these issues were formally flagged in the Orion certification process — and what risk-acceptance decisions were made — is not publicly known.

NASA and its contractors have a clear institutional interest in characterizing the incidents as minor. And in the narrow sense, they are correct: the crew was never in danger, contingency systems worked, and the mission timeline was not affected [10]. But the framing omits context. A "minor" toilet failure aboard the ISS, with its multiple modules, resupply capability, and proximity to Earth, is categorically different from the same failure aboard a four-person capsule on a lunar trajectory with no possibility of early return.

What a Dangerous Version Looks Like

For perspective: a truly dangerous waste management failure would involve contamination of the cabin atmosphere with toxic gases (ammonia from urine breakdown, or hydrogen sulfide from fecal decomposition), blockage of air filtration systems by particulate matter, or — in the case of the burning smell — an actual electrical fire behind the hygiene bay panels. None of these occurred on Artemis II, and sensor data supports NASA's assessment that they did not [9].

The gap between what happened and what could have happened is real, and it provides legitimate grounds for NASA's reassurance. But the gap also highlights what is at stake as NASA plans longer missions — Artemis III will put astronauts on the lunar surface, and eventual Mars missions will require waste management systems to function for months, not days.

Looking Ahead

The Artemis II crew is scheduled to splash down off the coast of San Diego on April 10 [26]. The toilet issues have not altered the mission timeline, and the lunar flyby proceeded as planned [30]. But the data collected during these malfunctions will shape the UWMS redesign for future missions.

The pattern is clear across six decades: NASA has consistently underinvested in and underestimated the engineering challenge of human waste management in space. Each generation of spacecraft has encountered some version of the same problem. The question for Artemis III and beyond is whether the lessons from this flight — a fan jam, a frozen vent line, and an unexplained burning smell — will finally break the cycle, or whether the next crew to the Moon will be reaching for the backup bags too.