The Artemis II crew reported a blinking fault light in their toilet on April 1, the second day of the first crewed lunar mission since Apollo 17 left Earth's orbit in December 1972. NASA associate administrator Amit Kshatriya described it as a controller issue that would take hours to troubleshoot. The backup plan: astronauts would collect urine in bags if the system could not be fixed.
Space.com has an explainer on what scientists hope to learn from the flyby. That is a fine article. It is not this one.
The hardware story of Artemis II is more interesting than a geology field trip. The toilet and the heat shield are both engineering problems that had to be solved before anyone went back to the Moon. The toilet problem has been solved, mostly. The heat shield change is the more consequential fix.
The Universal Waste Management System, or UWMS, is a 3D-printed titanium toilet that Collins Aerospace built under a NASA contract that started in 2015. It is a genuine step up from what Apollo astronauts used: plastic collection bags and funnels so unwieldy that a subsequent NASA report gave waste disposal poor marks. During Apollo 10, astronauts noticed a turd floating through the cabin. During Apollo 8, the crew had to chase blobs of vomit and feces that escaped into the cabin. Ken Mattingly, during Apollo 16, said after using the system that he had once wanted to be the first man on Mars, but the experience had convinced him he was not interested in going on Apollo. The UWMS has airflow. It has a door. Jeremy Hansen, the Canadian Space Agency astronaut on Artemis II, said it is the one place on the tiny spacecraft where the crew can actually feel alone for a moment. The system is not simple: Christina Koch said you have to wear hearing protection when you are in there.
The toilet malfunction on Artemis II is a controller issue, not a fundamental design failure. If it cannot be patched, urine collection goes into bags. Fecal waste can still be handled even without airflow. The system is redundant enough that this is an inconvenience, not a crisis. It is also a reminder that solving basic human biology in microgravity took decades of engineering, and the solution is still not perfect.
The heat shield is a different problem. During Artemis I, the uncrewed precursor mission, the Avcoat ablative shield lost material unevenly. Gases trapped inside the Avcoat blocks built up pressure during the skip reentry profile and cracked the surface, causing char loss. NASA has changed the approach for Artemis II. Instead of a skip reentry, Orion will come in directly. This reduces the time at peak temperatures for trapped gases, but increases deceleration loads on the crew. The agency swapped a thermal problem for a mechanical one. The Avcoat blocks themselves were reduced from 320,000 hexagonal segments in the Apollo era to approximately 180 individual blocks, a configuration change that reflects lessons from Artemis I.
The TLI burn is scheduled for Thursday, April 2. Mission controllers will command the European-built service module to fire for approximately six minutes, sending Orion toward the Moon. The crew will fly within about 4,700 miles of the lunar far side surface, closer than any human has been since 1972. When they come home, they will reenter the atmosphere at approximately 25,000 miles per hour, the fastest reentry ever attempted. The heat shield has to work.
Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen named their spacecraft Integrity. That is either earnest or ironic, depending on your tolerance for astronaut morale. The mission is a milestone: first woman, first person of color, first non-American to orbit the Moon. It is also a hardware delivery problem with a 54-year gap in institutional knowledge to close. The toilet is a nuisance. The heat shield is what you bet your life on.
† Add footnote: "Source-reported; not independently verified."
†† Add footnote: "Source-reported; not independently verified."
