Fifteen minutes. That is how close NASA's Artemis II mission came to being reshaped by a single warning message: "cabin leak suspected."
Pilot Victor Glover described the episode publicly on October 18, in a conversation with former Canadian astronaut Chris Hadfield at the Starmus VIII festival in Tenerife, in Spain's Canary Islands — the fullest account yet of a tense moment that had previously been mentioned only in passing during the mission itself.
"If it had happened five minutes later, we may not have been able to have that burn," Glover said.
A warning at the worst possible moment
Artemis II launched on April 1, 2026, carrying commander Reid Wiseman, pilot Glover, and mission specialists Christina Koch of NASA and Jeremy Hansen of the Canadian Space Agency — the first crew to travel to the Moon in more than half a century. Rather than heading straight for deep space, the Orion spacecraft first completed a highly elliptical orbit of Earth, giving the crew and mission control a full day to test life-support, communications and handling systems before committing to the lunar journey. Once the translunar injection (TLI) burn was performed, there would be no quick way back.
On April 2, the mission's second day, Orion had travelled some 38,000 miles (61,000 kilometres) from Earth and was swooping back toward the planet for the burn, which was timed for its closest approach — roughly 100 miles (160 kilometres) above the surface, where the spacecraft was moving fastest. Glover recalled Hansen looking out the window as the Earth filled the view and remarking: "I think we're going to run smack dab into the middle of Earth." The low pass also took Orion through a region crowded with orbital debris and satellites, with higher radiation to match.
That was when the warning appeared: a possible leak in the cabin, with about 15 minutes left before the burn.
The decision
A cabin leak is among the most serious alerts a crew can receive, because a genuine loss of pressure can become life-threatening quickly. But the timing forced a brutal calculation. If the warning was real, the crew would need to scrub the burn, get into their spacesuits and come home within about a day. If it was false, delaying to investigate could mean missing the narrow window for the Moon altogether.
"Determining whether it was real or not was a big deal," Glover said. Working with mission control, the crew checked the capsule's data — and the warning proved to be a false alarm, as flight director Judd Frieling confirmed at a media briefing later that day. Hansen had already alluded to the scare in a live video during the flight, saying the message "grabs your attention" precisely because the alternatives diverge so completely.
With the go-ahead given, Orion fired its main engine for five minutes and 50 seconds at 7:49 p.m. EDT on April 2, accelerating to about 24,500 miles per hour and setting course for the Moon, on a journey that would carry humans farther from Earth than ever before.
Why it matters
The revelation adds human texture to a mission that will serve as the template for NASA's return to the lunar surface with Artemis III and IV, for which the agency has been detailing lander plans with SpaceX and Blue Origin ahead of targeted landings later this decade. It also illustrates a principle veteran astronauts repeat: deep-space missions are won or lost in the minutes when a crew must decide whether an alarm is a malfunction of the sensor or of the spacecraft. In this case it was the sensor — and the margin, Glover's account makes clear, was about five minutes wide.
*Reporting based on Space.com's account of the Starmus VIII discussion and contemporaneous NASA briefings.*