Inset: Victor Glover recounting the Artemis II mission at the Starmus VIII festival in Tenerife. Background: Close up view of the moon with Earth in the background, captured during the Artemis II mission. (Image credit: Inset: Daisy Dobrijevic/Future PLC, Background: NASA)

TENERIFE, CANARY ISLANDS — NASA's Artemis II astronauts were just minutes away from a critical engine burn that would send them toward the moon when an unexpected cabin leak warning threatened to change the course of their historic mission.

"If it had happened five minutes later, we may not have been able to have that burn," Artemis II pilot Victor Glover revealed during an Oct. 18 discussion with Canadian former astronaut Chris Hadfield at the Starmus VIII festival here in Tenerife.

The incident unfolded on April 2, the second day of the Artemis II mission, as the astronauts' Orion spacecraft swooped back toward Earth after traveling some 38,000 miles (61,000 kilometers) away.…