China's Shenzhou-19 crew has revealed successfully handling a lock failure during what became a record-breaking nine-hour spacewalk last December – the longest single extravehicular activity (EVA) in history.

The mission's post-landing disclosures highlight China's growing capabilities in orbital troubleshooting.

Astronaut Cai Xuzhe, now China's most experienced spacewalker with five EVAs, described how the crew responded to a payload adapter partially jammed during previous equipment installation.

"The payload was deployed through the cargo airlock. The external adapter normally has two locking mechanisms. But while one lock disengaged automatically via the robotic arm as designed, the secondary lock failed to release. This partial failure left half of the mechanism still attached to the station wall. We had to improvise a tool to manually disengage the remaining lock," Cai said.

The critical repair occurred during the mission's first spacewalk on December 17, 2024. After completing primary tasks including space debris shield installations, Cai, assisted by crewmate Song Lingdong, used the station's robotic arm to reach the malfunction site.

The operation faced intense time pressure as it needed to be completed during limited sunlight periods, with only about 40 minutes remaining in the final suitable window. At this point, both astronauts had already spent over seven hours working in China's second-generation Feitian spacesuits.

When asked about operating at the suits' endurance limits, Cai expressed confidence in the systems, detailing how they continuously monitored oxygen levels throughout the extended EVA.

"Our oxygen supply was well within safety margins. The suit carries two tanks – primary and backup. Even if the primary tank were fully depleted, the backup would sustain us. Activating the backup would require aborting the EVA, but we never even approached that threshold. We maintained complete operational awareness throughout," Cai said.

The successful troubleshooting demonstrated the spacesuits' reliability and China's autonomous problem-solving capabilities in space. Mission controllers emphasized that the nine-hour EVA not only set a new Chinese record but surpassed all previous international single-spacewalk durations.

"This achievement demonstrates three key points: first, the absolute reliability of our spacesuits; second, our operational capacity to sustain nine hours of continuous extravehicular work; and third, it showcases the maturity and self-assurance of China's crewed spaceflight technology," Cai said.