Chinese astronauts conduct record-breaking 9-hour spacewalk outside Tiangong space station (photos)

Two Chinese astronauts just secured a spot in spaceflight history.

Cai Xuzhe and Song Lingdong, part of China’s three-person Shenzhou 19 mission, spent more than nine hours spacewalking outside the Tiangong space station from late Monday night (Dec. 16) through Tuesday morning (Dec. 17), according to officials with China’s Manned Space Engineering Office (CMSEO).

That broke the previous duration record for a single extravehicular activity (EVA), which was eight hours and 56 minutes, according to NASA. That mark was set by NASA astronauts James Voss and Susan Helms outside the International Space Station back in March 2001.

This week’s EVA was the first for the Shenzhou 19 mission, which arrived at Tiangong on Oct. 29 for a six-month stay.

Related: Watch Chinese astronauts fix Tiangong space station solar wing in 8-hour spacewalk (video)

During the spacewalk, Cai and Song — along with crewmate Wang Haoze, who remained inside Tiangong — “worked closely together, and with the support of the space station’s robotic arm and ground scientific researchers, completed the installation of the space station’s space debris protection device, the inspection and disposal of extravehicular equipment and facilities, and other tasks,” CMSEO officials said in a WeChat update on Tuesday.

“The extravehicular activities were a complete success,” they added, also noting that Song, 34, “became China’s first astronaut born in the 1990s to conduct extravehicular activities.”

According to SpaceNews, the spacewalk began on Monday at 11:51 p.m. EDT (0451 GMT on Dec. 17), when Cai, the Shenzhou 19 commander, exited Tiangong’s Wentian module. Song followed suit more than 90 minutes later, at 1:32 a.m. EDT (0632 GMT).

Both astronauts went back inside Wentian at 8:57 a.m. EDT (1357 GMT) on Tuesday, CMSEO officials wrote in the update. Those numbers put the EVA’s duration at nine hours and six minutes, meaning it broke the old record by just 10 minutes.

The record-setting EVA was the 17th overall outside of Tiangong, according to SpaceNews. The space station’s core module, called Tianhe, reached orbit in April 2021. Two more modules — Wentian and Mengtian — arrived in July 2022 and November 2022, respectively, completing the T-shaped orbital outpost.