Longest spacewalk

The longest single spacewalk took 9 hours 6 minutes, and was undertaken by Chinese astronauts Cai Xuzhe and Song Lingdong from the Tiangong space station on 17 December 2024. They opened the hatch on the Wentian airlock at 04:51, and did not return for more than nine hours, closing the hatch behind them at 13:57 UTC.

The two astronauts carried out the spacewalk in Feitian spacesuits, which are based on the Russian Orlan-M suit. Like NASA's EMU spacesuits and the Russian Orlan-M, the Chinese Feitian suit is only designed for around 8 hours of continuous use. This means that astronauts and ground controllers had to carefully monitor each suit's life support consumables as the spacewalkers started to eat into the designed safety margin. The spacewalk involved installing debris shields and repositioning some external equipment, and the exhausting duration of the spacewalk suggests that some element ended up taking much longer than planned.

This record is somewhat complicated by the various different methods used to mark the beginning and end of spacewalks. NASA uses a measurement called "battery time", which starts when the EVA suits are switched over to internal power and ends when they're plugged back into the station umbilical. Roscosmos (and China) generally both use hatch-open to hatch-closed time – marking the start from when the airlock is opened to the exterior and the end from when it is closed again. Other measurements that are sometimes used include depressurize to repressurize time and egress to ingress time.

The previous record holder was a spacewalk carried out by NASA astronauts James Voss and Susan Helms during the construction of the International Space Station on 11 March 2001. NASA gave the duration of this spacewalk as 8 hours 56 minutes, using "battery time". By the same hatch-open–hatch-closed standard used for Tiangong spacewalks, the duration of Voss and Helms' spacewalk was slightly shorter, at 8 hours 54 minutes.