Astronauts conduct second Chinese space station spacewalk

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HELSINKI — Chinese astronauts Nie Haisheng and Liu Boming embarked on a second Shenzhou-12 spacewalk late Thursday to carry out work on a space station robotic arm.

Shenzhou-12 mission commander Nie opened the hatch of the Tianhe module at 8:38 p.m. Eastern Aug. 19 to begin a planned near seven-hour extravehicular activity, the China Manned Space Agency (CMSA) said.

The pair, wearing second generation Feitian (“flying to space”) extravehicular mobility suits, completed installing foot restraints and an extravehicular working platform to the large robotic arm. Chinese media outlets streamed footage of the EVA.

The excursion was supported by astronaut Tang Hongbo inside Tianhe, the 16.6-meter-long, 4.2-meter-diameter space station core module which launched April 28.

The EVA also included work on a panoramic camera, installing a toolkit, adding a pump set for the Tianhe thermal control system and other apparatus in preparation for the arrival of two further modules in 2022. The EVA was completed at 2:33 a.m. Friday, around an hour ahead of schedule.

The Shenzhou-12 crew have been aboard Tianhe since June 17. They are expected to return to Earth within a month, ahead of arrival of the Tianzhou-3 cargo supply mission. A first Shenzhou-12 spacewalk was conducted July 3 by Liu Bomng and Tang Hongbo.

The astronauts have carried out a range of activities and experiments in preparation for future missions. Recent work includes installing a refrigeration unit for medical samples, assembly of a space centrifuge, activating a magnetic levitation experiment, blood sampling and testing a hazardous trace gas removal subsystem.

Chinese astronauts Nie Haisheng and Liu Boming during the second Shenzhou-12 spacewalk.
Chinese astronauts Nie Haisheng and Liu Boming during the second Shenzhou-12 spacewalk. Credit: CNSA/BACC

Space station construction plans

The Long March 7 rocket to launch Tianzhou-3 arrived at Wenchang spaceport earlier this week and is expected to launch around September 20. Tianzhou-3 will deliver supplies for the October Shenzhou-13 crewed mission. 

Preparations for Shenzhou-13 are underway at Jiuquan, northeast China, where a Long March 2F rocket has been readied in advance in case of need for an emergency launch to Tianhe.

Tianzhou-2, which delivered supplies to Tianhe for Shenzhou-12, is expected to remain docked to the core module beyond the deorbiting of Shenzhou-12. It will then undock from Tianhe’s aft port and dock with the forward docking port and conduct transfer propellant testing with Tianhe. 

The 13,000-kilogram liftoff mass Tianzhou-2 will then be used as a test unit for the robotic arm to manipulate modules as part of space station construction. Tianhe will be joined in orbit by two experiment-hosting modules, named Mengtian and Wentian, in 2022.

A day ahead of the spacewalk CMSA released orbital parameters for Tianhe of 379.7 by 396.85 kilometers with an inclination of 41.35 degrees and a speed of 7.68 kilometers per second.

Yang Yanbo, deputy commander of the Shenzhou-12 mission at the Beijing Aerospace Control Center, told Chinese media that teams on the ground are monitoring the space environment and are ready to conduct collision avoidance maneuvers.

Shenzhou-12 is the third of an intensive series of 11 missions for construction of the three-module Chinese space station. Named Tiangong, the overall complex is planned to be completed by the end of 2022.

Tiangong will be joined in orbit by Xuntian, an optical Hubble-class space telescope, around 2024. The Chinese space station could also be expanded from three to six modules if main phase construction proceeds as planned.