Leonard David's INSIDE OUTER SPACE

China’s Shenzhou-15 space station crew has completed a set of what the country’s space officials tagged as “unprecedented” space walks outside their Tiangong orbiting complex.

Astronauts Fei Junlong and Zhang Lu performed extravehicular activities for about seven hours, exited the station’s Wentian module via an airlock cabin. Fei changed his position with the help of robotic arms while Zhang moved independently by holding railings outside the space station.

During their stint outside of Tiangong they installed “extension pumps” on the Mengtian lab module, and added restraint hardware onto the Tianhe core module.

The twosome also started the cargo out-of-cabin installation task, which will feature a coordinated operation of the devices such as load transfer equipment, cargo airlock module, inner and outer hatch doors, and robotic arms.

Operated by on-orbit astronauts or ground crew, the devices can be either moved outside or inside the cabin according to the requirements of the mission. This technology could improve the efficiency of cargo exchange inside and outside the cabin and reduce astronauts’ EVAs and workload.

Space colleague, Deng Qingming, worked inside the space station to support his crewmates, Fei and Zhang.

Fluid circulation

“Extension pumps have been installed on all the three modules of our space station. They are the pumps in the thermal control circuits, driving the fluid circulation, similar to what the human heart does. They dissipate the heat generated by equipment, just like how our cell phones get hot after being used too much. Then the fluid circulation would help cool the temperature down and dissipate the heat outside,” said Su Nan, the general mechanical designer of the space station extravehicular activity mission.

The pumps need to operate at high speed for a long time, and have to be installed both inside and outside the modules to ensure stable operation of the space station, Su told China Central Television (CCTV).

There is a set of pumps which were [installed inside the module and] launched into space with the module. They had been working before the astronauts installed the extension pumps. If the ones inside stop working in the future, we still have the extension pumps to work. Also, the extension pumps can start operation immediately after installation, and they can also be replaced with new ones,” Su said.

Stable platform

The foot restraints will offer a stable platform for taikonauts to stand on during their follow-up work.

“Foot restraints, with their position fixed on the cabin, are needed when the astronauts work on the outer wall of the cabin. The transfer of the foot restraints is aimed at facilitating work in the future. Two of the foot restraints will be anchored on the outer wall of the cabin, thus they need to be set up in advance,” Su said.

The entire space station is equipped with four foot restraints, Su added, which are usually stored at the exit hatches of the airlock cabin and the node cabin. The astronauts will determine where to install the foot restraints when exiting the capsule based on the needs of the mission.

“There are two foot restraints at the exit hatch of the airlock cabin, which will be installed onto a robotic arm when the astronauts exit the capsule, so they need to be stored there permanently. The other foot restraints are stored at the node cabin. During the space station construction phase, astronauts need to get out the capsule from the node cabin, and the node cabin nears the central position of the space station with three modules, so we made there another permanent storage site,” said Su.

Armrests

“One of the significant features of this extravehicular task is that the astronauts had to move an unprecedented long way, especially for astronaut No. 3, Zhang. He used about 140 armrests during his EVAs, which is pretty challenging,” said Liu Liang, chief designer of the ergonomic subsystem at the China Astronaut Research and Training Center, during a CCTV interview.

During the mission, the other spacewalker, Fei, used robotic arms to move between the modules.

“We reminded him to warm the liquid cooling suit up before the robotic arms transfer, so that he could stay in a relatively comfortable condition. If he only started to adjust the temperature when he felt cold, it would be too late,” said Li Pengwei, chief designer of the extravehicular spacesuit information management and power supply subsystem at the China Astronaut Research and Training Center.

Tracking system

The wide movement range of the mission’s first space walk also required a tracking system that can cover a larger volume of space for longer hours to ensure smooth communications between the astronauts in space and the ground control team.

The second generation of China-made spacesuits is called Feitian, and three sets of extravehicular spacesuits are used in rotation for their EVAs, and can be adjusted in accordance with human parameters like heights and weights.

“Taikonauts are mainly to adjust the size of the upper and lower limbs of the extravehicular spacesuit, particularly adjusting with regarding to their personal height to ensure that the extravehicular suits fit them well,” said Li.

“We chose the extravehicular spacesuits A and B for this round of EVA. Judged from the previous use, Suit B is used the most. We will maximize Suit B’s service life by using it repeatedly,” Li told CCTV. “All our extravehicular spacesuits are in good working condition. According to the overall plan, Suit B will be used to reach its service life to accumulate how many times it is used and how long its service life is, so as to accumulate data for the follow-up development of our products.”

Relay satellites

“We deployed three relay satellites to monitor the three cabins our astronauts used for EVAs. We did that to ensure the largest range and longest period of control and tracking, so that the ground control team could keep communications with the astronauts as much as possible to support their operation at any time,” said Xie Yuan, an engineer at the Beijing Aerospace Control Center.

“Our astronauts completed all the procedures correctly and their operation is perfect. They’ve demonstrated strong operating and coordination capacity. Overall, the three astronauts worked closely and fulfilled these EVAs successfully,” Huang Weifen, astronaut system chief designer of China’s manned space program, told CCTV/China Global Television Network (CGTN).

These were the first EVAs conducted after the completion of the Chinese space station, and also the first spacewalks for Fei and Zhang.

First large-scale space walks

“This is the first large scale EVA mission involving all the three modules after the completion of the space station complex,” said Zhu Guangchen, deputy chief designer of space station system at China Academy of Space Technology.

 

“The astronauts need to pass through the interspace between solar panels and the module while carrying large objects. To ensure the whole mission is completed safely and smoothly, we conducted repeated simulation demos and analysis. Up to now everything is normal and all tasks have been completed as planned,” Zhu told CCTV.

The Shenzhou-15 crew, as planned, will carry out several more spacewalks in the future, said the China Manned Space Agency (CMSA).

Unlocked, installed and tested

Reported Lin Xiqiang, deputy director of the CMSA:

“With the completion of China’s space station, we have now entered the stage of application and development. In the past two months, the Shenzhou-15 crew has unlocked, installed and tested all experiment cabinets on Mengtian lab module. They have started scientific experiments one after the other. Also, the Shenzhou-15 crew has completed first exit of cargo from airlock cabin, which laid foundation for our follow-up tasks.”

The three-person crew has been living in orbit for 70 days since they entered the space station combination on Nov. 30, 2022. Their six-month mission is aimed at wrapping up the last stage of the space station construction and starting the first stage of its application and development.

 

For videos of this first space walk carried out by the Shenzhou-15 crew, go to:

https://youtu.be/y3DmyYFQE0g

https://youtu.be/Fauwz8mutyw