China performs second EVA in two weeks, Chang Zheng 2D launch

by Adrian Beil

China conducted another EVA outside of their Tiangong Space Station, preparing the station for the future and practicing safety mechanisms for upcoming EVAs. They also launched the Yunhai-1-03 payload from Jiuquan on board a Chang Zheng 2D rocket.

Shenzhou-14 Mission Conducts Second Spacewalk

On Sept. 17, Chinese taikonauts Chen Dong and Cai Xuzhe started the second spacewalk of the Shenzhou-14 mission, just two weeks after the first. Taikonaut Liu Yang operated the robotic arm from inside the Tianhe Core module. 

The spacewalk started at 05:35 UTC with the opening of the Wentian airlock. Wentian was the first science module that was launched earlier this year. It is not only providing science capabilities to the station but is also equipped with an airlock to initiate EVAs.

About two hours after the initial airlock opening, Cai Xuzhe and Chen Dong exited the airlock for the installation of a foot-stop, which can be used to fix astronauts to the robotic arm, and the installation of a new emergency handle that can open the hatch door from outside. 

Also included in this spacewalk was the installation of additional pumps which will help the station´s thermal control system. The full duration of the EVA was four hours and 12 minutes, with Chen Dong performing his second spacewalk on the Shenzhou-14 mission, while Cai Xuzhe performed his first of the mission. He stayed inside during the last EVA.

In the later stages of the EVA, they also performed a test of rescue operations with Cai Xuzhe releasing both hands from the rail to simulate an emergency. Chen Dong then performed a simulated rescue operation. This is a simulation of the case that one of the astronauts would lose consciousness during an EVA.

Overall, the spacewalk was performed faster than the initial schedule, with the initial duration being planned for six hours.

The Tiangong space station is entering a continuously crewed period with the Shenzhou 14 mission. The next milestone will be the installation of the Mengtian science module, which is planned for October 2022. 

Earlier this year, the Wentian module was launched on July 24. It sparked international pushback, as the Chinese Chang Zheng 5B core stage did not deorbit in a controlled way, but instead was left in orbit and made an uncontrolled reentry a few days later. This was not a vehicle failure, but part of the design of the rocket, which has no installed control after deploying the payload into orbit.

Chang Zheng 2D Launches Yunhai-1-03

A few days after the EVA, the Yunhai-1-03 payload was launched from Jiuquan. It launched on Sept. 20 at 23:15 UTC on a Chang Zheng 2D and was labeled as an atmospheric, marine and space environments, disaster prevention and mitigation satellite. While this is the official given purpose, this might be a placeholder to not reveal the true intention of the satellite. The weight of the payload, and exact technical specifications, remain unknown.

Chang Zheng 2D ascends from Jiuquan

According to CASC, the preparation of the rocket for launch, after the arrival of the payload, only took 11 days.

It was built by the Shanghai Academy of Spaceflight Technology (SAST), as was the rocket for this launch. The payload was deployed into a 754 x 776 km orbit with an inclination of 98.5°.

The Yunhai payloads are a series of meteorological satellites that usually go to a Sun-synchronous orbit. The Yunhai-1-02 payload was launched on Sept. 25, 2019, on the same rocket configuration as today´s launch. The first Yunhai-1 was launched in 2016.

The rocket for this launch is the Chang Zheng 2D. It stands 41 meters tall with a diameter of 3.35 meters and a liftoff mass of 232,250 kg. It uses the hypergolic mixture of unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (N2O4), which is a common combination used by the older Chang Zheng rockets, such as the Chang Zheng 2, 3, and 4.

The top of the Chang Zheng 2D rocket before launch

The first stage stands 27.91 meters tall and makes up most of the size and mass of the rocket. It is lifted by four YF-21C engines which produce 2,961 kN of thrust, with a specific impulse of 260 seconds.

After the first stage is done, the second stage takes over. It stands 10.9 meters tall with a mass of 52,700 kg and a YF-22C main engine that powers it. It is assisted by four YF-23C vernier engines that help to steer the rocket during this stage of the flight. The second stage produces 742 kN of thrust.

This was the 65th mission of the Chang Zheng 2D, its eighth flight in 2022, and the 64th successful flight of the rocket. 

(Lead image: The second Shenzhou-14 spacewalk)

Related Articles