A dozen of handpicked Chinese astronauts, or taikonauts as they are called, are set to explore new horizons in space in four manned flight missions within two years. In the first of these missions, three taikonauts aboard the Shenzhou-12 spacecraft have already successfully made it to space.

The flight crews for Shenzhou-12 to Shenzhou-15 were selected in December 2019. China has picked four teams for different missions. Each team is led by an experienced captain, who will command another two taikonauts.

For Shenzhou-12 mission, three taikonauts, namely Nie Haisheng, Liu Boming and Tang Hongbo, became the first to enter the Chinese space station.

"I think the trio is a great combo," said Huang Weifen, deputy chief designer of the astronaut system of China's manned space program. "We chose Nie as the captain for his two-time space flight experience and Liu Boming for his previous experience in extravehicular activity, while Tang is the backup taikonaut for Shenzhou-11 mission and he excelled in every area."

The selection has been made based on aspects such as experience, age, individual characters, physical performance and mental health. The synergy or compatibility among different members is also a big factor.

Selected from 'best of the best'

The qualification criteria includes basic, physical, mental and overall evaluations. "There are about 43 aspects including age, height, education and professional background just in basic evaluation," said Huang.

She said physical evaluation is about clinical and physical functions, such as cardio-pulmonary function and endurance to the space environment. There are 17 physical checks just to test endurance and adaptation to the space environment.

Testing of the vestibular function is also one of the physical checks. Huang explained that astronauts usually experience a unique physical reaction in the orbit during the first three days in space, similar to carsickness or seasickness. Candidates who have weak vestibular function can become very dizzy and even vomit.

"It's incredibly difficult to become an astronaut," Huang said.

After over two decades of practice, China has set up a complete process to select taikonauts who can work as pilot astronauts, spaceflight engineers or payload specialists.

"The pilot astronauts need to meet the strictest requirements, and they are chosen from active aviators," according to Huang. She said engineers and payload specialists have different requirements, less strict but still many.

Huang said only clinical medical requirement for selection has over 120 clauses, each of which has multiple medical requests that a candidate must meet.

"It's a process to select from 'the best of the best,'" said Huang.

Excruciating training

Huang led the team to develop over a hundred types of training in eight categories in various fields, such as medicine, physics, psychology, science and engineering. She also trained the Shenzhou-12 taikonauts under water to mimic the microgravity environment as there are extravehicular activities for the mission this time.

"They are trained for four hours each time under water, donning spacesuits over 200 kilograms," said Huang. "It's grueling for our taikonauts."

"In the early sessions, Tang said he could not even hold chopsticks after the training," Huang said. Tang has never been to the space before.

The astronauts are exposed to the pull of hypergravity when spaceships ascend and return. During the hypergravity period, the blood moves to the legs, causing possible loss of vision and consciousness. So, the training on tolerance to hypergravity, or high-G training, is also essential.

Huang said all male and female taikonauts have to pass the 8G criterion, which means they should be able to bear eight times the gravity force of their own body weight. "The taikonauts go through it once every half a year."

"As long as they are professional astronauts, it's their duty to keep going through the training, ready for the mission calls, until the moment they retire," Huang said.