The Shenzhou-21 crew will carry out in-orbit scientific experiments involving mice during their stay on China's space station, according to the China Manned Space Agency (CMSA).

Four mice, two males and two females, will be transported to the space station aboard the Shenzhou-21 spaceship and raised in orbit, CMSA spokesperson Zhang Jingbo said at a press conference held on Thursday, one day prior to the launch of the Shenzhou-21 mission.

Noting that this will be China's first scientific experiments involving rodent mammals in space, Zhang said the in-orbit experiments will focus on examining the effects of space conditions, such as microgravity and enclosed space, on the behavior of the animals.

Subsequently, the mice will return to Earth via a spaceship, and further scientific research will be carried out to explore the stress response and adaptive changes of multiple tissues and organs of mice in the space environment, Zhang added.

"Our ultimate goal is to understand how the space environment affects long-term human spaceflight," explained Li Tianda, associate researcher at the Institute of Zoology, Chinese Academy of Sciences. "We use mice as a model organism to understand humans and ultimately serve humanity."

With approximately 95 percent genetic similarity to humans, mice are excellent model organisms.

Liu Fangwu, associate researcher at the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, described the sophisticated life support system. The rearing device sent to the space station with Tianzhou-9 provides gas purification, oxygen supply, and on-orbit monitoring for the mice. The mouse experimental unit traveling with Shenzhou-21 provides food, water, lighting, imaging and waste collection.

One unique challenge was waste management in microgravity. "In the space microgravity environment, droppings can float around, so we designed a small automated waste collection system – essentially a directional airflow to move the waste to a designated module," Liu explained.

The Shenzhou-21 mission will conduct further cutting-edge research, including a study on amino acid homochirality.

"Life on Earth has undergone billions of years of evolution, and ultimately, without exception, all life has chosen left-handed amino acids as the material foundation for protein construction," Wu Yile from Ningbo University's Institute of Drug Discovery Technology told CGTN. "The question we want to explore is whether this choice is related to Earth's gravitational conditions."

Wu added that the space station's genuine microgravity environment provides ideal conditions for the study.

During their stay in orbit, the Shenzhou-21 crew will carry out 27 new scientific and application study projects, focusing on key scientific issues across several fields, including space life science and biotechnology, aerospace medicine, space materials science, microgravity fluid physics and combustion, and new space technologies.

(Sun Ye and Zhu Yingming contributed to the story.)