27th December 2025 - (Beijing) One of four mice that travelled aboard China's Shenzhou‑21 spacecraft has successfully given birth to healthy offspring after returning to Earth, the Technology and Engineering Center for Space Utilisation at the Chinese Academy of Sciences (CAS) confirmed on Friday. The four animals were launched on 31 October as part of an experiment to study survival and adaptation in the space environment. They were housed in a purpose‑built small‑mammal habitat on board China's space station throughout the mission.
Following their return on 14th November, one female mouse became pregnant and subsequently gave birth to nine pups on 10 December. Six of the litter have survived and are developing well, a rate described by researchers as within the normal range.
Scientists report that the mother is showing typical maternal behaviour, while the so‑called "space mouse offspring" are active and exhibit strong vitality. The team is closely monitoring the animals, which are now being raised under controlled laboratory conditions.
According to Wang Hongmei, a researcher at the CAS Institute of Zoology, the outcome demonstrates that short‑duration spaceflight did not impair the reproductive capacity of the mice. She said the case provides a rare and valuable dataset for examining how the space environment influences early mammalian development.
The mission, however, was not without complications. Changes to the return schedule of the Shenzhou‑20 mission led to an extended stay for the mice and created an unexpected risk of food shortage. In response, the ground team activated an emergency protocol, rapidly testing multiple contingency plans and running verification experiments on Earth.
By making use of an external water supply port on the space station's feeding system, researchers, working with astronauts in orbit, were able to pump water directly into the mice's habitat.
To address the food issue, scientists screened potential substitutes from the astronauts' own menu - including compressed biscuits, maize, hazelnuts and soy milk - and carried out ground trials to confirm the animals would accept the new diets and suffer no ill effects. After assessment, soy milk was chosen as the most suitable emergency food.
Throughout the mission, an artificial‑intelligence‑based behaviour analysis system, developed in advance, tracked the mice in real time, recording their movement, feeding and sleep patterns. This allowed researchers to accurately forecast food consumption and supply levels, providing critical data for decision‑making during the emergency.
Looking ahead, the team plans comprehensive studies on the pups, charting their growth and development, and analysing physiological and pathological changes. Scientists will also follow their reproductive performance and aim to observe a second generation descended from the space‑flown mice.