China's Shenzhou-23 astronauts harvest rice samples grown from space seeds on Tiangong station

Taikonauts from the Shenzhou-23 crew aboard China's Tiangong space station are trying to grow two successive generations of rice in space. After harvesting first-generation seeds in August, the crew has made considerable progress in what is the country's first multigenerational rice-cultivation experiment in orbit by collecting a new round of rice samples, sowing, and storing them.

China's intriguing project intends to cultivate two back-to-back generations of rice completely under microgravity conditions. The results would enable researchers to analyze how long-term microgravity conditions in space can impact the ability of crops to reproduce and sustain genetic stability. Eventually, the project's goal would be to discover a way to grow food entirely in space without the need to rely on supply missions from Earth. According to the Chinese Academy of Sciences, "this trial represents a critical step toward establishing in situ food production technology for extraterrestrial environments, laying the foundation for sustainable grain production in future deep-space exploration missions, including those on the Moon and Mars."

This is not the first instance of rice being cultivated on the Tiangong space station. Earlier, in 2022, members of the Shenzhou 14 mission demonstrated the world's first-ever complete life cycle rice cultivation in space using the Wentian lab module of the space station. The astronauts cultivated six seeds of rice in orbit for 120 days, yielding 59 first-generation rice seeds in space. These seeds were then brought back to Earth along with the crew members and subsequently propagated on Earth for three generations. That said, despite showing a good ability for reproduction, the seeds displayed poor orientation—rather than sprouting upward, the seeds stayed flat while germinating. Zheng Huiqiong, who's the leader of the research team from the Chinese Academy of Sciences that has been conducting this experiment, attributed this behavior to the effect of microgravity on the plants, referring to the phenomenon as "space syndrome."

The researchers working on this project are also comparing ordinary seeds with the descendants of the rice grown in space in 2022. The comparison could reveal whether previous exposure to the space environment influences how plants adapt to microgravity. The second generation of space rice is expected to achieve maturity during the Shenzou-24 mission. Alongside the rice experiment, the taikonauts recently tested Xiaohang, their robotic companion, to study how it responds to physical touch and boost its motion planning. They also performed evaluations of emergency decision-making and emotional states to help researchers understand how these may alter during extended stays in space.

Despite the progress made by the taikonauts with rice growth aboard the Tiangong space station, it will be a while before we know for sure whether the technology can be transferred to the Moon or Mars. After all, there is a huge difference between the environment on a space station and the one on another celestial body.

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