Orbiting our planet, China’s Tiangong space station serves not only as a home for astronauts but also as a space-based science laboratory.
One fascinating area of study on Tiangong is in the life sciences. These experiments help researchers understand how living things survive in space. Let’s dive into a few examples of these projects.
Zebrafish: the ultimate space swimmer
Zebrafish are tiny fish with zebra-like stripes, and they grow and reproduce quickly. Scientists often use them in experiments to study biological processes and diseases because they share a 70 per cent genetic similarity with humans and are small enough to be brought to space.
In April 2024, the astronauts of the Shenzhou-18 spacecraft took four adult zebrafish to Tiangong for China’s first aquatic ecological research project in space.
Scientists studied the zebrafish to see how vertebrates grow, live and reproduce in space. This could help them better understand how living in space affects humans.
The “fish astronauts” were selected from 200 candidates. They had to be healthy, emotionally stable and flexible in adjusting to new environments.
In an enclosed aquarium aboard Tiangong, the zebrafish could not discern up from down when experiencing the weightlessness of space. They swam in strange ways and flipped upside-down.
Even so, they thrived for 43 days, setting a record as the longest surviving fish in space. They even reproduced and laid eggs while they were on Tiangong. The astronauts sent the fish eggs and water samples back to Earth for further study.
This past April, the Shenzhou-20 spacecraft brought more zebrafish to Tiangong to study how weightlessness affects their bones and muscles.
Planarians: space regenerators
The Shenzhou-20 crew also carried some invertebrates, called planarians, to Tiangong. Planarians are flatworms that have strong regenerative abilities, allowing them to regrow new body parts from cut sections (see graphic).
Scientists cut the planarians into pieces, placed them into specially designed chips and sent them to the space station for research. They wanted to understand how planarians regrow new body parts in space compared with Earth.
Hopefully, this will also inspire scientists with ways to help humans heal better – both on Earth and in space.
Students can get involved
Space experiments are not exclusive to astronauts and scientists – students in Hong Kong have also contributed to Tiangong experiments.
For example, four secondary school students suggested the idea of studying silkworms in space.
In 2016, the Shenzhou-11 spacecraft carried six silkworms aboard the Tiangong-2 space laboratory, which was a temporary facility testing the technology needed to build Tiangong. The experiment investigated how silkworms grow and spin cocoons in weightlessness.
In April, hundreds of primary and secondary school students grew plants using seeds returned from Tiangong and compared their development with ordinary seeds.
By joining competitions or educational programmes, students can propose ideas linked to real space missions.
To learn more about Tiangong and its experiments, visit the Hong Kong Space Museum’s special exhibition “A Voyage to Space: China’s Manned Space Expedition”. You will see a model of Tiangong and learn about experiments conducted aboard the floating laboratory. The exhibition runs until April 27, 2026, and is free for all.
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