Astronauts aboard China's Tiangong space station played a game of "ping-pong" using a droplet of water instead of a ball during a space lecture on Wednesday, captivating students from Hong Kong and Macao with a vivid demonstration of fluid mechanics and material science in microgravity.
The Shenzhou-23 crew, commander Zhu Yangzhu, spacecraft pilot Zhang Zhiyuan and Hong Kong's first payload specialist Lai Ka-ying, delivered the Tiangong Class session specially designed for students in the two special administrative regions.
During the water-ball ping-pong demonstration, Zhu, who first performed the experiment during the Shenzhou-16 mission in 2023, showed that a racket covered with a towel could repel the ping-pong-like droplet. Zhu explained that the trick lies in the towel's hydrophobicity and the micro-nano structure it forms can easily repel water. He then teamed up with Lai for a friendly "match" using the towel-covered bats.
"A seemingly light-hearted and fun water-ball ping-pong game contains multiple scientific principles in fluid mechanics and material science. From the first demonstration by the Shenzhou-16 crew to our reproduction of the experiment today, we hope to turn abstract knowledge into tangible, interesting reality and plant the seeds of scientific exploration in every student," Zhu said. "A tiny droplet of water, hovering 400 kilometers above Earth, symbolizes the scientific dreams of Hong Kong and Macao taking root in the nation's space program. Hong Kong and Macao have long been deeply involved in the country's space endeavors, the Tianyun camera, developed by a joint team of scientists from Hong Kong and the mainland, is a vivid example of this collaboration. The mainland has opened the door to space exploration, while Hong Kong and Macao contribute their own scientific strengths to the national mission. Hong Kong, Macao, and the Tiangong space station gaze upon each other from afar, united in heart and purpose. Together, we journey toward the boundless starry sea that all Chinese people dream of," she said.
The class also featured other demonstrations, including a floating bauhinia flower clay sculpture, Hong Kong's floral emblem, and an introduction to the Tianyun camera, a space station instrument developed with input from a Hong Kong research team.
The event was jointly organized by the governments of the Hong Kong SAR and the Macao Macao SAR, along with the China Manned Space Agency. More than 200 primary and secondary school students from the two regions attended the ground class at Tsuen Wan Public Ho Chuen Yiu Memorial College in Hong Kong, Lai's alma mater.
The session was broadcast live to primary and secondary schools across both regions, as well as through official online platforms and local broadcasters.
Astronauts play water-ball ping-pong in space lecture for Hong Kong, Macao students
