Hong Kong astronaut shows how towels behave in microgravity during Tiangong class
Shenzhou-23 crew held a live Tiangong Class for Hong Kong and Macao students, with astronaut Lai Ka-ying demonstrating water surface tension in microgravity.
Students from Hong Kong and Macao got a live science lesson from orbit on Wednesday as the Shenzhou-23 crew conducted a Tiangong Class from the space station. The session, hosted at Tsuen Wan Public Ho Chuen Yiu Memorial College in Hong Kong, allowed hundreds of students to interact directly with the astronauts.
Lai Ka-ying, the first Hong Kong-born astronaut to fly to space, led a demonstration on how water behaves in a microgravity environment. Wringing a wet towel, she showed that water did not drip but clung to the fabric, forming a glove-like shape around her hand.
"This is because in a microgravity environment, water's surface tension plays a dominant role," Lai explained. "Water molecules hold tightly together and adhere to the surface."
She also clarified that astronauts do not actually wring towels in space. "It's easy to accidentally shake off small water droplets, and collecting them would be quite troublesome," she said, noting that the correct approach is to let towels air-dry naturally or seal and dispose of them.
Commander Zhu Yangzhu and astronaut Zhang Zhiyuan also participated in the interactive session. The three crew members were launched aboard the Shenzhou-23 spacecraft on May 24.