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Surface tension explains stagnant water: China responds to foreign conspiracy theories on space training video
Published: Jul 01, 2022 01:33 PM
China's aerospace institutions explained on Thursday that the water in a cup didn't float in space due to the water surface tension at work in the weightless environment, and the cup was fixed on the table for ease of use, as a science class from China's space station run by taikonauts triggered a wide discussion on overseas social media recently.

Some foreign netizens questioned why a glass of water didn't float in the weightless environment of space and even posed a conspiracy that China has faked its space station. Some domestic netizens also were confused by the discussion. 

China Aerospace Science and Technology Corp, China's aerospace social media "Our Space," and the science and technology communication center of China Association for Science and Technology all posted explanations on the Quora-like platform Zhihu on Thursday to explain the reasons why the water in the glass didn't float in space.        

Science is not that mysterious, and you can explain it in a few pictures and words, "Our Space" wrote via Zhihu. 

The cup is an ordinary cup, and our taikonauts carefully poured the drinking water into the cup, and both the water and the cup are the backup teaching tools for the second science class from China's space station, "Our Space" wrote.

The second science class from China's space station was held on the afternoon of March 23, delivered by Shenzhou-13 crew members Zhai Zhigang, Wang Yaping and Ye Guangfu to students on Earth.

"Our Space" wrote that the water was not used for drinking as taikonauts have to use drinking water bags with a one-way valve structure, noting that it could be dangerous to drink directly using cups in space station. 

Taikonaut Liu Boming drinks water in space. Photo: Our Space via Zhihu

Taikonaut Liu Boming drinks water in space. Photo: Our Space via Zhihu


It also showed a picture which showed how a table tennis ball was able to remain suspended underwater in space. From the picture, we can see that when the taikonauts carefully poured the water into the container, the water did not float due to surface tension, nor would the ping-pong ball in the water to float, but remained in a state of balance inside the container.

Screenshots of an experience showing a table tennis ball suspended under water in orbit Photo: Our Space via Zhihu

Screenshots of an experience showing a table tennis ball suspended under water in orbit Photo: Our Space via Zhihu


Video clips of Wang Yaping and Ye Guangfu preparing the water experiment in space were also released by the account CNSpace_dev on YouTube that netizens could see behind the scenes of preparing a lecture at Tiangong. 

"Education from space is always feasible & should be part of the mission where one of the taikonauts could give a space talk combined with some simple school experiments for the students on Earth. It's about communication between Earth & space," one user named "K Wong" commented.

"The cup has Velcro strips between its bottom and the table. Water stayed in the cup (despite weightlessness) due to surface tension," another user named "Wei Cheng" wrote.

Global Times