Recently, the scene of Chinese astronauts giving lectures in space has caused controversy on overseas online platforms. In the picture, a cup filled with water placed on the table is circled and enlarged. netizens questioned that neither the water cup used in the experiment nor the water in the cup floated in a weightless environment . "How can a water cup be fixed on the table in a weightless environment? Why can the water in the cup stick to the wall of the cup?" "In the space station of microgravity , the water surface in the water cup cannot remain flat, but will Due to the surface tension of water, is oriented to the spherical surface. "
For this reason, refuting the rumors invited Guo Yun, a senior engineer at the 510th Institute of China Aerospace Science and Technology Corporation, to answer questions for netizens~
The screen shot posted online is. 2021 Shenzhou 13 flight crew information screen when the first class of " Tiangong-1 " started. According to China Space Station 's first space teaching activity. Shenzhou 13 flight crew astronauts Zhai Zhigang, Wang Yaping, Ye Guangfu gave a vivid introduction showing the work and life scenes of the space station, demonstrated cytology experiments, human movement, liquid surface tension in a microgravity environment and other miraculous phenomena, and explained the scientific principles behind the experiment.
So, what is going on with the status of the water cup and water that netizens questioned?
"How do you place a water cup flat on the table?" In fact, a fixing device is used
Guo Yun explained: "The space station or spacecraft is under microgravity conditions, and any objects inside will drift in the air if not fixed. Therefore, for safety and easy to use, water cups, tools, etc. in the space station need to be fixed with buckles, adhesive, nylon buckles or straps, otherwise various objects will float around and cause harm. ”
In Wang Yaping’s video, It can be clearly seen that Wang Yaping took a lot of effort to pick up the water glass from the table, which lasted for nearly 7 seconds. In the picture of the water cup flipping in the air, you can notice a white and transparent raised substance at the bottom of the cup that is in contact with the table. This shows that the water cup is fixed to the table using adhesive or nylon buckles.
"Why is the water in the cup not spherical?" Because in addition to "surface tension", there is also the phenomenon of "wetting"
In addition to the water cup lying flat on the table, another question that netizens question is that the water in the weightless state should tend to be more surface area The smallest spherical shape, but the water in the cup in the screenshot posted online seems to fit the container. Why is this?
Without any external factors, water will form a spherical shape because it is only affected by surface tension and keeps the surface area to a minimum. Guo Yun explained this: " But don't forget a phenomenon explained in middle school physics: 'infiltration', which means that the solid-liquid interfacial tension in the entire water cup 'system' also plays a role. "
Clean The surface of the glass cup is in a "hydrophilic" state. Under the microgravity conditions of space, the infiltration effect will be more obvious. The water will be bound in the glass cup under the infiltration effect, and will not form a sphere but fit together with the glass container.
You can see on the ground that after clean glass is stained with water, even if the glass is turned upside down, a small part of the water will still stick to the surface of the glass without falling off.
Through the above explanation, I believe everyone understands that the doubts about the status of water cups and clean water in the space station are purely rumors. The rumor refuting gentleman once again reminds everyone to think more carefully when encountering problems and not to blindly believe or spread rumors~
