Do you still remember the lesson from China's Tiangong space station last year? On March 23, astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu gave another one! It was live—streamed worldwide. What fun experiments did they do this time?
A bridge of water
How do you build a "bridge" with water? It's hard to do it on Earth. But in the space station, with little gravity, it's quite easy!
In the lesson, Wang Yaping first made two water balls on two plates, then let them touch each other. Next, Wang pulled the two plates away, and the water between them didn't break. It became a "bridge"!This is because the surface tension( 张 力 )of water is not affected by gravity in space. The surface tension keeps the "skin"of the water strong so that the bridge doesn't break.
Separate water and oil
If we mix oil and water in a bottle on Earth, we can separate them quickly because they have different densities(密度). Gravity brings the water down while the oil stays on top. However, if you do this in the space station, with no gravity, oil and water will mix together.
How can we separate them, then? In the lesson, Ye Guangfu rotated spun the bottle to create centrifugal force. With this man—made gravity, the heavier water and the lighter oil are separated.
