At 15:40 on March 23, 2022, the second lesson of "Tiangong Classroom" was held on the China Space Station. In the about 60-minute lecture, The Shenzhou 13 astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu cooperated with each other to teach, which was also the third time that Chinese astronauts taught in space.
On December 9, 2021, the Shenzhou 13 crew conducted the first space lecture, and many people were deeply impressed by the wonderful and rich class.
The "Tiangong Classroom" activity continued to adopt the method of dialogue between heaven and earth, and astronauts demonstrated space "ice and snow" experiments, liquid bridge demonstration experiments, water and oil separation experiments, space parabolic experiments in orbit, and introduced and displayed space science facilities. In addition to explaining the scientific principles behind the experiment, the astronauts also answered the questions of ground students in this Tiangong class, satisfying the children's curiosity about space science knowledge.
Space parabolic experiments, ice piers exiting
As a blind box was taken to the Chinese space station, on the occasion of the Beijing Winter Olympics, the Shenzhou 13 crew astronauts got the ice pier to make them happy, and this time also invited this "special guest" to participate in the class to demonstrate Newton's laws.
Teacher Wang Yaping first let the ice pier turn over a few heels, and then threw out the ice pier, we saw that in space, it will not fall like the earth, but in the original direction of uniform speed.
Space "ice and snow" experiments
As we all know, crystallization precipitation occurs only when the solution reaches a saturated state. If the solution does not reach saturation, it will continue to dissolve and will not crystallize.
Space "ice and snow" experiments demonstrated the crystallization of supersaturated solutions in weightless states. The supersaturated sodium acetate solution forms a liquid ball, which emits a lot of heat during the rapid crystallization process, and the liquid ball crystallization looks like an "ice ball" and is actually a "hot ball".
In life, mixing it with white vinegar and baking soda will also make the liquid crystallize.
Liquid bridge demonstration experiment
The tension of liquids in space and on the ground is different. Teacher Wang Yaping has used many methods to show the tension of liquids in space, this time she took two liquid bridges with water balls, closed them and then pulled them apart, and found that in the microgravity environment, the tension of the liquid is enough to maintain the water between the two objects, pulling into a "bridge" of about 10cm.
Since the space station is a microgravity environment, a longer stable liquid bridge cannot be obtained on the ground due to gravity factors, and the length of the liquid bridge will not exceed 5mm. High voltages are applied to the ground to form deionized water-liquid bridges.
Water-oil separation experiments
We found that water and oil delamination disappeared in weightless environments. To separate water and oil, it is necessary to bring centrifugal force through rotation, similar to ground gravity to separate water and oil.
After the test, the astronauts also answered some interesting questions raised by their ground classmates.
How is the timing set in the space station?
The space station circles the earth in 90 minutes, but the Tiangong still uses Beijing time.
How is the moon seen in space different from Earth?
Because there is no atmospheric interference in space, the moon seen is brighter and larger than Earth.
Can water be boiled in the space station?
The water in the space station can't be boiled!
In space, will the space station be resisted?
Although the orbit is very high, the space station will be subject to resistance in space, so the space station needs to have the power to maintain the orbit of the space station.
Can the ground be operated directly to obtain experimental data?
Experimental data can be transmitted to scientists on the ground in real time.