Produced by: China Science Expo SELF Ge Zhi Dao Pulpit
Introduction: On the surface of the earth, because of the existence of gravity, we drive cars, airplanes, rockets, all need huge thrust, but in space, the weight of an ant can push hundreds of tons of aircraft, it is a micro force. What can Micro Force do? How do scientists capture such a small amount of power? Yu Xilong, a researcher at the Chinese Academy of Sciences, performed the magic of micro-force on the stage of the SELF forum.
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--- Guest Introduction ---
Yu Xilong
Researcher, Institute of Mechanics, Chinese Academy of Sciences
The following is a condensed compilation of Yu Xilong's speech:
How small is the micro force?
The micro force is a very small force, so what is the role of this tiny force?
When many children have birthdays, a very warm picture is to blow out the candles, blowing out the candles should be a very simple thing, one, two, three mouths may blow out the candles. But what if this happened in space?
Tiangong-2 is a space station in our country, it operates in a vacuum environment 393 kilometers above the earth, but in fact, due to the action of vacuum microgravity and atmospheric resistance, its orbit will slowly decline, and the resistance it is subjected to is about 4.6mN, 4.6mN is a very small force, it is difficult to contact such a small force in daily life.
Yu Xilong described this force in a figurative metaphor, the picture is ten ants, the weight of one ant is about 50 milligrams, the weight of ten ants is the size of the micro-resistance of Tiangong-2, in fact, this force is very small, but such a small force can make the space station drop about 70 meters a day.
How the booster works
So how do you make space run at such a high altitude? The yellow part in this photo is a small thruster, and its role is to generate a force that can counteract the resistance and make the spacecraft stand steadily at an altitude of 393 kilometers, so how does this small thruster work? Or how does it work?
At present, there are three kinds of small thrusters commonly used, one is the so-called cold air thruster, it is actually very simple, that is, a high-pressure gas cylinder is filled with high-pressure gas, when a valve gas is discharged, it can produce thrust, and the effect of this thrust is similar to that of us blowing a breath. Then the other is the chemical thruster, which works by using the high temperature and high pressure gas produced by the combustion of chemical substances to spew out and generate thrust. There is also an electric thruster, which is a relatively complex type of thruster, which actually produces thrust by accelerating the ionized air through a magnetic field.
How do scientists measure tiny thrusts?
At the scene, researcher Yu Xilong invited the audience to participate in the experiment on stage, using the thrust bench that measures the force to test how much force the blowing force is.
Under atmospheric conditions, the child's blowing momentum is 65mNS, which translates to space conditions, and this 65mNS impulse can make quantum satellites run 50,000 kilometers. This experiment shows that in fact, a small force in space can allow a satellite weighing hundreds of kilograms to fly a long distance.
In fact, the thrust bench has made a great contribution to the ground engine of our national satellite, this platform has been applied in the ground experiment of the aerospace department, it is essentially a high-precision balance torsion system, its basic principle is to measure by converting the force into displacement, its force measurement range is about 1-1000mN, can do micro-force tests in the order of mN.
This bench is actually a very precise mechanical system, which can essentially detect very small displacements on a heavy bench, because this bench is very sensitive, and the movement of people around it will affect the stability of the bench. Then the scientists must add a damping system to the platform, so that the platform can quickly stop under working conditions in order to carry out the next experiment. If there is no damping on it, it can swing in the air for about half an hour before it can stop, but if the damping is added, it can stop in about a few seconds.
The role of microforce is huge, especially in the field of space exploration, it can make spacecraft and space stations dock together, running steadily in space, and it can also push Mars probes, or other aircraft to fly to other planets, to explore the unknown space.
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