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Good morningeveryone, my name is ZhouJianshuo.Today，my topic is Slingshot effect,physics in Astronomy.Slingshot effect, in Chinese we call it “引力弹弓效应”，is an astronomicaltechnology used in the field of the interstellar travel,in Chinese means “星际航行”

The origin of Slingshot effect dates back to the early 1920s, when a famous soviet scientist called 尤里·康德拉图克,first came up with this idea.In short, it works like this.Suppose that you want to arrive at an extremely remote location in space，here，we call it location A（画上），because it is so far from you that you cannot head to it in normal way，or you will die before you reach it.All you need is a big planet，which is located in the location B（画上）Then you need to make your aircraft move in the specific orbit, like this.(画一半)This orbit and the speed must be very accurate in order to accelerate the aircraft by the gravity of the planet with the least time and fuel.Then the aircraft will move like this(画上), reaching the destination with a very fast speed.That is the slingshot effect.The physical theory of the slingshot effect is the conservation of momentum, in Chinese called “动量守恒”。The schematic is like this.A “stationary” observer sees a planet moving left at speed U and a spacecraft moving right at speed v.If the spacecraft has the proper trajectory, it will pa close to the planet, moving at speed U + v relative to the planet's surface.When the spacecraft leaves orbit, it is moving at speed U + v relative to the planet's surface but in the opposite direction.Since the planet is moving left at speed U, the total velocity of the spacecraft relative to the observer will be the velocity of the moving planet plus the velocity of the spacecraftwith respect to the planet.So the velocity will be 2U + v Slingshot effect is frequently used in astronomy.For example, In 1974,The Mariner 10 probe was the first spacecraft to use the gravitational slingshot effect to reach another planet, on its way to becoming the first spacecraft to explore Mercury.No one can conceal the fact that slingshot effect exerts a tremendous influence on the current astronomical research.And the technologies which use the basic physical theory play an eential part in Science.That is the end of my presentation,Thank you very much.