Elliptic orbit is a kind of universal existence;according toNewton's law of motion, F=ma, that is, under the action of external force, the object will produce an acceleration in the direction of force. According to the law of universal gravitation, any object with mass will attract each other. The magnitude of the attraction depends on the mass of the two objects and the distance between them F=GM1M2/R2.So, for example, the earth's movement direction has a deviation speed from the sun. If there is no gravity, the earth will gradually move away from the sun in the universeUniform linear motion；And just because the gravity makes the earth have an acceleration in the direction of the sun, the earth will shift in the direction of the sun and constantly change the speed and direction, making the earth rotate around the sun;In general, when an object is close to another object, it is gradually captured and the attraction is gradually increased. Therefore, the closer the object is to the attraction, the greater the acceleration and speed are. The greater the speed is, the more difficult it is to change the motion of the object (f=mv ^ 2/r). Therefore, unless the absolute balance is reached, it will not basically become a standard circular motion;As for the elliptical orbit, the elliptic equation can be deduced according to the speed and distance of motion.[1]
Law of motion
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The elliptical orbit has two focal points, and the central star is located on one of them. For example, the orbit of the earth around the sun is elliptical, and the sun is located on one of the focal points of the ellipseKepler's three laws：
1. AllplanetThe orbit around the sun is elliptical, and the sun is at a focus of the ellipse;
2. The radial path of the planet sweeps the same area in the same time.
3. The ratio of the third power of the semi major axis of all planetary orbits to the second power of the orbital period is equal.
Sports characteristics
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Generally speaking, satellite orbits are not circles but ellipses.A circle is a collection of equal distances from each point to a given point, which is the center of the circle.Instead of this center (or center), an ellipse has two focal points.An ellipse is a collection of points whose total distance to these two focal points is constant.Therefore, a circle is a special case where two focal points are merged into a single point.In fact, the Earth is always at the focus of an elliptical satellite orbit.
The line passing through the longer part of the two focuses of the ellipse is called the major axis, and the line passing through the shorter part of the two focuses of the ellipse and perpendicular to the major axis is called the minor axis.
The deviation of ellipse from circle is described by eccentricity.The point on the elliptical orbit where the satellite is closest to the earth is called perigee, and the point on the elliptical orbit where the satellite is farthest from the orbit is called apogee.Perigee and apogee lie at two vertices of the long axis.
Satellites in elliptical orbits move faster when they are close to the Earth (near perigee) and slower when they are far from the Earth (near apogee).The speed of a satellite at a given point depends not only on its height but also on the shape of its orbit (especially the length of its major axis).For a satellite in an elliptical orbit, its speed at a given altitude can be either greater than that of a circular orbit satellite at the same altitude or smaller than that of a circular orbit satellite at the same altitude, depending on the shape of the ellipse.
The orbital period also depends on the length of the major axis. As the length of the major axis increases, the orbital period also increases.The elliptical orbit can be a geosynchronous orbit, but because the orbital speed of the satellite changes with time, it is not really geosynchronous.[2]
Movement speed
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Let the distance between the gravity centers of two objects in the initial state be r1, and the distance between the gravity centers of two objects in the final state be r2;
The mass of the earth is M, and the mass of the satellite is m;According to the conservation of mechanical energy, when the distance is r1, r2, the satellite speed is V1, V2 andKepler's second lawThen V1r1=V2r2.
High elliptical orbit is a kind ofPerigeeAnd very highApogeeWith apogee height greater thanGeostationary satelliteThe height of (36000 km).according toKepler's lawThe satellite runs slowly in the area near the apogee, so this extremely elongated orbit is characterized by a very long process for the satellite to reach and leave the apogee, and a very short process for passing the perigee.This allows the satellite to cover the ground area below the apogee for more than 12 hours.This feature can beCommunication satelliteUsed.
High elliptical orbit satellites with large tilt angle can cover the earth'spolar regionRegion, which is operated onGeosynchronous orbitThe satellite can't do it.Since most of the territory of the Soviet Union (and now Russia) is located in higher latitudesGeosynchronous satelliteIt is of little significance, so the Soviet Union is the country that attaches the most importance to the development of high elliptical orbit satellites.A famous type of high elliptical orbits, namelyLightning track(or transliterated asMonya orbit，dip angle63.4 °)Carrier rocketName（flits ）Named.
