What is the difference between an artificial satellite and a geostationary satellite?

The main difference between them is: the objects on the earth's equator are subject to the gravitational force of the earth and the supporting force of the ground, and their resultant force provides the centripetal force, which is calculated as: centripetal force = gravitational force - supporting force, where the supporting force is equal to the gravitational force of the object, which is approximately equal to the gravitational force, so the centripetal force f1 is small and almost negligible.

Its centripetal acceleration a1 is also much less than g. The gravitational force of the artificial satellite is all used as a centripetal force, so the centripetal force f2 = gravitational force of the near-earth satellite is much greater than the centripetal force f1 on the equator (the gravitational force is the same in these two places), according to the centripetal force formula, it can be known that a2》a1,w2>w1,v2>v1, the linear velocity of the satellite in this orbit is equal to the first cosmic velocity. The geosynchronous satellite is located at a height above the ground about 6 times the radius of the earth, so the gravitational force is less than the first two, but it is all used as a centripetal force, and its angular velocity is the same as that of an object on the equator, and its f3>f1,a3> a1,v3>v1 can be known from the centripetal force formula.

As for near-Earth satellites and geostationary satellites, since their gravitational force is used to do centripetal force, and geostationary satellites are far from the ground and have small gravitational force, so f2》f3,a2>a3,The farther the satellite is from the ground, the smaller the linear velocity and angular velocity, so v2》v3,w2》w3.

What we generally call geostationary satellites is just one type of artificial satellite.

When conducting scientific expeditions at the South Pole or the North Pole, communication satellites can be used to communicate with regions beyond the poles through the communication satellites of geostationary satellites.

In satellite communications, geostationary satellites are the most widely used, and the main reasons are:

First, geostationary satellites are up to 35,800 km above the ground, and the coverage area of a satellite (the area of the earth that can be "seen" from the satellite) can reach about 40% of the total area of the earth, and the maximum span of the ground can reach 18,000 km. Thus, with only three satellites properly configured, global communications can be established beyond the polar regions (Antarctic and Arctic).

Second, because geostationary satellites are stationary relative to the Earth, the ground station antenna is easy to keep aligned with the satellite and does not require a complex tracking system; The communication is continuous, unlike when the satellite is moving at a certain speed relative to the earth, and the signal needs to be changed to the satellite at that time and the signal is interrupted; The signal frequency is stable and does not produce Doppler shifts due to the motion of the satellite relative to the Earth. Of course, geostationary satellites also have some shortcomings, mainly in the following aspects: the polar region is a communication blind spot; The satellite is far away from the earth, so the transmission loss and transmission delay are large. There is only one geosynchronous orbit, and the number of satellites that can accommodate it is limited; The launch of geostationary satellites and the tracking and control technology in orbit are complex.

In addition, around the spring and autumn equinoxes, there are also star eclipses (satellites entering the shadow area of the Earth) and solar transit interruptions (satellites are between the Sun and the Earth, and communication is interrupted due to strong solar noise).

Geostationary satellites are synchronized with the Earth's rotation period, i.e. the period is 24 hours.

Objects on the equator are not nucleus, they are placed on the ground, such as a stone placed on the ground, a person standing on the ground, the period is synchronized with the earth, for 24 hours. Note that an object at the equator is a little different from a satellite, the satellite is the gravitational force that completely provides the centripetal force, while the object on the equator has a small centripetal acceleration and the difference between the gravitational and support forces provides the centripetal force.

Near-Earth satellites are satellites orbiting the air near the ground and operating at the first cosmic velocity.

These three are more auspicious than the land

In terms of period, objects on the equator are the same as geostationary satellites, both are larger than near-Earth satellites, and the period calculation of near-Earth satellites.

gmm r 2 = m(2 t) 2 r, t can be calculated or the equatorial circumference divided by the first cosmic velocity, which is roughly calculated to be between 5000 and 5100 seconds, much less than 24 hours.

In terms of velocity, you can use gmm r 2 = mv 2 r, and we can get that v 2r = gm is a constant, that is, the larger the orbital radius of the satellite, the smaller the linear velocity. The linear velocity of the object on the surface of the equator is brought by the rotation of the earth, and it is not in the same system as the satellite, which is about 463 meters and seconds, so the linear velocity of the satellite is not necessarily related to the autobiographical speed of the earth. But it is very easy to compare geostationary satellites with the rotation of the earth, they have the same angular velocity, and the radius of geostationary satellites is larger than that of the earth, so the linear velocity is large.

The acceleration, which is the largest for near-Earth satellites, is approximately equal to g, and gradually decreases as the radius increases, calculated using gm r 2.

Objects on the equator, accelerometers and satellites are also not part of the same system, but are a constant, which is the angular velocity of the Earth's rotation * the radius of the Earth.

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A geostationary satellite is an artificial Earth satellite with the same period of operation and rotation as the Earth, which remains relatively stationary with the Earth and is always located directly above the equator.

Near-Earth satellites (NEOS) are satellites whose orbits are near the Earth's surface, and the orbital radius can be approximated when calculating.

1. Similarities between geostationary satellites and near-Earth satellites.

1.Both are moving in a uniform circular motion around the Earth's axis, and the centripetal force is related to the Earth's gravitational pull;

2.Geostationary satellites have the same period as objects on the equator: t = 24 h;

3.Near-Earth satellites have the same orbital radius as objects at the equator: r=r0 (r0 is the radius of the Earth).

2. Differences between geostationary satellites and near-Earth satellites.

1.The orbital radius of the synchronous satellite is different: the orbital radius of the synchronous satellite = r0 + h, h is the height of the synchronous satellite from the ground, about 36,000 kilometers, and the orbital radius of the near-earth satellite and the equatorial object is approximately the same, both are r0.

2.The centripetal force is different: the centripetal force of geostationary satellites and near-Earth satellites orbiting the Earth is provided entirely by the Earth's gravitational pull towards them, the centripetal force of an equatorial object is provided by one component of gravity, and the other component of gravitational force provides the gravitational force of an equatorial object.

3.The centripetal acceleration wheel combustion search degree is different.

4.The cycle is different.

5.The line speed is different.

6.The angular velocity is different.

Characteristics of near-Earth satellites: Ideally, satellites that are close to the Earth's surface, with a radius of rotation equal to the Earth's radius.

Characteristics of artificial satellites: the launch speed is not necessarily, it may be a near-earth satellite, it may be a synchronous satellite, it may be a satellite of another planet. Depends on the launch speed.

Characteristics of geostationary satellites: From outside the earth, the satellite rotates together with the earth, and the angular velocity is the same as the angular velocity of the earth's rotation. Remain relatively stationary with the Earth (in the same direction, at equal velocity).

The relationship between the three: Near-Earth satellites and geostationary satellites are both types of artificial satellites. There can be many kinds of artificial satellites, and if the launch speed is appropriate, they can become near-Earth satellites or geostationary satellites, and of course they can also become other types of satellites.

1. The cycle is different.

A period of 85 minutes for near-Earth satellites and 24 hours for geostationary satellites.

2. The relative speed is different.

Near-Earth satellites are moving relative to people on the ground, and geostationary satellites are synchronous and stationary relative to the ground.

3. The height is different.

The operating altitude of the near-Earth satellite is equivalent to the radius of the earth, and the geostationary satellite is operating at an altitude of 35,786 kilometers.

1. The track radius is different

1) The orbital radius of the geostationary satellite = r0+h, h is the height of the geostationary satellite from the ground, which is about 36,000 kilometers.

2) Near-Earth satellites have approximately the same orbital radius as equatorial objects, both r0.

2. The centripetal force is different

1) The centripetal force of geostationary satellites and near-Earth satellites orbiting the Earth is provided entirely by the Earth's gravitational force towards them, the centripetal force of an equatorial object is provided by one component of the gravitational force, and the other component of the gravitational force provides the rebound force of the equatorial object.

3. The height is different.

1) The operating altitude of the near-Earth satellite is equivalent to the radius of the Earth.

2) The altitude of the geostationary satellite movement is 35,786 km.

4. The operating cycle of the satellite is different

1) Near-Earth satellite: Near-Earth satellite's geostationary satellite = object on the equator, which is t = 85min.

2) Geostationary satellites: Geostationary satellites have the same period as planetary rotation. The period of near-Earth satellite operation is t=85min, which is the minimum period of all satellites.

Encyclopedia - Geostationary satellites.