Question

Почему спутники обращаясь вокруг земли под действием силы тяжести не падают на землю

Answer 1

Спутники находятся в процессе падения, но падают не на землю, а вокруг нее.

Спутнику сообщают энергию необходимую для преодоления гравитации Земли.  Не будем вдаваться в подробности как это делаю (с помощью ракеты, и спутнику нужно сообщить так называемую первую космическую скорость). Но спутник двигается параллельно Земле, силы гравитации тянут спутник обратно на Землю, но его поступательная скорость уравновешивает силу притяжения  и спутник начинает вращаться по орбите.

Answer 2

Why don't satellites fall to Earth due to gravity?

Satellites orbiting the Earth do not fall to the ground due to the balance between their forward motion and the force of gravity pulling them towards the Earth. This balance allows them to remain in a stable orbit around the Earth. Let's explore this in more detail.

The concept of orbital motion

To understand why satellites stay in orbit, we need to consider the concept of orbital motion. When an object is in orbit around a larger celestial body, such as the Earth, it is constantly falling towards the Earth due to gravity. However, it also has enough forward velocity to keep missing the Earth and fall in a curved path around it.

Balance between gravity and forward velocity

The key to a satellite's stable orbit is the balance between the force of gravity pulling it towards the Earth and its forward velocity. The satellite's forward velocity is carefully calculated and adjusted to ensure that it matches the curvature of the Earth's surface. This allows the satellite to continuously fall towards the Earth but never actually reach the ground.

Achieving and maintaining orbit

To achieve and maintain orbit, satellites are launched into space with sufficient initial velocity. This velocity is typically achieved by powerful rockets during the launch phase. Once in space, the satellite's onboard propulsion system or gravity-assist maneuvers can be used to fine-tune its orbit.

Different types of orbits

Satellites can be placed in different types of orbits depending on their intended purpose. Some common types of orbits include:

1. Low Earth Orbit (LEO): Satellites in LEO are relatively close to the Earth's surface, typically at altitudes ranging from a few hundred kilometers to around 2,000 kilometers. Examples of satellites in LEO include the International Space Station (ISS) and many Earth observation satellites.

2. Geostationary Orbit (GEO): Satellites in GEO are positioned at an altitude of approximately 36,000 kilometers above the Earth's equator. They orbit the Earth at the same rate as the Earth's rotation, allowing them to remain fixed relative to a specific location on the ground. GEO satellites are commonly used for telecommunications and weather monitoring.

3. Polar Orbit: Satellites in polar orbits pass over the Earth's poles during each orbit. These orbits are often used by Earth observation satellites to provide global coverage.

Conclusion

In summary, satellites do not fall to the ground due to the balance between their forward velocity and the force of gravity. This balance allows them to remain in a stable orbit around the Earth. The specific type of orbit and the satellite's initial velocity determine its altitude and path around the Earth.