How does gravity help keep satellites in orbit?

Gravity is the force that attracts objects with mass towards each other. In the case of satellites in orbit around the Earth, gravity is what keeps them in their circular or elliptical path around our planet.

To understand how gravity enables satellites to stay in orbit, it helps to know a bit about the mutual gravitational attraction between two objects. According to Newton's law of universal gravitation, the force of gravity between two objects depends on their masses and the distance between them.

In the case of a satellite orbiting the Earth, gravity is pulling the satellite towards the Earth's center while the satellite's velocity is causing it to move forward. These two forces, gravity pulling inwards and the satellite's velocity pushing outwards, result in a balance. This balance is what keeps the satellite in a stable orbit.

To calculate the speed and altitude required for a satellite to stay in orbit, scientists use the concept of centripetal force. They consider the gravitational force of the Earth pulling the satellite towards its center as the centripetal force required to keep the satellite in a circular orbit. This allows them to derive mathematical equations, such as Kepler's laws of planetary motion, which relate the satellite's mass, the Earth's mass, the orbital radius, and the necessary orbital velocity.

In practical terms, to achieve and maintain an orbit, satellites are launched with an initial velocity and placed in specific altitudes and velocities depending on their intended orbit type (e.g., low Earth orbit or geostationary orbit). This velocity, known as the orbital velocity, is carefully calculated to ensure that the gravitational pull of the Earth continuously pulls the satellite towards its center while the satellite moves at a tangential velocity to prevent it from falling back to the Earth or escaping into space.

In summary, gravity plays a crucial role in keeping satellites in orbit. The balance between the inward gravitational force and the satellite's outward velocity ensures that the satellite continues to revolve around the Earth without falling or drifting away.