Motion of Artificial Satellites

Artificial satellites are objects launched into space to orbit the Earth for various purposes such as communication, navigation, remote sensing, and scientific research. Their motion is governed primarily by the Earth's gravity and the laws of physics.

Key Points about Satellite Motion:

  • Orbit: A satellite's orbit is the path it follows around the Earth. It can be circular, elliptical, or even parabolic or hyperbolic.

  • Kepler's Laws: The motion of satellites is described by Kepler's Laws of Planetary Motion:

    • First Law: The orbit of a satellite is an ellipse with the Earth at one focus.

    • Second Law: A satellite sweeps out equal areas in equal times. This means it moves faster when it is closer to the Earth and slower when it is farther away.

    • Third Law: The square of the orbital period of a satellite is proportional to the cube of its average distance from the Earth.

  • Orbital Velocity: The speed at which a satellite orbits the Earth depends on its altitude. Satellites in lower orbits need to move faster to counteract the stronger gravitational pull.

  • Orbital Inclination: The inclination of an orbit is the angle between the orbital plane and the Earth's equatorial plane. A satellite with an inclination of 0 degrees orbits directly above the equator, while a satellite with an inclination of 90 degrees orbits over the poles.

  • Orbital Period: The time it takes for a satellite to complete one orbit around the Earth is called its orbital period. It depends on the satellite's altitude.

  • Geostationary Orbit: A geostationary orbit is a special type of orbit where a satellite appears to be stationary in the sky from the Earth's surface. This is achieved by placing the satellite at an altitude of approximately 35,786 kilometers above the equator.

  • Polar Orbit: A polar orbit is an orbit that passes over the Earth's poles. This type of orbit is useful for satellites that need to survey the entire planet, such as weather satellites.