Rocket propulsion basics

Astronomical Unit - It is a measure of distance equals the mean distance between earth and sun (150x10^6 km)

Escape Velocity - Velocity required for a body to escape the attractive force of the planet/star. (for more details click the highlighted heading)

Frame of reference : Reference based on which the position of the body is described.

Force : Rate of change in momentum

Free fall : Body moving freely under the influence of the gravitational field , An observer in a freely falling body is in a state of weightlessness,It can be either Orbital or Sub orbital flight

Geo-Synchronous Orbit : Orbit having an angular velocity equal to the angular velocity of the planet around which orbit takes place.(for more details click the highlighted heading)

Geo-Stationary Orbit (Clarke orbit) : An orbit in the equatorial plane of the reference planet or celestial body such that the orbiting body appears to be fixed point for any observer on the reference planet or celestial body. (for more details click the highlighted heading)

Gravitational constant G : The constant in the universal law of gravitational force giving the attractive force between two masses separated by a given distance.when the mass is expressed in 'kg' and the distance in 'm' , the gravitational constant is 6.670 x 10^-11 Nm2/Kg2

Gravitational field : Force of attraction on a mass 'm' kg in a gravitational field 'g' is m x g N , Unit of gravitational field is m/s2

Impulse : change of Momentum.

Inclination : Angle between orbital plane and equatorial plane of the planet.

Inertial frame of Reference : A frame of reference that is absolutely stationary or moves at constant velocity

Kepler's Laws : laws describing the motion of planets in the solar system.
1.Law of Ellipses
2.Law of equal areas
3.Law of harmonies
(for more details click the highlighted heading)

Molniya Orbit : Highly Elliptic orbit about the earth with large eccentricity and an apogee of about 400,000 km in the northern hemisphere.

Momentum : Product of mass of a body and its velocity

Orbit : Trajectory or path of motion in space ; path in which a planet ,satellite or spaceship moves

Orbital velocity : Velocity along the path of the orbit

Polar orbit : Orbit having an inclination of 90 degrees

Pseudo-force : Fictitious force in a non-inertial frame of reference of correctly describe the motion of the body in the non-inertial frame of reference .In a rotational frame of reference ,the pseudo force is a centrifugal force

Sun Synchronous orbit : A polar orbit in which angle between the line joining sun with Earth and the orbital plane remains constant

Geo Stationary Orbit

If the plane of the Geo Synchronous orbit is in the equatorial plane of the Earth and the body in that orbit rotates in the same direction as the Earth Rotates, then that orbiting body will always appear to be stationary to an observer standing on Earth's surface.It is then said to be Geo stationary orbit. this orbit is a particular type of Geo Synchronous orbit.

the concept of Geo Synchronous and Geo stationary not only applicable for Earth but also applicable for Every other planet in the galaxy and Natural satellites as long as they are rotating about an axis.

It is considered to be a circular orbit at a distance of about 35,786km from Earth surface.

This orbit is very much useful for
communication satellites,
broadcast satellites,
SBAS satellites (Satellite Based Augmentation System )
GNSS satellites (Global Navigation Satellite System) etc.,

Arthur Clarke , Author of several Science fiction books , had put forward this concept in 1945 , hence this referred to "Clarke's Orbit"

The first satellite to be placed in the Geo-Stationary orbit was Syncom-2 on July 26th 1963.