Physics – 6.1.2 The Solar System | e-Consult

A satellite in a low Earth orbit (LEO) requires a high initial velocity to maintain its orbit because it is constantly losing potential energy as it moves away from the Earth. This loss of potential energy is converted into kinetic energy, keeping the satellite in orbit.

The satellite's orbit is elliptical, although often approximated as circular for simplicity. When the satellite is closer to the Earth (lower altitude), it has a lower potential energy. When it is further away (higher altitude), it has a higher potential energy. The total energy (E = KE + PE) must remain constant due to the conservation of energy.

To maintain a stable orbit, the satellite must have sufficient kinetic energy to compensate for the loss of potential energy. If the satellite's initial velocity is too low, it will lose energy and spiral inwards towards the Earth. Conversely, if the initial velocity is too high, it will escape Earth's gravitational pull and move into space.

The initial velocity required is determined by the altitude of the orbit. Lower orbits require higher velocities because the potential energy loss is greater at lower altitudes. The required velocity is calculated based on the gravitational constant (G), the mass of the Earth (M), and the orbital radius (r). The formula for the velocity (v) in a circular orbit is: v = √(GM/r). For elliptical orbits, the velocity varies, but the average velocity is determined by the total energy and the semi-major axis of the ellipse.