how satellite stay in orbits without fuel
Satellites stay in orbit without continuously expending fuel because of the balance between their orbital velocity and the gravitational force of the planet they are orbiting. This state of balance is known as "free fall," and it allows satellites to remain in a stable orbit for extended periods of time.
Here's how it works:
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Orbital Velocity: When a satellite is launched into space, it is given a specific velocity called orbital velocity. This velocity is carefully calculated based on the altitude of the desired orbit and the mass of the planet. Orbital velocity is the speed at which a satellite must travel to maintain a circular orbit at a specific altitude above the planet's surface.
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Gravitational Force: Satellites in orbit are under the influence of the planet's gravitational force, which pulls them toward the center of the planet. However, because they have been launched with enough velocity, the curvature of their path matches the curvature of the planet. This causes the satellite to continuously fall toward the planet but also to move horizontally at such a speed that it keeps missing the planet's surface.
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Constant Free Fall: The satellite is in a state of constant free fall due to the balance between its forward motion and the gravitational pull. This continuous falling motion creates a curved path around the planet, which we perceive as an orbit.
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Zero Air Resistance: In space, there is very little air resistance or atmospheric drag to slow the satellite down. This lack of significant resistance allows the satellite to maintain its orbital velocity and trajectory for a long time.
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Conservation of Momentum: According to Newton's laws of motion, objects in motion tend to stay in motion unless acted upon by an external force. In the vacuum of space, the satellite's momentum keeps it moving in its orbital path.
While satellites don't require fuel to maintain their orbits, they might need occasional adjustments to counteract the effects of atmospheric drag, gravitational perturbations from the Moon and the Sun, and other factors that can cause their orbits to decay over time. These adjustments are typically made using onboard thrusters or other propulsion systems. However, these maneuvers are infrequent and use a relatively small amount of the satellite's total fuel supply.