Consider a satellite orbiting the Earth in a stable circular orbit at a specific altitude. If an onboard thruster momentarily fires in the forward direction of motion, how does the orbital radius and total mechanical energy of the satellite subsequently change?

💡 Solution & Explanation

Firing a thruster forward applies a retro-thrust that slows down the satellite, reducing its orbital velocity and causing it to drop into a lower, higher-speed orbit with reduced total mechanical energy. Forward thrust in orbital mechanics acts as a brake because lowering velocity reduces centrifugal support relative to gravity at that instant. Mechanical energy in a bound orbit equals half the gravitational potential energy, which becomes more negative as the semi-major axis shrinks. Orbital maneuvers require careful vector calculations based on Keplerian laws.