Retrograde Orbit

A retrograde orbit is any orbit with an inclination greater than 90°, resulting in the satellite orbiting in the opposite direction to Earth's rotation (westward). Most satellites use prograde orbits (inclination < 90°) because launching eastward exploits Earth's rotational velocity (460 m/s at the equator). Launching into a retrograde orbit requires overcoming this velocity bonus, costing additional delta-v. Sun-synchronous orbits are technically slightly retrograde (97–98°). Israel launches retrograde over the Mediterranean to avoid overflying hostile territory to the east.