Explanation: The Iridium satellite communication system operates in Low Earth Orbit (LEO). LEO satellites, as their name suggests, orbit relatively close to the Earth, typically between 100 and 1200 miles altitude. The Iridium constellation specifically orbits at an altitude of approximately 485 miles (780 km). This lower altitude is chosen to minimize path loss and signal latency, allowing for smaller, less powerful handheld devices. However, because they are so close, LEO satellites move rapidly across the sky, necessitating a large constellation (like Iridium's 66 active satellites) to provide continuous global coverage. The other options represent different types of orbits: * 22,184 miles is the approximate altitude for Geostationary Earth Orbit (GEO) satellites, which appear fixed in the sky relative to the ground. * 11,492 miles and 4,686 miles fall within the range for Medium Earth Orbit (MEO) satellites, used by systems like GPS.