What is the FCC Part 97 definition of a space station?

Question

Accepted Answer

The correct answer is C: An amateur station located more than 50 km above Earth's surface. This precise definition is found in FCC Part 97.3(a)(41). The 50-kilometer threshold distinguishes space stations from terrestrial amateur stations and is based on the internationally recognized boundary of space.

The 50 km (approximately 31 miles) altitude is significant because it represents the point where atmospheric effects on radio propagation change dramatically. Above this altitude, stations operate in what is essentially space, where different propagation characteristics apply. This definition covers amateur satellites, high-altitude balloons (if they exceed 50 km), and any other amateur station operating above this altitude. The definition focuses on altitude, not whether the station is manned or what it's used for - any amateur station above 50 km is a space station by definition.