The Near Spacecraft Telecommunications System

The Near Earth Asteroid Rendezvous (NEAR) mission, first in NASA's Discovery series, is designed to gather scientific data about the near-Earth asteroid 433 Eros. Due to launch in February 1996, the spacecraft will rendezvous with and eventually orbit the asteroid. The telecommunications system is centered about two redundant X-band transponder systems that provide the command, telemetry, and tracking functions. Although the mission has a very tight development schedule, a significant amount of new technology has been used in the telecommunications system. Included in the design are the most recent developments in transponder hardware, an X-band solid state power amplifier (a deep space "first"), and several microstrip patch antennas. During spacecraft emergencies, a microstrip array antenna becomes an integral part of a unique acquisition algorithm used to find the earth, similar to a search radar concept. To complement the flight hardware development, a comprehensive set of RF ground support equipment (RF GSE) has been developed. Also discussed are areas for potential technology improvements for future missions.