The NEAR command and data handling system

The Near Earth Asteroid Rendezvous (NEAR) spacecraft's command and data handling (C&DH) system is designed to manage complex operations and to collect data when the spacecraft is out of contact with ground control. During ground contacts, the C&DH system accepts uplink commands and memory loads that describe a time-ordered set of events to follow, and it transmits previously recorded data back to the ground station. This article describes the overall C&DH system, gives details on each of the components, and tells how the system was tested prior to spacecraft integration. Solid-state data recorders and flight computers are also discussed. (Author)