NASA Standard Communications and Data Handling Subsystem

Abstract

At the 1975 International Telemetering Conference Charles F. Trevathan discussed the Multimission Modular Spacecraft (MMS) in general and the Communications and Data Handling (C&DH) subsystem in particular. The National Aeronautics and Space Administration's Goddard Space Flight Center (NASA GSFC) Is managing the MMS program and is integrating the first spacecraft, the Solar Maximum Mission, in-house. Contracts have been let for the Modular Power Subsystem (MPS), Attitude Control Subsystem (ACS) and the Communications and Data Handling (C&DH) Subsystem. The C&DH subsystem provides the command and telemetry link between the spacecraft and the terrestrial system; distributes commands to and collects telemetry from all spacecraft systems via a duplex serial multiplex data bus and Remote Interface Units (RIU's); and contains on board computation capability. The C&DH is a single 4 x 4 x 1- 1/2 foot module. The staffed module weighs 270 pounds including 60 pounds of mission unique equipment. The future for this kind of versatile hardware is exceptionally bright as it is cost effective and its modular structure permits repair, refurbishment and even modification/dating in space.