THE NEW STANDARD SPACECRAFT TIMECODE

Abstract

In an effort to reduce the costs of conducting space missions, the National Aeronautics and Space Administration (NASA) is working to develop data systems standards that are appropriate for application at key interfaces within mission data systems. Use of proper standards can improve multimission support by reducing the need for developing new interfaces and data transforms for each new mission. “Time” is an important parameter for space-acquired measurements because instrument analysis can often be based on a sampled sensor time series and because time provides the most efficient (and often the only possible) linkage between instrument data and externally generated ancillary parameters. Therefore, one of the major aims of the NASA effort has been focused on the development of a standard timecode structure. This paper describes the rationale and form for that structure and provides a proposed definition for an important class of timecodes, the binary unsegmented codes. The structure provides a mechanism for the self-documentation of timecodes, so that any user of the data can interpret time measurements in an unambiguous manner. The binary unsegmented codes are modular and easily machine-readable, and feature expandable resolution and ambiguity periods.