The Evolution of Interface Specification for Spacecraft Command and Control

This paper describes an evolution from a traditional satellite commanding interface control document (ICD) to a service suite which provides real-time propagation and validation of interface changes. TEL handling, elucidation, modification, and investigation service (THEMIS) is the DigitalGlobe next-generation software suite which provides runtime validation of satellite tasking built by mission planning systems and spacecraft engineers. It enables more efficient management of multiple baselines and changes through the lifecycle of a constellation mission. Through THEMIS, developers, spacecraft engineers, and system engineers view, edit, and manage revisions of the spacecraft tasking interface. The interface specification is represented in JavaScript Object Notation (JSON) format and configuration management is provided through a GitHub repository. Once generated, the ICDs are used in real-time operations. This approach has reduced interface interpretation errors by having a single service able to validate commanding generated by multiple sources against any interface baseline.