Using CCSDS Standards for Space Situational Awareness

This paper discusses standards developed for the international space operations community by the Consultative Committee for Space Data Systems (CCSDS), with a focus on those standards applicable to Space Situational Awareness (SSA) and its objective of avoiding collisions among space objects. CCSDS is a multi-national organization that develops international communications and data systems standards for spaceflight; it is formally affiliated with the International Organization for Standardization (ISO). Within the CCSDS, a Navigation Working Group is chartered to produce recommendations related to the formatting and exchange of flight dynamics data. SSA relies on data of several sorts, including: observational data from tracking spacecraft and debris, estimated trajectories of spacecraft and debris, communicating analyses of close approaches/potential collisions to affected satellite operators, and communicating planned collision avoidance actions. Over the past several years, the CCSDS has published three international standards related to the data requirements of SSA that can be used together in a comprehensive, collaborative effort. The CCSDS Tracking Data Message (TDM), Orbit Data Messages (ODM), and Conjunction Data Message (CDM) standards can be used to exchange three SSA fundamental data types (tracking, trajectory, conjunction warnings). The CDM is the newest of these standards, just published in June 2013. Requirements for the CDM were developed collaboratively with the United States Air Force, multiple CCSDS member agencies, other space standards committees, and commercial interests. The CDM includes key data items such as the identification for two space objects (which could be either spacecraft or debris), Time of Closest Approach (TCA), miss distance, object states at TCA in standard reference frames, and covariance matrices of the two space objects at TCA. A fourth standard, the Spacecraft Maneuver Message (SMM) is currently very early in the CCSDS standards development process; it will be designed to facilitate information exchange related to spacecraft maneuvers and can be used to describe maneuvers that respond to conjunction warnings.