Commanding Via the CCSDS Forward CLTU Service: The Mission Perspective

The Forward CLTU Service, a component of CCSDS's Space Link Extension, represents a substantial cost savings, mitigates risk, and minimizes ground system development and integration time. This exciting breakthrough enables a consistent interface, independent of the ground hardware and antenna performing the actual uplink. Thus, this standard protocol promotes interoperability between organizations, expanding the number of heterogeneous uplink assets available to a mission. In addition, mission operators can become familiar with one protocol, decoupled from any mission-specific commanding requirements. The COmet Nucleus TOUR (CONTOUR) was the first externally operated NASA mission to incorporate the SLE Forward CLTU Service into its mission operations. Launched in July 2002, CONTOUR is operated from its Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD, using the Deep Space Mission System. CONTOUR was the first mission to utilize the SLE Forward CLTU Service for launch and early operations. The integration of the SLE Forward CLTU Service is 100% reusable on future missions. Subsequent missions managed by JHU/APL, including MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER), Solar-TErrestrial RElations Observatory (STEREO), and New Horizons, will utilize this service, unchanged. This paper describes the lessons learned from the rapid integration of this new standard into an existing ground system. SPACE LINK EXTENSION In the early 1980's, the Consultative Committee for Space Data Systems (CCSDS) was formed by the major space agencies of the world to address the common problems in the development and operations of space data systems. Their goal was to reduce the cost of future space missions, enable cross support, and improve the understanding and ensure the preservation of space related data. Since established, CCSDS has developed recommendations for data and information standards. Focusing initially on ground to space element communications, their Space Link Recommendations have enjoyed widespread adoption by flight and ground system designers.