ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / Space Link Extension (SLE) is a set of recommended standards for mission cross support developed by the Consultative Committee for Space Data Systems (CCSDS). The SLE recommendations define protocols for extending the space link from ground terminals to other facilities deeper within a ground network, allowing distributed access to space link telecommand and telemetry services. The SLE protocols are widely used to provide cross support between sites, programs, and agencies. In traditional SLE deployments, individual service instances have been manually provisioned well in advance of the commencement of cross support for a particular mission, and hardware and software resources have been allocated to those service instances at the time of provisioning. While valid, this approach requires that dedicated resources be provided for each mission and service instance, and limits an SLE provider's ability to reallocate resources in real time based on system availability or other factors. This paper discusses an alternative approach to SLE service provisioning, in which individual service instances are assigned resources from a common resource pool at the time that each service instance is initialized. The paper addresses the key design elements and technical tradeoffs involved in this approach, and discusses the potential benefits with regard to load balancing, equipment reuse, and resiliency against system failure.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / Space Link Extension (SLE) is a set of recommended standards for mission cross support developed by the Consultative Committee for Space Data Systems (CCSDS). The SLE recommendations define protocols for extending the space link from ground terminals to other facilities deeper within a ground network, allowing distributed access to space link telecommand and telemetry services. The SLE protocols are widely used to provide cross support between sites, programs, and agencies. Traditional SLE protocol implementations have been limited in their ability to support high data rates and large numbers of concurrent service instances. Such limited solutions were sufficient to support the needs of spacecraft health and status or older, low-rate science data. More recent missions, however, have required significantly increased data rates on both uplink and downlink paths, necessitating a new approach to SLE implementation. This paper discusses the design principles involved in implementing the SLE protocols in support of high channel and aggregate mission data rates, with particular focus on the tradeoffs necessary to provide SLE link capability at sustained single-channel rates above 1 Gigabit per second. The paper addresses significant performance bottlenecks in the conventional SLE protocol stack and proposes potential mitigation strategies for them.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / CCSDS Space Link Extension (SLE) Services enable the ground segment assets of space agencies to interoperate, allowing for ground stations and space data users to interact without the need for ad hoc, complicated gateways designed specifically for each new mission. Their goal is to reduce the development, management, and operational costs of providing cross support between space organizations for exchange of tracking, telemetry, and command (TT&C) data. SLE services are actively supporting over a dozen spacecraft, with many more planned over the next few years. This paper first presents an overview of the underlying SLE architecture, as defined in the SLE Reference Model. The SLE data transfer services, which move data between mission facilities and ground stations are defined, along with the management services that enable missions to make requests for ground station services. Next, up-to-date status of the testing, prototyping, and implementation of SLE services over the past few years is presented, as well as plans for adoption of SLE services by a number of space networks and space mission organizations. Finally, efforts to adapt SLE services to support legacy missions are briefly described.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Consultative Committee for Space Data Systems (CCSDS) is developing standards for the interface through which spaceflight mission managers request tracking, telemetry, and command (TT&C) and Space Link Extension (SLE) services from TT&C ground stations and networks. The standards are intended for use not just by the spaceflight projects and networks operated by the CCSDS member agencies, but also by commercial networks and networks operated by other governmental agencies. As part of the process of developing the standards, several prototypes are under development. This paper presents a summary status of both the emerging service request standards and the prototypes that implement them.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A critical area for achieving interoperability between satellite control networks is the means chosen to interconnect Satellite Operations Centers and remote antenna systems. The CCSDS Space Link Extension (SLE) services are good candidates for this purpose, but national security space activities have demanding requirements for accuracy of data transfer, controlled delay, and security, which may not be fully achievable with the existing recommendations. The US Air Force developed a test bed to evaluate the SLE protocols during live satellite contacts, for both data transfer and management functions such as scheduling, configuring ground resources, and status reporting. Performance was generally satisfactory, but several extensions were found to be necessary. The SLE services provide a promising basis for use in ground stations to support both legacy Air Force interfaces and newer standards based satellite control services.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Space Link Extension (SLE) is a set of Consultative Committee for Space Data Systems (CCSDS) recommended standards for extending the space link from ground stations to other spaceflight mission ground facilities over a ground network, allowing distributed access to space link telecommand and telemetry services. The currently defined and implemented SLE recommendations are oriented around a traditional CCSDS telecommand and telemetry protocol set, which uses discrete telecommand frames that are encapsulated in Communication Link Transmission Units (CLTUs) for transport over the ground segment, and telemetry data encapsulated in Transfer Frames at the spacecraft. This paper discusses several non-traditional uses of the SLE services. The applications addressed within lie outside the discrete packet telecommand/telemetry subset of the SLE recommendations that are fully defined by CCSDS. This paper will focus on the use of the currently implemented SLE model to enable the transport of other forms of data, which may be subject to various transmission constraints, across the ground segment.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / NASA and Lockheed Martin-CSOC have been supporting in the development of plans for the evolution of NASA’s Ground Network (GN) and Space Network (SN), and where possible, synchronizing those plans with plans for the evolution of the Deep Space Network (DSN). This paper describes a recommendation for a common ground system communication architecture based on the Consultative Committee for Space Data Systems (CCSDS) Space Link Extension (SLE).