Managing Cross Support With CCSDS Space Link Extension Services

Abstract

This paper outlines how Mission Managers may use the Space Link Extension (SLE) services that have been defined by Panel 3 of the Consultative Committee for Space Data Systems (CCSDS) to order and execute TTC Services for their spacecraft. The paper draws on the experience gained by VEGA in prototyping the SLE services in the QinetiQ ground segment in the UK. OVERVIEW The SLE Services provide a standard way of passing CCSDS telecommand and telemetry services across the ground segment. By implementing SLE services, TTC Services Providers will be able to provide a standard interface for supplying TTC services to Missions. This will reduce the cost of providing cross support services for spacecraft missions once the standard is in widespread use. In the near future, CCSDS tracking services and security will be added to the SLE capability, to facilitate the implementation of a fully operational SLE service. In the last year, VEGA has successfully tested the first implementation of SLE Service Management, controlling the online Forward Command Link Transmission Unit (F-CLTU) and Return All Frames (R-AF) services in the TTC ground segment operated by QinetiQ in the UK. Successive tests involved VEGA’s offices in Hertfordshire, England, QinetiQ’s control centre at Farnborough, England and QinetiQ’s ground station at West Freugh in Scotland. In the absence of an operational STRV spacecraft, the STRV engineering model was used in the tests. The VEGA implementation is a prototype of the services defined in the most recent issues of the CCSDS SLE Service Management recommendations, [2] to [4]. The experience gained in developing the prototype was fed back into the development of the recommendations so that both the prototype and the recommendations have a greater maturity than would otherwise be the case. The implementation uses web technology to enable spacecraft Mission Managers to check ground station availability, book passes and set up the data transfer services to be executed at the scheduled time. The service supports the complete life cycle from the initial service agreement to post pass reporting. The service management software in the ground station interacts with the ground station computer to configure the ground station resources and provide monitoring information to the user on the status of those resources during a particular pass. In the case of problems within the ground station, the service management software posts notifications that are accessible to the user via the web interface. The implementation includes both the data transport and service management layers of the SLE services and is therefore the first full prototype of these services. The paper assumes a basic level of knowledge of the SLE services, such as provided in [1]. This reference can be downloaded from the CCSDS web site at www.ccsds.org.