Dissection of the CCSDS Space Link Extension (SLE) Transfer Services
Juan Fernando Vizcaya Garcia, Erik Soerensen, Daniel Firre, Fabienne Delhaise · SpaceOps 2014 Conference · 2014
The CCSDS cross-support Space Link Extension (SLE) services standards have been adopted by the main space organizations during the last decade. This has created a global system of interoperability and currently, spacecrafts are supported by multiple space agencies providing telemetry to the ground and receiving telecommands from the Mission Control Centre via different SLE compliant ground segment systems (Mission Control systems, TM&TC providers, SLE gateways, etc.) belonging to different space organizations (e.g. ESA, NASA, CNES, DLR, ASI, JAXA, CNSA, INPE, ISRO, etc.). To ensure a correct inter-agency operability among these SLE systems, the execution of coordinated crosssupport SLE tests between the different space organizations is required. Sometimes, these tests are not successful due to misalignments in the SLE systems’ configurations, network anomalies and other unforeseen issues (e.g. software bugs), resulting in extra analysis and troubleshooting activities to be performed by the space agencies involved in the tests. These investigations can take a long time, since the SLE ground segment systems used by the different space agencies do not always provide meaningful SLE traces and logging capabilities. To overcome these issues, the European Space Operation Centre (ESOC) has developed a real-time CCSDS Space Link Extension (SLE) dissector based on the popular open source network sniffer “Wireshark”, that is able to detect, decode and dissect the SLE Protocol Data Units (PDU) that are exchanged via the return and forward SLE transfer services between two or more SLE compliant systems. This paper describes the motivation for creating the SLE dissector and it presents the benefits of using the SLE dissector for inter-agency cross-support operations with a practical example (SLE cross support tests between NASA and ESA for the provision of MAVEN telemetry to NASA’s Mission Control Centre via the ESTRACK’s SLE TM&TC providers located at ESA’s ground station in Perth). Finally, this paper proposes possible future applications of the SLE dissector in the field of operations and engineering.