Over the last two decades, deep space communication scenarios have evolved from simple point-to-point links between a spacecraft and Earth to more complex topologies, with data transfer over multiple hops via relay spacecraft and other intermediate nodes, involving users from various space agencies. ESA plays its role in this evolution with its current and planned Mars and Moon assets. This paper begins with the history of the European Relay Coordination Office (ERCO), which has been created to support the preparation and execution of communication via relay satellites between landed assets throughout the Solar System and their control centres on Earth. Such relay communication allows any compatible rover or other asset which does not have Direct-from-Earth (DFE) or Direct-to-Earth (DTE) communication capability to be monitored and controlled. It also increases return data volume even from users with such DFE/DTE communication. ERCO works with several orbiters at Mars and supports several current and planned assets on the Martian surface. It is also planned to be used to support lunar missions, building on the standardised interfaces and processes developed for relay communication with Mars. The paper explains the support provided by ERCO for a mission, which begins with analysis of the relay requirements, assessment of the communication scenarios, evaluation of the operations efficiency of the mission, and estimation of the relay data volumes. To do this, ERCO is supported by a comprehensive analysis tool, the Mars Relay Allocation Tool. The paper also gives a brief overview of the architecture of the ERCO data system, which provides common interfaces for lander control centres to plan and execute their relay communication sessions. Relay planning ranges from initial high-level planning of the complete mission (on a daily basis if required) through to detailed configuration of the orbiter communications equipment and the scheduling of individual relay sessions. For relay execution, the ERCO data system provides services to route commands from the lander control centres to the landers via a variety of orbiters, and conversely to bring telemetry from the lander back to the control centres. Automated processes and intensive planning ensure the minimum latency times between data from the lander being provided to the control centre, and vice-versa, taking into account visibility and availability of the releyant ground stations. The paper presents details of the work done to test the ERCO software, processes and procedures. This was achieved through a comprehensive system operational validation test performed between September 2019 and March 2020, involving fourteen operational control centres around the globe, including ESA, NASA and Russian lander control centres, deep space ground stations from three different ground station networks, and ESA and NASA relay planning and orbiter control centres. This global validation test allowed all the stakeholders to validate the various processes, procedures and systems used for relay communication planning and execution. The paper summarises the results achieved, identifies lessons learned and gives an overview of what is coming next as ERCO prepares for its operational roll-out to support relay services provided by ESA's Trace Gas Orbiter to NASA's Curiosity and Perseverance Rovers. It concludes with ideas of how ERCO could support future relay communication in other scenarios.
Getting the European Relay Coordination Office Ready for Business
2021-03-06
3839101 byte
Conference paper
Electronic Resource
English
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