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Optical satellite communications play an increasingly important role in a number of space applications. However, if the system concept includes optical links to the surface of the Earth, the limited availability due to clouds and other atmospheric impacts need to be considered to give a reliable estimate of the system performance. An OGS network is required for increasing the availability to acceptable figures. In order to realistically estimate the performance and achievable throughput in various scenarios, a simulation tool has been developed under ESA contract.

The DTN-EO study was initiated in order to research the performance of DTN in future missions, particularly Earth Observation and constellation-type missions. In the original proposal, ESA stipulated 3 scenarios which were to be tested: Earth Observation, Constellation, and Exploration missions. These scenarios built from each other, starting with an Earth-Observation centric mission such as the Sentinel missions, before moving to a large constellation. Ultimately, the DTN network from the first two scenarios was expanded to represent a deep-space exploration mission.

The purpose of this study is the definition of a communication subsystem architecture (including both ground and space segments, as well as operational methods) that allows robust RF TT&C links during superior solar conjunction phases. The defined architecture shall ensure robust and reliable links in scintillation regimes (i.e. at low SEP angles) where TT&C links are nowadays degraded, leading to occasional link interruptions. Similarly, the defined architecture shall ensure that at even higher scintillation regimes (i.e.

While the MEOSAR is moving to FOC with Galileo satellites that are equipped with SAR transparent payloads, ESA is already investigating its future Galileo-2 (G2G) system for new features. In this framework, one of the aims of the ESA study on Future Concepts for Galileo Search And Rescue was to define a preliminary design of a new SAR payload capable of processing both First Generation Beacon (FGB) and future Second Generation Beacon (SGB) signals.