The OPTIMUS Mission Planning System: Reactive Scheduling of Optical Ground Stations

Kurzfassung

Optical space-to-ground communication promises very high data rates and improved security compared to radiofrequency systems, but its widespread use is limited by scarce and heterogeneous Optical Ground Stations (OGS), strong weather dependence, and the need for reactive, probabilistic scheduling to ensure reliable link availability. In this context, the Optical Multi-User Service (OPTIMUS) is an ESA-funded testbed that implements an "OGS-as-aService" concept to federate distributed OGS networks through standardized interfaces, reactive planning, and Delay-Tolerant Networking (DTN) data delivery to enable resilient and interoperable optical ground segment operations. At the heart of OPTIMUS is the Mission Planning System (MPS) developed by DLR German Space Operations Center (GSOC), which orchestrates and reactively schedules optical links between spacecraft and distributed OGS resources.

The OPTIMUS MPS builds upon generic GSOC Mission Planning tools such as the Reactive Planning framework, the Plains planning library and the interactive PintaOnWeb user interface. Using a dedicated website (Human-Machine-Interface; HMI), a testbed operator may dynamically add or change configurations such as ground stations, DTN endpoints, spacecraft and orbits into the MPS backend through dedicated REST interfaces. Optical links can be requested by the user for any registered spacecraft; the OPTIMUS MPS dynamically calculates all suitable link opportunities during the given time interval, ranks them according to their expected quality (e.g. considering weather forecast and expected link budget), and selects the most promising link for execution. PintaOnWeb enables both the user and operator to monitor the scheduling process, to confirm or reject automatically selected links, or to select alternative opportunities as needed, e.g. when a ground station becomes unavailable on short notice. For ground stations operated by a service provider other than OPTIMUS itself, the pass booking process includes the exchange of scheduling information using the CCSDS Service Management standard.

Following the conclusion of the OPTIMUS development phase in the second quarter of 2026, the MPS architecture, its main interfaces and core functionalities are now presented in this paper. Furthermore, the results achieved are put into the context of the overall roadmap for generic optical link planning services at GSOC, and potential future extension stages of OPTIMUS will be outlined and discussed.