GSOC Flight Dynamics Microservices for Satellite Operations Support

Abstract

Exchanging information in a smooth and reliable manner is an essential component in spacecraft operations. For this, the Flight Dynamics department at the German Space Operations Center of DLR steps aside from the popular data-driven approach for exchanging products. Incorporating the philosophy to do one thing and to do it well, Flight Dynamics is establishing microservices based on the service-oriented architecture to provide Flight Dynamics core functionalities to specific users via network services. This approach translates into a high level of modularity and high flexibility in deployment. In addition, the products are decentralised and scalable to the customer’s needs, which includes independent communication irrespective of the programming language. These microservices provide customers with tailored products in a fast way, while reducing the amount of transferred data. Operating using the microservices results in an increase of repeatability, and provide the ability to monitor requests for traceability. To provide data products on request, the microservices connect Fortran with Python using F2x, a versatile, template-based Fortran wrapper written in Python. In this way, the high-level Flight Dynamics core libraries are kept in Fortran, which is a powerful, efficient and fast language. While maintaining heritage, a modern language as Python enables the required flexibility with modern interfaces to enable the web service. Combining best of both languages, the microservices can serve different clients for different tasks with no compromise at performance. Besides connecting Fortran and Python, there are other challenges that the microservices platform handles, related to maintainability of the source code, the use of common databases and transparency throughout the services. Containerisation allows to overcome these challenges by deploying the services based on Docker, to provide a platform as a service. The capsuled source code in Docker enables transparent logging while obtaining a highly-scalable platform when operated in an appropriate framework. At Flight Dynamics, the service-oriented architecture is applied to support small and compact tasks. The microservices, which are rapidly increasing, thus provide on-demand, real-time services to the customer over network. Among the existing microservices, there is a microservice for spacecraft orbit and ground track analyses and one for determining the attitude guidance profile for the EnMAP Earth observation mission. Recent developments are focused on (optical) communication. A microservice is developed for mission operations and mission planning where the ground stations can request orbit-related event information, such as eclipses or ground station visibility opportunities, based on different types of orbit data: a Two-Line Element, Orbit Ephemeris Message or Consolidated Prediction File. Another development is a generic planning tool for optical communication, based on software developed for the support of laser-communication terminal (LCT) operations in GEO, LEO and on ground. With this microservice, mission planning is provided with visibility windows for satellite-to-ground-link or inter-satellite-link opportunities. In addition, the LCT-pointing information for link initialisation is provided, together with orbit data for a pair of LCTs where the state vectors of the counter terminal are included in the LCT command process. Through these examples, the Flight Dynamics microservices show feasibility within the satellite operations support segment.