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Im Rahmen von "Responsive Space" wird das Missionsbetriebssystem V3C (Verlegefähiges Compact Control Center) entwickelt. V3C ist auf handelsüblicher mobiler Hardware integriert, wird autark betrieben und kann schnell an verschiedene Orte verlegt werden.Wir zeigen Design, Implementierung und Bereitstellung von V3C, berichten über den erfolgreichen Demonstrationsbetrieb des BORIS-Satelliten und beleuchten verschiedene Betriebskonzepte, insbesondere die Koppelung mit einem GEO-Relais-Link.

To fulfill the objectives of deep space missions, such as in situ measurements at an outer planet’s moon or investigations at main belt asteroids, spacecraft must be provided with sufficient energy to get to these distant objects. This energy, expressed with the so-called ∆V -budget, which is the sum of required velocity changes along a spacecraft’s trajectory. As today’s and future deep space missions are infeasible using chemical propulsion alone, their trajectories involve one or more close flybys at mass-rich celestial bodies to gain additional orbit energy. These maneuvers are called gravity assists and depend on the relative positions of the assisting body and the respective target. Due to the orbital motion of both bodies, the required constellation may however repeat only every few decades. This constrains both trajectory and mission design and small launch windows can be the result. Any project delay hence threatens an on-time launch and thus potentially puts an entire mission at risk. Mitigation of that risk is possible through using low-thrust propulsion which can provide the required ∆V of a deep space mission without gravity assists. Contrary to chemical propulsion, having thrust values up to kilo-Newtons at specific impulse (Isp) values of 300-400 s, low-thrust propulsion currently offers only approximately one Newton at maximum. This thrust is achieved either through the ejection of carried-along particles, which are accelerated to very high velocities, or the reflection of sunlight photons. High exhaust gas velocities and very low propellant consumption make the respective Isp of low-thrust propulsion one magnitude higher than for chemical propulsion. The low-thrust propulsion concept of solar sailing even utilizes the solar radiation pressure for the generation of thrust, making it independent on any propellant. The different characteristics of low-thrust propulsion and chemical propulsion result in different trajectories. Therefore the methods for the optimization of trajectories of chemically propelled spacecraft are of limited use for the optimization of low-thrust trajectories. New methods were developed for this purpose, and one of them is Evolutionary Neurocontrol. This global optimization method combines the two biology-inspired mechanisms artificial neural networks and evolutionary algorithms. Called neurocontrollers, the artificial neural networks are used for spacecraft control. The optimization capability of evolutionary algorithms is used for the training of neurocontrollers. Contrary to other optimization methods, Evolutionary Neuroncontrol does not require an initial guess solution to work, which increases its usability for non-experts in optimal control and optimization. Evolutionary Neurocontrol was applied successfully in the past to various low-thrust transfer problems. Each of those problems, however, consisted of only one single heliocentric transfer from one celestial body to another. The problem of global optimization of multiphase low-thrust trajectories remained unsolved. This thesis describes how Evolutionary Neurocontrol can be extended to multiphase low-thrust transfers. An existing implementation was revised and complemented with new capabilities, concepts, and functionalities. Examples of the new features are a generic multiphase simulation framework, the support of nonheliocentric transfers, and third-body perturbation. The resulting method has been validated on various complex low-thrust transfer problems, which included two-phase transfers, like Earth-Moon-transfers, or heliocentric rendezvous missions with multiple targets or multiple propulsion technolgies. If available, the results were compared with published reference solutions. Finally, Evolutionary Neurocontrol was successfully applied to the design of a trajectory for a so-called Interstellar Heliopause Probe mission. Including a close flyby at Jupiter and using two different propulsion technologies, the resulting transfer brought the spacecraft to a heliocentric distance of 200 AU in less than 25 years.

Dieser Bericht gibt eine Zusammenfassung des PRISMA Missionsbetriebs durch das GSOC sowie eine Übersicht über die erzielten Ergebnisse. In Kapitel 3 werden zunächst die Zielsetzungen des Vorhabens sowie die Rahmenbedingungen beschrieben, unter denen das Projekt durchzuführen war. Anschließend gibt Kapitel 4 eine Übersicht über den Projektverlauf und beschreibt die wichtigsten Ereignisse. Kapitel 5 beschreibt die wichtigsten Ergebnisse des Vorhabens und schildert gemachte Erfahrungen.

The experimental satellite project PRISMA was initiated in 2005 by Sweden, France, Denmark, and Germany, with the Swedish Space Cooperation (SSC) as the project lead. The purpose was the demonstration of necessary techniques and the validation of the respective sensor technology for future missions that involve close formation flight and rendezvous in space. At that time, the German Aerospace Center DLR was not only involved in providing satellite GPS hardware and navigation software components but also as one of the experimenters for GPS-based navigation and autonomous formation flight. The idea of also conduction a part of the flight operations phase from Germany came into discussion at the end of 2009, with the purpose of sharing mission operations cost. This was agreed by Sweden and Germany shortly before launch of the two PRISMA satellites, which took place in June 2010. Nine months later, mission operations were handed over from SSC’s control center in Solna, Stockholm, to the German Space Operations Center (GSOC) in Oberpfaffenhofen, Germany. After successful operations by GSOC, the re-hand over of the mission back to Solna was performed in August 2011. The baseline concept for the German PRISMA ground segment foresaw cloning of the Swedish ground segment developed by SSC at GSOC to minimize the development and test effort, but specific adaptations were needed to integrate PRISMA into GSOC’s multimission environment. Furthermore, the original station network, which consisted only of the Kiruna ground station in North Sweden, was extended by two additional DLR ground stations in Weilheim, Germany, and in Inuvik, Canada. That extension proved especially beneficial to the shift concept. Another important aspect was the training of the German operations personnel in a short time. This was realized by training on the job concept, which kept the additional workload for teaching and training on acceptable levels and at the same time supported the Swedish flight operations team during their operations phase. This paper gives an overview of the GSOC ground segment and the flight operations activities. It reflects the challenges with regard to personnel and to the technical implementation of PRISMA flight operations at GSOC with limited available time. It also summarizes the lessons learned after five months of successful flight operations.