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Wojtkowiak, H., Balagurin, O., Fellinger, G., Fischer, W., Garcia Fernandez, B., Kayal, H.: ASAP: Autonomous onboard mission planning. 65th International Astronautical Congress. International Astronautical Federation (2014).
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Fischer, W., Balagurin, O., Kayal, H., Wojtkowiak, H.: Hardwarenahe Softwarelösungen für Miniaturisierte Sternsensoren. 63. Deutscher Luft- und Raumfahrtkongress. Deutsche Gesellschaft für Luft- und Raumfahrt (2014).
Zur genauen Lagebestimmung von Raumfahrtsystemen sind Sternsensoren meist unabdingbar. Da die Anforderungen an die Lagekenntnis auch im Kleinsatelliten- und Cubesatbereich immer weiter steigen, müssen vermehrt neue Möglichkeiten gefunden werden bestehende Konzepte an die Anforderungen dieser Satellitenklassen anzupassen oder neue zu entwickeln. Im folgenden Beitrag wird die Entwicklung eines neuartigen Sternerkennungsalgorithmus vorgestellt, der eine sehr viel schnellere und effizientere Lagebestimmung als herkömmlichen Verfahren ermöglicht. Hierdurch soll die präzise Lagebestimmung im Kleinsatellitenbereich weiter vorangebracht werden. Die Implementierung dieses Algorithmus auf dem neuen Sternsensor Nanostar wird ebenfalls beleuchtet. Dieser wird momentan an der Universität Würzburg entwickelt und soll bis 2016 vollständig qualifiziert sein.
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Balagurin, O., Fischer, W., Kayal, H., Wojtkowiak, H.: STAR SENSOR SOLUTIONS FOR PICO AND NANOSATELLITE. Small Satellites Systems and Services - The 4S Symposium. ESA & CNES (2014).
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Balagurin, O., Fellinger, G., Fischer, W., Kayal, H., Wojtkowiak, H.: Methods and Systems for Increasing Autonomy of Earth Observation Satellites. Small Satellites Systems and Services - The 4S Symposium. ESA & CNES (2014).
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Wojtkowiak, H., Balagurin, O., Fellinger, G., Kayal, H.: ASAP: AUTONOMOUS DYNAMIC SCHEDULING FOR SMALL SATELLITES. 64th International Astronautical Congress. International Astronautical Federation (2013).
Usually planning of satellite missions is done on ground by an expert team. Activities have to be prioritized; telecommand lists have to be generated according to time-based procedures and sent to the satellite for execution. In consequence of this method expenses for operations are a major part of the overall satellite mission cost because of the usually intense involvement of humans in the planning and operations processes. Additionally, doing it this way makes it impossible to react on special short-time events such as volcanic eruptions or fires. To improve the process of mission planning, the development of a new autonomous imaging system with an integrated autonomous planning system has been started at the University of Wuerzburg which is funded through the German Aerospace Center (FKZ 50RM1208) by the Federal Ministry of Economics and Technology (BMWi). The aim is to use such a system on board of nano satellites in the future to enable autonomous fast time responses to short-lived optical phenomena. Furthermore the system can relieve the On-Board-Computer (OBC) of the satellite by providing scheduling capacities and mechanism. The main functionality of our new satellite system is twofold. On one hand, it uses its optical system to autonomously detect, classify and track (in the field of view) interesting objects or phenomena like meteors or lightning in the Earth´s atmosphere. In the context of our project, this is called “Autonomous Sensing (AS)”. On the other hand, it provides the capability and means to schedule satellite operation procedures. This feature is called “Autonomous Planning (AP)”. Combined, these acronyms form the project's name ASAP. The main feature is that both functionalities work autonomously. The focus of this paper lies on the scheduling system of ASAP. It has to manage activities and resources. One or several resources can be grouped to one hardware platform on which activities can be executed. Activities and resources can be distinguished in internal ones and external ones. Internal activities and resources are provided by ASAP and can be independently scheduled. For example the “Autonomous Sensing” functionality of ASAP is fully accomplished by internal activities and resources. External activities and resources can be registered in ASAP in order to be integrated into the scheduling process. This sort of operation requires some kind of communication. For this case ASAP offers a special interface to bind external components into the scheduling mechanism.
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Balagurin, O., Fischer, W., Kayal, H., Wojtkowiak, H.: AN AUTONOMOUS IMAGING SYSTEM WITH MISSION PLANNING CAPABILITY. 62. Deutscher Luft- und Raumfahrtkongress. Deutsche Gesellschaft für Luft- und Raumfahrt (2013).
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Wojtkowiak, H., Balagurin, O., Fellinger, G., Kayal, H.: ASAP: AUTONOMY THROUGH ON-BOARD PLANNING. 6th International Conference on Recent Advances in Space Technologies (RAST). AIAA American Institute of Aeronautics and Astronautics (2013).
Usually a satellite is entirely controlled from ground. Its tasks are planned in advance by a satellite operations team using specialized scheduling software. When the orbiting satellite enters the transmission range of the ground station, communication is possible, and a newly generated plan (if required) can be uploaded and executed in due time. Although this approach is well-established and has been used for decades, it has some major drawbacks. It binds resources (e.g. personal staff, communication links, etc.) and prohibits fast reactions to transient events, due to the required change of the currently active plan. In the traditional approach, the changes can only be achieved by transmitting a new plan from the ground station to the satellite. This communication imposes time delays which are not acceptable for fast reactions and responses. A way to overcome this problem is to equip the satellite with an autonomous decision-making system which is able to alter the operation plan onboard the satellite. The department of Computer Science VIII of the University of Wuerzburg is currently developing such a system named ASAP and will present it in this paper. The focus lies on the interaction between ASAP and the OnBoard-Computer of the satellite.
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Wojtkowiak, H., Balagurin, O., Fellinger, G., Kayal, H.: ASAP: Increasing the autonomy of small satellites. 9th IAA Symposium on Small Satellites for Earth Observation. International Academy of Astronautics (2013).
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Barschke, M., Ballheimer, W., Dornburg, L., Noack, D., Briess, K., Adirim, H., Pilz, N., Kayal, H., Balagurin, O., Wojtkowiak, H., Nitzschke, C.: TechnoSat-A Nanosatellite Mission for On-Orbit Technology Demonstration. 27th Annual AIAA/USU Conference on Small Satellites. AIAA/Utah State University (2013).
In the last 25 years, TU Berlin developed, built, launched and operated a number of university class satellites. Throughout these missions, emphasis was placed on developing technologies for Earth remote sensing, communication and attitude determination and control. The nanosatellite mission TechnoSat has the primary objective to provide on-orbit demonstration capability for novel nanosatellite technologies and components. The satellite carries five main payloads: A separation system for nanosatellites, a hatch mechanism designed for protection and on-orbit calibration of infrared cameras, a fluid dynamic actuator for energy efficient attitude control, an extendable boom system that is employed for gravity gradient stabilisation and STELLA, a miniaturised star tracker. The secondary mission objective of TechnoSat is the on-orbit verification of the novel adaptive nanosatellite bus TUBiX20 (TU Berlin innovative neXt generation 20 kg nanosatellite bus). TechnoSat is scheduled to be launched in Q4 2014.
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Kayal, H., Balagurin, O., Wojtkowiak, H.: ASAP – A Sensor System for Autonomous Event Detection and on Board Planning. 63rd International Astronautical Congress. International Astronautical Federation (2012).
Traditionally the operations planning is done on ground. User requirements are compiled, put into a priority list and telecommand lists are generated based on predefined procedures. All these planning activities are often done a few days before the commands are uplinked to the satellites, where they are executed at the intended point of time. This well established procedure has the drawback, that one can not react to transient events in the environment which may occur temporarily and might be of interest such as geysers on planets or moons, volcano eruption, fires or fireballs. Additionally the classical planning activities on ground require a significant amount of human resources, which results in high operations cost. One possible way to reduce the disadvantages of classical operations approach is to shift the planning task to the satellite. In order to be able to detect interesting event as mentioned above, the system must be capable of continuously observing the environment of interest and look for predefined features in the sensor data. A second system must then reorganize the on board command list to adapt to the new situation as soon as a interesting feature or event is detected. Within the frame of the ASAP project it is planned to develop such a system containing a image sensor, a processor for the image data and a planning system. The system will be suitable to be operated in the environment of a nano satellite. The project is funded by the German Aerospace Center, DLR (FKZ 50RM1208). The paper will describe the system motivation, the first system concept.
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Kayal, H., Balagurin, O., Wojtkowiak, H.: ASAP – AUTONOMER BILDSENSOR UND PLANUNGSSYSTEM FÜR NANOSATELLITEN. 61. Deutscher Luft- und Raumfahrtkongress. Deutsche Gesellschaft für Luft- und Raumfahrt (2012).
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Balagurin, O., Kayal, H., Wojtkowiak, H.: VALIDATION AND QUALIFICATION OF A CMOS BASED MINIATURE STAR TRACKER FOR SMALL SATELLITES. Small Satellites Systems and Services - The 4S Symposium. ESA & CNES (2012).
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Kayal, H., Balagurin, O., Wojtkowiak, H.: ASAP: A NOVEL AUTONOMOUS IMAGE SENSOR FOR EVENT DETECTION AND ON BOARD PLANNING SYSTEM. Small Satellites Systems and Services - The 4S Symposium. ESA & CNES (2012).
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Wojtkowiak, H., Balagurin, O., Kayal, H.: A NOVEL APS STAR TRACKER FOR PICO- AND NANO- SATELLITES. 62nd International Astronautical Congress. International Astronautical Federation (2011).
STELLA is a miniature star tracker for pico and nano satellites developed at the University Würzburg under financial support of DLR (FKZ 50RM0901). The star tracker features small dimensions and weight as well as low power consumption and fulfills therewith major boundary conditions and requirements of small satellites missions. This paper presents the abilities of STELLA and shows how they contribute to the overall satellite system. The paper focuses on three mayor topics: Mechanics: The paper shows and describes the core and optics of the camera and how it can be integrated into a small satellite system. Further on, the star tracker has been subjected to a full qualification program which includes thermal-vacuum, shock, vibrations and radiation tests and therefore the results will be presented. Electrics/Electronics: This part contains the different logic chips which are used in STELLA and how they communicate and work with each others. Especially the data bus, which is used for (image) data transmission, will be introduced. One special feature is the partial hardware redundancy of the power and main logic system. It can be either controlled by the On-Board-Controller (OBC) of the satellite or works completely autonomous. Software: Through its special Telecommand/Telemetry – Interface it can be adapted to different system conditions and allows access to all sub modules like memory manager, image sensor control or star recognition and attitude determination. The heart of the software is the star recognition and attitude determination program. It works together with the basic software which grants access to different resources like memory, communication busses or the image sensor itself. The software update function allows alternating the program code for all logic devices in order to adapt the behavior of STELLA. Even applications which are different to star recognition and attitude determination are possible with a suitable software update. Finally, the paper will show a listing of all essential parameters and abilities, which are proofed through tests and measurements in laboratory environment as well as field tests. Summarized it can be said, that STELLA is a new star tracker, which enables through it low mass, power and dimensions the usage in pico- and nano-satellites.
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Balagurin, O., Kayal, H., Wojtkowiak, H.: STELLA - A New Small Star Tracker for Pico and Nano Satellites. 8th IAA Symposium on Small Satellites for Earth Observation. International Academy of Astronautics (2011).
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Balagurin, O., Kayal, H., Harald, W.: TEST AND PERFORMANCE ANALYSIS OF THE NEW STAR TRACKER STELLA. 60. Deutscher Luft- und Raumfahrtkongress. Deutsche Gesellschaft für Luft- und Raumfahrt (2011).
