06 Fakultät Luft- und Raumfahrttechnik und Geodäsie
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7
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Item Open Access An automated system analysis and design tool for spacecrafts(2021) Ehresmann, Manfred; Herdrich, Georg; Fasoulas, StefanosIn this paper, a generic full-system estimation software tool is introduced and applied to a data set of actual flight missions to derive a heuristic for system composition for mass and power ratios of considered sub-systems. The capability of evolutionary algorithms to analyse and effectively design spacecraft (sub-)systems is shown. After deriving top-level estimates for each spacecraft sub-system based on heuristic heritage data, a detailed component-based system analysis follows. Various degrees of freedom exist for a hardware-based sub-system design; these are to be resolved via an evolutionary algorithm to determine an optimal system configuration. A propulsion system implementation for a small satellite test case will serve as a reference example of the implemented algorithm application. The propulsion system includes thruster, power processing unit, tank, propellant and general power supply system masses and power consumptions. Relevant performance parameters such as desired thrust, effective exhaust velocity, utilised propellant, and the propulsion type are considered as degrees of freedom. An evolutionary algorithm is applied to the propulsion system scaling model to demonstrate that such evolutionary algorithms are capable of bypassing complex multidimensional design optimisation problems. An evolutionary algorithm is an algorithm that uses a heuristic to change input parameters and a defined selection criterion (e.g., mass fraction of the system) on an optimisation function to refine solutions successively. With sufficient generations and, thereby, iterations of design points, local optima are determined. Using mitigation methods and a sufficient number of seed points, a global optimal system configurations can be found.Item Open Access Cluster of electric thrusters for astronautic and robotic INPPS flagship space flights to Mars and Europa moon(2023) Jansen, Frank; Andreussi, Tommaso; Cesarretti, Giovanni; Ehresmann, Manfred; Grill, Julia; Herdrich, Georg; Funaki, Ikkoh; Girard, Nathalie; Grundmann, Jan Thimo; Krejci, David; Leiter, Hans; Masson, Frederic; Maiwald, Volker; Misuri, Tommaso; Oriol, Stephane; Piragino, Antonio; Reissner, Alexander; Schanz, LarsThis review deals with the selection of the electric propulsion system (EPS) for the internationally developed and designed, primary nuclear-electric space tug International Nuclear Power and Propulsion System (INPPS). INPPS is scheduled for interplanetary missions to Mars and Jupiter moon Europa missions by the end of decade 2020. Regarding specific technical and mission parameters preselected electric thruster (ET) types, developed by international companies and institutions, are analysed, evaluated and investigated for a possible application as propulsion system (PS), the so-called CET (Cluster of Electric Thrusters). It is analysed whether solely electric thrusters, combined in an adequate CET, enable the envisaged interplanetary missions-robotic and astronautic/crewed with the INPPS flagship. Thruster clusters with strategic consortium considerations are analysed as a feasible PS of the INPPS. The studied CET consists of the following: (a) only European ETs, (b) combination of German and European ETs, (c) Japanese and European ETs or at least (d) Japanese, European and US thrusters. The main results are (1) Robotic and crewed INPPS mission to Mars/Europa are realizable with EPS only (no chemical propulsion is needed), (2) that every CET, except (c) of only Japanese and part of European thrusters, is capable to perform the main part of envisaged INPPS flagship mission orbit to Mars, back to Earth and to Jupiter/Europa moon.Item Open Access Development of a ferrofluid-based attitude control actuator for verification on the ISS(2024) Zajonz, Sebastian; Korn, Christian; Großmann, Steffen; Dietrich, Janoah; Kob, Maximilian; Philipp, Daniel; Turco, Fabrizio; Steinert, Michael; O’Donohue, Michael; Heinz, Nicolas; Gutierrez, Elizabeth; Wagner, Alexander; Bölke, Daniel; Sütterlin, Saskia; Schneider, Maximilian; Remane, Yolantha; Kreul, Phil; Wank, Bianca; Buchfink, Manuel; Acker, Denis; Hofmann, Sonja; Karahan, Bahar; Ruffner, Silas; Ehresmann, Manfred; Schäfer, Felix; Herdrich, GeorgFerrofluid-based systems provide an opportunity for increasing the durability and reliability of systems, where mechanical parts are prone to wear and tear. Conventional reaction control systems are based on mechanically mounted rotating disks. Due to inherent friction, they suffer from degradation, which may eventually lead to failure. This problem is further intensified due to the limited possibility for repair and maintenance. Ferrofluid-based systems aim to replace mechanical components by exploiting ferrofluidic suspended motion. Ferrofluids consist of magnetic nanoparticles suspended in a carrier fluid and can be manipulated by external magnetic fields. This paper describes the working principle, design, and integration of a working prototype of a ferrofluid-based attitude control system (ACS), called Ferrowheel. It is based on a stator of a brushless DC motor in combination with a rotor on a ferrofluidic bearing. The prototype will be verified in a microgravity environment on the International Space Station, as part of the Überflieger 2 student competition of the German Aerospace Center. First ground tests deliver positive results and confirm the practicability of such a system.Item Open Access Neutron imaging investigation of additively manufactured tungsten nozzles for an arcjet deorbit system(2025) Skalden, Jonathan; Ehresmann, Manfred; Becatti, Giulia; Schulz, Michael; Gustschin, Alex; Rebelo Kornmeier, Joana; Kis, Zoltán; Szentmiklósi, László; Herdrich, GeorgThe Institute of Space Systems is currently developing a deorbit module based on thermal arcjet technology to allow fast orbit decay at end-of-life, with a focus on megaconstellation satellites. By employing additive manufacturing with tungsten, improved nozzle geometries can lead to a gain in overall performance. However, reproducibility is an ongoing concern for additively manufactured parts. Together with the Heinz Maier-Leibnitz Zentrum (MLZ) and the Budapest Neutron Centre of the Centre for Energy Research, a study was conducted scanning additively manufactured arcjet nozzles prior to and after standardized operation via neutron computed tomography. The results show a drop in performance over time, which can be related to changes in the constrictor geometry. Furthermore, cavities created during manufacturing can significantly influence operation.Item Open Access Ferrofluid reaction wheel development and in-orbit verification(2025) Ehresmann, Manfred; Zajonz, Sebastian; Korn, Christian; Großmann, Steffen; Dietrich, Janoah; Kob, Maximilian; Philipp, Daniel; Turco, Fabrizio; Steinert, Michael; O’Donohue, Michael; Heinz, Nicolas; Gutierrez, Elizabeth; Wagner, Alexander; Bölke, Daniel; Sütterlin, Saskia; Schneider, Maximilian; Remane, Yolantha; Kreul, Phil; Wank, Bianca; Buchfink, Manuel; Acker, Denis; Hofmann, Sonja; Karahan, Bahar; Ruffner, Silas; Schäfer, Felix; Herdrich, GeorgIn contemporary satellite systems, the Attitude and Orbit Control System (AOCS) manages internal torque generation primarily through Reaction Wheels (RW) and Control Moment Gyros (CMG), which use mechanically mounted rotating disks to control orientation without expelling mass. Unlike magnetorquers, which interact with Earth’s magnetic field, or thruster-based Reaction Control Systems (RCS), which generate external forces by expelling propellant, RW and CMG systems rely solely on momentum exchange within the spacecraft. While state-of-the-art RWs are highly reliable and have demonstrated exceptional performance over decades of operation, their design still presents inherent challenges, such as wear, nonlinear friction effects, and tribological degradation of contact surfaces. These challenges are critical in space, where repairs are impractical and/or resource-intense. Consequently, engineers have devoted significant effort to developing robust and reliable mechanical reaction wheels. This paper explores an innovative proof-of-concept design based on a fluid-magnetic system utilizing ferrofluids and permanent magnets. This study aims to address limitations of traditional RWs by eliminating mechanical interfaces susceptible to wear and tear and replacing them with a low friction ferrofluidic bearing. Ferrofluid-based system concepts can offer a longer life due to reduced wear and tear, lower production costs by requiring less exotic materials and tolerances, self-center within the provided magnetic potential field and can therefore exhibit reduced vibration behavior. The Ferrowheel experiment, flown as part of the FARGO mission ( Überflieger 2 competition of the space agency within DLR) in March and April 2023, demonstrated the feasibility of ferrofluidic bearings for attitude control in ISS microgravity. These results contribute to exploration of innovative reaction wheel technologies, highlighting the potential of fluid-based systems for applications requiring enhanced robustness and reduced mechanical wear.Item Open Access Fargo : validation of space-relevant ferrofluid applications on the ISS(2024) Sütterlin, Saskia; Bölke, Daniel; Ehresmann, Manfred; Heinz, Nicolas; Dietrich, Janoah; Karahan, Bahar; Kob, Maximilian; O’Donohue, Michael; Korn, Christian; Grossmann, Steffen; Philipp, Daniel; Steinert, Michael; Acker, Denis; Remane, Yolantha; Kreul, Phil; Schneider, Maximilian; Zajonz, Sebastian; Wank, Bianca; Turco, Fabrizio; Buchfink, Manuel; Gutierrez, Elizabeth; Hofmann, Sonja; Ruffner, Silas; Wagner, Alexander; Breitenbücher, Laura; Schäfer, Felix; Herdrich, Georg; Fasoulas, StefanosThe Ferrofluid Application Research Goes Orbital (FARGO) project desires to harness the potential of ferrofluids for advanced space system applications. Thereby, the student-led research project aims to develop, evaluate and subsequently validate three different ferrofluid-based applications on board the International Space Station (ISS): a novel attitude control system called Ferrowheel as well as a Thermal and an Electrical Switch. The project is part of the Überflieger2 competition of the German Aerospace Center (DLR) in cooperation with the Luxembourg Space Agency (LSA). Central to this study is the role of ferrofluids in ensuring the functional principles to minimize the number of moving components ultimately. Therefore, the proposed systems have the potential to mitigate wear, reduce friction, and consequently improve the longevity and reliability of space systems. In the Ferrowheel, a disc is supported on ferrofluid cushions instead of conventional ball-bearing-mounted rotors. This innovative approach, facilitated by the magnetic pressure positioning of the ferrofluid, eliminates the need for solid-to-solid contact. Circularly arranged coils function as the stator, propelling the disc with a 3-phase control, resulting in a spinning magnetic field. In addition to determining the generated torque, the objective is to validate experiments on system operations in which various acceleration and deceleration manoeuvres, as well as the stored angular momentum, are evaluated. The Electrical Switch leverages a self-manufactured magnetorheological fluid (MRF) developed by augmenting a liquid-metal base with iron powder. As a result, the fluid, akin to ferrofluid, has a magnetic field-responsive movement. Since a liquid metal is used as the base, the ferrofluid-like fluid acts as both the magnetically actuatable and the current conducting fluid. To enable a current flow, the fluid is brought between the two electrical contacts utilizing electropermanent magnets (EPMs). These magnets combine the high magnetic field strengths of permanent magnets with the adaptive switching capability of electromagnets. Compared to all other demand-controlled magnetic field sources, this results in the great advantage that no energy is consumed as long as they are in one state. Only the switching process of the EPMs itself requires a high amount of energy, but only for a relatively short period. The switching behaviour under different loads will be investigated, evaluated, and compared to reference data recorded on Earth. The design of the Thermal Switch is characterized by the fact that it can be actively switched. Active thermal switching is still a relatively new field, so there is little comparative data from industrial solutions. Particularly for spacecraft, thermal design is crucial because the harsh environment of space must be taken into account. In addition to the challenge that heat can only be transferred to the environment via thermal radiation, severe conditions in space are characterized by extreme temperature differences. While extreme heat develops on the satellite surface on the side facing the sun, the opposite is valid on the shaded side. The resulting heat flow, which is irregular in time, location, and direction, leads to temperature peaks and gradients that can affect the system’s performance, functionality, and reliability. Active switching provides selective control over heat transfer, allowing more flexible temperature regulation in critical areas and implementing a dynamic system response. Different design ideas are tested and evaluated for the applications in various experiments. The most suitable design is finally selected, further modified, and tailored for experimentation on the ISS and presented in this study. The most significant challenge is the time-critical factor of only a 1-year development phase. A total of 21 students from six different courses of study and two supervising PhD students from the Institute of Space Systems are involved in the FARGO project, all members of the small satellite student society at the University of Stuttgart, KSat e.V.