Spaceborne Multiple-Swath SAR Imaging with Frequency Scanning

This paper presents innovative multiple-swath SAR imaging modes making use of the frequency scanning technique (F-Scan). A novel technique is proposed for high-resolution wide-swath imaging based on analogue beamforming, a less complex and inexpensive option compared to conventional digital beamforming systems. The separation of the swaths - both in the time and in the frequency domain - is taken into account. The performance is assessed for different scenarios, confirming the high performance and high flexibility that can be achieved with the proposed imaging modes. For instance, it is shown the possibility to image a contiguous 290 km swath with a resolution below 9 m2

Bayesian Models for Uncertainty Estimation in Aerodynamic Databases of Reusable Launch Vehicles

The definition of Aerodynamic Databases (AEDBs) is an important yet very complex and labor-intensive task during the design of new aerospace vehicles. This is particularly true for Reusable Launch Vehicles (RLVs), as it has been observed during the development of CALLISTO, a demonstrator for a Vertical-Takeoff Vertical-Landing (VTVL) first stage which is jointly developed, manufactured and tested by DLR, JAXA and CNES. In this paper, we present an Inference-based methodology to define various types of Bayesian models exemplarily for a subset of CALLISTO's AEDB to assess their usability and prediction qualities. First, a short introduction to the underlying aerodynamic dataset will be given which has been aggregated from various Computational Fluid Dynamics (CFD) and Wind Tunnel Test (WTT) campaigns. Then, the different Bayesian models will be defined and their inference results compared against each other, according to common error metrics. It will be shown that, within the limits and assumptions of this study, several types of Bayesian AEDB models provide better accuracy in the prediction of uncertain aerodynamic coefficients compared to classical expert-fitted models for the given CALLISTO dataset. Generally, it can be concluded that Bayesian models are not only a promising new method for the definition of AEDBs, but could also find many potential applications in other engineering domains

Synergetic Material Utilization - ISRU activities at the DLR Institute of Space Systems - Regolith Beneficiation and Water Extraction

Sustainable space exploration requires the development of In-Situ Resource Utilization (ISRU) technologies, which encompass all processes that utilize local resources to generate useful products for robotic and human exploration. This presentation describes the ongoing projects and activities in ISRU technology development at the DLR Institute of Space Systems in Bremen, Germany

Analogue Testing of Plant Cultivation Technologies for Space

Starke Schneestürme mit Windgeschwindigkeiten von bis zu 150 Kilometern pro Stunde, Temperaturen unter minus 40 Grad Celsius, totale Isolation abgeschnitten von der Zivilisation, davon zehn Wochen in völliger Dunkelheit und keine Rettungskapsel wie auf der Internationalen Raumstation (ISS), mit der eine schnelle Rückkehr in die Heimat möglich ist. Dies sind nur einige der Herausforderungen, denen sich das EDEN ISS Team während der Weltraum-Testmission an der deutschen Neumayer-Station III des Alfred-Wegner Instituts (AWI) in der Antarktis stellen musste. Das von der Europäischen Union finanzierte Forschungsprojekt untersucht unter Leitung des Deutschen Zentrums für Luft- und Raumfahrt (DLR), wie zukünftig Pflanzen in Habitaten auf Mond und Mars angebaut werden können. Die längerfristige Präsenz von Menschen im Weltall verlangt die Entwicklung von neuen regenerativen Technologien, um Nahrungsmittel- und Sauerstoffproduktion, Abfallverwertung, Kohlendioxidreduktion, Abfallmanagement und Wasseraufbereitung zu ermöglichen und um die Besatzung gesund und psychologisch fit zu halten. EDEN ISS Partner entwickelten für das Projekt folgende Komponenten: - Neuartige Nährstoffversorgung - Hochleistungs-LED-Lichtsystem - Biodetektion und Dekontaminierung - Bildsysteme zur Überwachung des gesunden Pflanzenwachstums Während der analogen Testmission in der Antarktis lieferte das Gewächshaussystem verschiedene frische Gemüse für die 10 Mitglieder der überwinternden Crew. Projektleiter Prof. Dr. Daniel Schubert (DLR) präsentiert in seinem Vortag einen Gesamtüberblick des Projekts

Analysis and Assessment of Sustainable Materials and Construction Methods with an Emphasis on Circular Economy for a Modern Vehicle Concept

Automobiles are one of the biggest culprits of greenhouse gas emissions and a cause of environmental pollution, due to challenges inherent in operation of any facet of fossil power and utilization of non-renewables. It can be explained by the following transition, which is stimulated by the trends towards the decrease in CO2 emissions, energy consumption, and waste generation all through the life cycle of a vehicle. Like the objective of attaining the position of zero emissions, there is the union’s existing climate and energy policy mix in search of environmental equivalents in nearly every industrial domain. To tackle these issues, this thesis investigates combining sustainable materials and advanced production methods in the automotive area concentrating on Life Cycle Assessment (LCA) and Circular Economy principles. The study centres around the development of the Next Generation Vehicle Concept Zero (NGC – Zero) vehicle, which aims to minimize carbon emissions and resource consumption throughout its lifecycle. Another aspect of the work encompasses the application of novel and sustainable materials including recycled wood materials, silica aerogels and hybrid composites to be employed in car battery insulation and other interior products. This thesis utilises a detailed LCA method co-aligned with ISO 14040 & 14044 to quantify the environmental footprint of these materials across a life cycle basis. This is in terms of assessment on the extraction of raw materials, production of the parts or components, and the total performance during use, and their ultimate disposal or recycling. Finally, the circular economy approach is considered to increase sustainable resource utilisation and minimizing emissions with also the factor of recyclability

Influence of Electrode Structuring Techniques on the Performance of All‐Solid‐State Batteries

All-solid-state batteries (ASSBs) offer a promising route to safer batteries with superior energy density compared to conventional Li-ion batteries (LIBs). However, the design of the composite cathode and optimization of the underlying microstructure is one of the aspects requiring intensive research. Achieving both high energy and power density remains challenging due to limitations in ionic conductivity and active material loading. Using structure-resolved simulations, we investigate the potential of perforated and layered electrode designs to enhance ASSB performance. Design strategies showing significant performance increase in LIBs are evaluated regarding their application to ASSBs. Composite cathodes with solid electrolyte channels in the structure do not significantly increase cell performance compared to unstructured electrodes. However, the design with a two-layer cathode proves promising. The layered structure effectively balances improved ionic transport due to increased solid electrolyte fraction at the separator side and substantial active material loading through increased active material fraction at the current collector side of the cathode. Our research highlights key challenges in ASSB development and provides a clear direction for future studies in the field

Corrosion characteristics of 316L stainless steel in oxide-rich molten solar salt at 600 C

An attempt has been made in this work, to observe the influence on alloy aging by the sodium oxide (Na2O) in solar salt (60 wt% NaNO3 + 40 wt% KNO3). The accelerated aging was established by adding Na2O (0.005, 0.07,0.135 and 0.2 wt%) to the solar salt and their effect on corrosion of 316L stainless steel (SS) at 600 ◦C in that oxide-rich solar salts for 168 h in synthetic air was investigated. Corrosion is significantly more in oxide-rich solar salt compared to pure solar salt. Strikingly, the oxide scale-base metal interface is wavy in solar salt containing 0.005 % Na2O clearly shows the oxide addition to salt melt influences Cr-rich inner oxide layer formation and its selective dissolution at early stage that leads to non-uniform corrosion. Interestingly, with increase of Na2O to 0.07 %, steel corrosion proceeded uniformly by accelerated disintegration of Cr-rich inner layer and subsequent dissolution. Severe scale spallation and weight loss in nitrate melt containing 0.2 % Na2O fostering more rapid corrosion, alarming that substantial tolerance of oxide content in solar salt is ≥ 0.135 % for an acceptable corrosion of 316L SS. Despite preferential dissolution of Cr and scale degradation/spallation with increased oxide content in solar salt, the corrosion layer in all cases comprised of sodium ferrite, and Cr-rich CrFe mixed oxides with the Ni enrichment at the scale-metal interface. Competing processes between oxide scale growth, degradation and dissolution or even spallation has been discussed with an emphasis of Na2O addition to solar salt