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The goal of this project is to develop satellite components for space-based astronomical satellite payloads. Thereby advanced materials like iridium and innovative manufacturing technologies will be applied. After environmental testing and space qualifications tests it is planned to do an astronomical experiment with a stratospheric balloon or a sounding rocket. The work is embedded in ACCASI („Aschaffenburg Competence Center for Astronomical and Space Instumentation“)
X-ray telescopes usually operate in space and are quite different from astronomical telescopes for visible light. For normal angles of incidence, optical light is reflected on the mirror surface, whereas X-rays are either transmitted or absorbed. However, also high reflectivity X-rays mirrors are possible, when the incident rays direction is almost parallel to the mirror surface. Such grazing incidence mirrors are usually coated with thin layers of precious metals like iridium, gold or platinum, as this result in high X-ray reflectivity. These noble metals offer a wide range of reflection up to high photon energies, but, due to a series of absorption edges, have low reflectivity in the 2 - 4 keV band and below. This contribution presents the development of innovative material combinations based on thin layers of iridium and chromium, followed by an additional layer of carbon-based materials. We also discuss corresponding production methods (like dip coating) for enhanced reflectivity mirror coatings of future X-ray telescopes.
Im Rahmen einer bayerisch-tschechischen Kooperation entstanden zwei mechanisch baugleiche Röntgenteleskope, bestückt mit Gold- und Iridium-beschichteten Planspiegeln. Die Charakterisierung der nach dem ägyptischen Gott HORUS benannten Teleskope erfolgte an der Röntgentestanlage PANTER des Max-Plack-Instituts für extraterrestrische Physik. Diese Vakuum-Testanlage simuliert parallel auf die Teleskope einfallendes Sternenlicht, wobei hier die Strahlung aus einer Röntgenquelle in 120 Metern Abstand stammt. Die Messungen selbst fanden in einer daran angebauten 12 Meter langen Testkammer von 3,5 Metern Durchmesser statt. Im März 2021 sahen die HORUS-Teleskope zum erstem Mal Röntgenlicht. Während der Testkampagne von ca. 54 Stunden Dauer wurden 536 Einzelmessungen an den beiden Teleskopen durchgeführt, bei denen Photonenenergien und Einfallswinkel variiert wurden. Von einer empfindlichen CCD-Kamera, einem Prototyp der eROSITA-Satellitenkamera, wurden hierbei insgesamt 11.153.574 Röntgenphotonen individuell detektiert, analysiert und digital verarbeitet. Die beiden Weitwinkel-Röntgenteleskope haben eine Winkelauflösung von circa 4 Bogenminuten und eine Brennweite von rund zwei Metern.
Recent progress in nanosatellite technologies allows to consider innovative new CubeSat missions for scientific purposes. We present and evaluate the design of a small and cost effective CubeSat mission to monitor lunar meteoroid impacts by detecting their optical flashes. The poster summarizes the results of a comprehensive survey of past and recent ground based and satellite based projects focussing on lunar impact monitoring and discusses important aspects of the proposed mission and various alternatives for their solutions. Several spacecraft orbits around Moon and their usefulness for lunar impact observation are studied. In addition, we discuss the environmental risks and challenges, which such spacecraft needs to face, mainly thermal management and radiation tolerance. Finally, we present and discuss the design an optical camera suitable to detect meteoroid impacts on the lunar surface.
With ground based optical telescopes astronomers observe celestial objects over a wide spectral range. As usually three or even more reflections at telescope mirrors are involved, good reflection properties of the mirror coatings are important. The aluminum evaporation technique has been - and is still - the standard solution for the reflective coatings of large astronomical mirrors. Such coatings have excellent reflectivity in the ultraviolet and in the visible, but perform poorly in the infrared. Silver is the metal having highest reflectivity for wavelengths longward of 400 nm, but isn´t the best choice for reflectivity in the ultraviolet and for blue light. To avoid degradation by oxidation, durable silver coatings need to be protected by transmitting overcoating layers. In the presented study, different metallic coatings – including unusual ones like sputtered iridium - are characterized to identify a coating that is most suitable for the spectral range from ultraviolet to infrared. Experimental results are compared to simulations based on the complex refractive indices of these materials. Thereby dependence of incidence angle and polarization is also considered.
The EU intends to restrict the use of critical fuels in space propulsion systems. These propellants like hydrazine are chemically aggressive, toxic and carcinogenic. Space propulsion of the future should be environmentally friendly, inexpensive, and easy to handle. Aschaffenburg University and DLR are currently developing environmentally friendly technologies for future satellite engines. Thereby rocket-grade hydrogen peroxide, which is foreseen as a substitute, is converted to uncritical water vapour and oxygen by an exothermic catalytic reaction on nanostructured iridium layers. The resulting hot gases provide the required amount of thrust. The iridium catalyst layers are coated onto ceramic pellets, using RF magnetron sputtering technology. The catalytic functionality was tested afterwards at the chemical laboratories of DLR. First experimental results show a significantly higher catalytic activity for nanostructured iridium surfaces than for smoother crystalline layers.
In the years 2016 to 2018 the Bavarian-Czech Academic Agency (BTHA) funded in summary four bilateral projects between
Aschaffenburg University and CVUT Prague: JEUMICO, TRILAMICO, JODEXRA, and AXROCO. The effective combination
of equipment, manpower, and know-how of both partners resulted in the development of stress-compensated iridium
coatings for astronomical X-ray mirrors. The findings have been published at scientific conferences and in joint papers. This
poster gives a review on the social , political and educational aspects of the collaborations in form of a photo documentation.
Nickel-iron (NiFe) nanowires with a high contentof nickel and large aspect-ratio show promising characteris-tics for applications in modern micro-systems. In this study,nanowires with well-controlled diameter, height and compo-sition are fabricated using nanoporous poly-carbonate (PC)and anodized aluminum-oxide (AAO) membranes. Differ-ences between potentiostatic and pulsed deposition methodswere studied with regard to their flexibility and a recommen-dation for the best use of the individual types is given. Withthe application of the presented processes, future technolo-gies as magnetic energy-harvesting or nano-fluxgate sensorscan be improved.
Applying technologies of additive manufacturing to the field of tissue engineering created a pioneering new approach tomodelcomplex cell systemsartificially. Regarding its huge potential, bioprinting is still in its infancies and many questions are still unanswered. To address this issue, an extrusion-based bioprinting process was used to deposit human embryonic kidney (HEK) cellsin a defined pattern.It wasshownthat cells remained viable in the bioprinted construct for up to 8 days after printing (DAP). This work displays a proof of principle for a controlled cell formation which shall later be appliedtoin vitro drug screening tests.
Understanding the complexity of biological neural
networks like the human brain is one of the scientific
challenges of our century. The organization of the brain
can be described at different levels, ranging from small neural
networks to entire brain regions. Existing methods for
the description of functionally or effective connectivity are
based on the analysis of relations between the activities of
different neural units by detecting correlations or information
flow. This is a crucial step in understanding neural disorders
like Alzheimer’s disease and their causative factors.
To evaluate these estimation methods, it is necessary to refer
to a neural network with known connectivity, which is
typically unknown for natural biological neural networks.
Therefore, network simulations, also in silico, are available.
In this work, the in silico simulation of large scale neural
networks is established and the influence of different topologies
on the generated patterns of neuronal signals is investigated.
The goal is to develop standard evaluation methods
for neurocomputational algorithms with a realistic large
scale model to enable benchmarking and comparability of
different studies.