Materials 16 (2023): 4170

doi: https://doi.org/10.3390/ma16114170, preprint available open access: doi:https://www.preprints.org/manuscript/202304.1169/v1

Once on Mars, maintenance and repair will be crucial for humans as supply chains including Earth and Mars will be very complex. Consequently, the raw material available on Mars must be processed and used. Factors such as the energy available for material production play just as important a role as the quality of the material that can be produced and the quality of its surface. To develop and technically implement a process chain that meets the challenge of producing spare parts from oxygen-reduced Mars regolith, this paper addresses the issue of low-energy handling. Expected statistically distributed high roughnesses of sintered regolith analogs are approximated in this work by parameter variation in the PBF-LB/M process. For low-energy handling, a dry-adhesive microstructure is used. Investigations are carried out to determine the extent to which the rough surface resulting from the manufacturing process can be smoothed by deep-rolling in such a way that the microstructure adheres and enables samples to be transported. For the investigated AlSi10Mg samples (12 mm × 12 mm × 10 mm), the surface roughness varies in a wide range from Sa 7.7 µm to Sa 64 µm after the additive manufacturing process, and pull-off stresses of up to 6.99 N/cm² could be realized after deep-rolling. This represents an increase in pull-off stresses by a factor of 392.94 compared to the pull-off stresses before deep-rolling, enabling the handling of even larger specimens. It is noteworthy that specimens with roughness values that were previously difficult to handle can be treated post-deep-rolling, indicating a potential influence of additional variables that describe roughness or ripples and are associated with the adhesion effect of the microstructure of the dry adhesive.

© The Authors 2023 licensed under CC BY 4.0

44th COSPAR Scientific Assembly. Held 16-24 July, 2022. Online at https://www.cosparathens2022.org/. Abstract PEX.2-0002-22.

Bibcode: 2022cosp...44.3186A

Leading space agencies have the intention to bring humans to Mars in the next decades, and some private companies push for sooner deadlines. In fact, promises and plans to land humans on Mars have recurrently been announced since the end of the Apollo era, but have remained largely incomplete or even abandoned. At the University of Bremen, we are convinced that human Mars exploration will happen and that it will have a huge impact on both humankind and on the Martian environment. Given that even optimists do not see humans on Mars before the 2030s, we believe that now is the right moment to research possible scenarios for human Mars exploration and settlement, and to study the consequences for Earth, Mars and humankind. To this end, we have formed a new research initiative "Humans on Mars - Pathways to a long-term sustainable human presence" at the University of Bremen. Our approach to human Mars exploration is transdisciplinary and human-centered. On one hand, humankind has experienced tremendous progress and increase in welfare since the Apollo era. On the other hand, we see unambiguously the immense impact of increasing population and welfare on the environmental pollution and associated climate changes. In a nutshell, while the development of new technologies has been the main driver of progress, it has also put Earth in danger. We here argue that human Mars exploration can be instrumental in leading a change from a technology-centered toward a human-centered society, thereby solving our most pressing problems on Earth. Specifically, the thin CO2 Martian atmosphere, the scarcity of energy sources and water, the difficulties to produce food and consumables, and the need for cooperative human-robotic crews, pose challenges whose solutions will enormously benefit Earth. In short, the mindset emerging from thinking under the severe constraints on Mars could be the key to making our presence on Earth sustainable. In this talk, we will present our vision and report on the progress made in selected areas, starting with the shifts in experience and demands on new ways of interaction which come with humankind's expansion to Mars. These include the interactions of the humans on Mars with the humans on Earth on one hand and their habitat and swarm of robots on the other. We will present our efforts in in-situ resource utilization, which focus on sustainable bioproduction, the extraterrestrial fabrication of metal alloys, the production with impure materials and the harvesting of energy from space radiation. 

Chemical Engineeering Science 257 (2022), 117681

doi: https://doi.org/10.1016/j.ces.2022.117681

Many systems in fluid dynamics and materials science are modelled using multiphase energy balances which can be reduced to an interface, curvature-driven mechanical problem. When simulating these systems, it is desirable to understand the details and changes of the underlying micro- and mesostructures. However, conventional numerical methods formulated in Cartesian coordinates are incapable of accurately simulating many complex systems over the space and timespans of interest. In this work, we demonstrate how modern developments in the field of discrete differential geometry can be exploited to greatly reduce the computational resources required in the simulation of multiphase systems. In particular we show how local–global theorems such as the discrete Gauss-Bonnet Theorem can be used to compute the exact mean normal- and geodesic curvatures of convex interfaces in equilibrium. In addition, we provide error estimates needed for a particular mesh refinement to retain a predetermined accuracy in the simulations. Our coordinate free formulation can be applied to any data structure used for multiphysics simulations when the underlying space of the interface is manifold. In order to validate the accuracy of the formulation with physical systems, it was applied to test cases of capillary rise, particle–particle bridges and a Sessile microdroplet system with near-exact results (subject to floating-point errors).

@ 2022 The Author(s) licensed under CC BY 4.0