Searcharxiv⌕ Search

arXiv subjects

Akos Kereszturi

Publications and source records attributed to Akos Kereszturi.

6 recordsLinked to original sources
arXiv2026

Current water trapping micro-habitats on the surface of Mars

This paper presents a conceptual model exploring how liquid water could be maintained in direct contact with hypothetical microorganisms during warm daytime periods on Mars. Hygroscopic surface salts (e.g., NaCl, CaCl$_2$, Ca(ClO$_4$)$_2$, gypsum, MgSO$_4$) can absorb water vapor and form liquid solutions; however, daytime exposure normally causes rapid drying. We propose a mechanism where diurnal temperature fluctuations drive thermal expansion and contraction cycles that open and close micro-cracks in salt crystals. Nighttime-condensed deliquescent liquid penetrates these fractures, which then partially close during warmer daytime hours, trapping liquid water inside and preventing immediate evaporation. Thermally induced volume changes (ranging from ~0.5-0.9% in crystalline phases up to several percent in concentrated solutions) support the feasibility of this cyclic aperture dynamic. Modeling deliquescence and salt distribution indicates that nighttime microscopic liquid can form for ~100-130 sols per Martian year near Acidalia Planitia. At depths of 2-3 mm within soil or salt structures, hypothetical microorganisms would gain partial UV shielding while retaining access to visible light. Overall, internal crystal micro-fractures may offer transient daytime liquid microenvironments, highlighting these locations as potential candidate habitats for photosynthetic life on modern Mars.This study serves as a conceptual feasibility analysis for near-surface brine retention within hygroscopic salt structures under present-day Martian conditions.

astro-ph.EP↗
arXiv2021

Mars: new insights and unresolved questions

Mars exploration motivates the search for extraterrestrial life, the development of space technologies, and the design of human missions and habitations. Here we seek new insights and pose unresolved questions relating to the natural history of Mars, habitability, robotic and human exploration, planetary protection, and the impacts on human society. Key observations and findings include:(1)high escape rates of early Mars' atmosphere, including loss of water, impact present-day habitability;(2)putative fossils on Mars will likely be ambiguous biomarkers for life;(3)microbial contamination resulting from human habitation is unavoidable;(4)based on Mars' current planetary protection category, robotic payload(s) should characterize the local martian environment for any life-forms prior to human habitation. Some of the outstanding questions are:(1)which interpretation of the hemispheric dichotomy of the planet is correct;(2)to what degree did deep-penetrating faults transport subsurface liquids to Mars' surface;(3)in what abundance are carbonates formed by atmospheric processes;(4)what properties of martian meteorites could be used to constrain their source locations;(5)the origin(s) of organic macromolecules;(6)was/is Mars inhabited;(7)how can missions designed to uncover microbial activity in the subsurface eliminate potential false positives caused by microbial contaminants from Earth;(8)how can we ensure that humans and microbes form a stable and benign biosphere;(9)should humans relate to putative extraterrestrial life from a biocentric viewpoint (preservation of all biology), or anthropocentric viewpoint of expanding habitation of space? Studies of Mars' evolution can shed light on the habitability of extrasolar planets. In addition, Mars exploration can drive future policy developments and confirm (or put into question) the feasibility and/or extent of human habitability of space.

astro-ph.EP↗
arXiv2019

ASIME 2018 White Paper. In-Space Utilisation of Asteroids: Asteroid Composition -- Answers to Questions from the Asteroid Miners

In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid science themes: 1) Potential Targets, 2) Asteroid-Meteorite Links, 3) In-Situ Measurements and 4) Laboratory Measurements. The Answers to those Questions were provided by the scientists with their conference presentations and collected by A. Graps or edited directly into an open-access collaborative Google document or inserted by A. Graps using additional reference materials. During the ASIME 2018, first day and second day Wrap-Ups, the answers to the questions were discussed further. New readers to the asteroid mining topic may find the Conversation boxes and the Mission Design discussions especially interesting.

astro-ph.EP↗
arXiv2017

Laboratory experiments on the low temperature formation of carbonaceous grains in the ISM

The life-cycle of cosmic dust grains is far from being understood and the origin and evolution of interstellar medium (ISM) grains is still under debate. In the ISM, the cosmic dust destruction rate is faster than the production rate by stellar sources. However, observations of ISM refractory matter suggest that to maintain a steady amount of cosmic grains, some supplementary production mechanism takes place. In this context, we aimed to study possible re-formation mechanisms of cosmic grains taking place at low temperature directly in the ISM. The low temperature condensation of carbonaceous materials has been investigated in experiments mimicking the ISM conditions. Gas-phase carbonaceous precursors created by laser ablation of graphite were forced to accrete on cold substrates (T about 10 K) representing surviving dust grains. The growing and evolution of the condensing carbonaceous precursors have been monitored by MIR and UV spectroscopy under a number of experimental scenarios. It is demonstrated, for the first time, the possibility to form ISM carbonaceous grains in "situ". The condensation process is governed by carbon chains that first condense into small carbon clusters and finally into more stable carbonaceous materials, which structural characteristics are comparable to the material formed in gas-phase condensation experiments at very high temperature. We also show that the so-formed fullerene-like carbonaceous material is transformed into a more ordered material under VUV processing. The cold condensation mechanisms here discussed can give fundamental clues to fully understand the balance between the timescale for dust injection, destruction and re-formation in the ISM.

astro-ph.GA↗
arXiv2017

ASIME 2016 White Paper: In-Space Utilisation of Asteroids: "Answers to Questions from the Asteroid Miners"

The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 conference on September 21-22, 2016 in Luxembourg City was to provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilize asteroids. The ASIME 2016 Conference produced a layered record of discussions from the asteroid scientists and the asteroid miners to understand each other's key concerns and to address key scientific questions from the asteroid mining companies: Planetary Resources, Deep Space Industries and TransAstra. These Questions were the focus of the two day conference, were addressed by scientists inside and outside of the ASIME Conference and are the focus of this White Paper. The Questions from the asteroid mining companies have been sorted into the three asteroid science themes: 1) survey, 2) surface and 3) subsurface and 4) Other. The answers to those Questions have been provided by the scientists with their conference presentations or edited directly into an early open-access collaborative Google document (August 2016-October 2016), or inserted by A. Graps using additional reference materials. During the ASIME 2016 last two-hours, the scientists turned the Questions from the Asteroid Miners around by presenting their own key concerns: Questions from the Asteroid Scientists . These answers in this White Paper will point to the Science Knowledge Gaps (SKGs) for advancing the asteroid in-space resource utilisation domain.

astro-ph.EP↗