A. Kereszturi

Analysis of Dark Albedo Features on a Southern Polar Dune Field of Mars

We observed 20-200 m sized low-albedo seepage-like streaks and their annual change on defrosting polar dunes in the southern hemisphere of Mars, based on the Mars Orbiter Camera (MOC), High Resolution Stereo Camera (HRSC), and High Resolution Imaging Science Experiment (HiRISE) images. The structures originate from dark spots and can be described as elongated or flowlike and, at places, branching streaks. They frequently have another spotlike structure at their end. Their overall appearance and the correlation between their morphometric parameters suggest that some material is transported downward from the spots and accumulates at the bottom of the dunes slopes. Here, we present possible scenarios for the origin of such streaks, including dry avalanche, liquid CO(2), liquid H(2)O, and gas-phase CO(2). Based on their morphology and the currently known surface conditions of Mars, no model interprets the streaks satisfactorily. The best interpretation of only the morphology and morphometric characteristics is only given by the model that implies some liquid water. The latest HiRISE images are also promising and suggest liquid flow. We suggest, with better knowledge of sub-ice temperatures that result from extended polar solar insolation and the heat insulator capacity of water vapor and water ice, future models and measurements may show that ephemeral water could appear and flow under the surface ice layer on the dunes today.

Review of Wet Environment Types on Mars with Focus on Duration and Volumetric Issues

The astrobiological significance of certain environment types on Mars strongly depends on the temperature, duration, and chemistry of liquid water that was present there in the past. Recent works have focused on the identification of signs of ancient water on Mars, as it is more difficult to estimate the above-mentioned parameters. In this paper, two important factors are reviewed, the duration and the volume of water at different environment types on past and present Mars. Using currently available information, we can only roughly estimate these values, but as environment types show characteristic differences in this respect, it is worth comparing them and the result may have importance for research in astrobiology. Impact-induced and geothermal hydrothermal systems, lakes, and valley networks were in existence on Mars over the course of from 10(2) to 10(6) years, although they would have experienced substantially different temperature regimes. Ancient oceans, as well as water in outflow channels and gullies, and at the microscopic scale as interfacial water layers, would have had inherently different times of duration and overall volume: oceans may have endured from 10(4) to 10(6) years, while interfacial water would have had the smallest volume and residence time of liquid phase on Mars. Martian wet environments with longer residence times of liquid water are believed to have existed for that amount of time necessary for life to develop on Earth between the Late Heavy Bombardment and the age of the earliest fossil record. The results of this review show the necessity for more detailed analysis of conditions within geothermal heat-induced systems to reconstruct the conditions during weathering and mineral alteration, as well as to search for signs of reoccurring wet periods in ancient crater lakes.

Planetary Science in Higher Education: Ideas and Experiences

The paper investigates how planetary science could be integrated into other courses, specifically geography and astronomy, at two universities in Hungary and the UK. We carried out both a classroom course and an online course over several years. The methods used and the experiences gained, including feedback from students and useful examples for other educators, are summarized. We found that it is possible to integrate planetary science into geography-related subjects and that planetary science can be used to encourage the students to uncover gaps in their knowledge and also to help to synthesize information they have learnt from different disciplines.

CASTAway: An asteroid main belt tour and survey

CASTAway is a mission concept to explore our Solar System’s main asteroid belt. Asteroids and comets provide a window into the formation and evolution of our Solar System and the composition of these objects can be inferred from space - based remote sensing using spectroscopic techniques. Variations in composition across the asteroid populations provide a tracer for the dynamical evolution of the Solar System. The mission combines a long-range (point source) telescopic survey of over 10,000 objects, targeted close encounters with 10–20 asteroids and serendipitous searches to constrain the distribution of smaller (e.g. 10 m) size objects into a single concept. With a carefully targeted trajectory that loops through the asteroid belt, CASTAway would provide a comprehensive survey of the main belt at multiple scales. The scientific payload comprises a 50 cm diameter telescope that includes an integrated low-resolution (R=30 – 100) spectrometer and visible context imager, a thermal (e.g. 6 – 16 μm) imager for use during the flybys, and modified star tracker cameras to detect small (~10 m) asteroids. The CASTAway spacecraft and payload have high levels of technology readiness and are designed to fit within the programmatic and cost caps for a European Space Agency medium class mission, whilst delivering a significant increase in knowledge of our Solar System.

The Astrobiological Potential of Polar Dunes on Mars

Analysis of seasonally frost-covered Martian dunes and terrestrial extremophiles in cryptobiotic crust revealed that circumpolar dark dunes on Mars form an ideal habitat for hypothetic photosynthesizing organisms on the planet. In springtime, the dark basaltic dunes show ephemeral seepage-like features on their surface, which (based on theoretical calculations) may be the result of interfacial water or bulk brine-related movement. Such a thin water film may also decompose the aggressive oxidants there. Temperature values in spring around noon could be favorable for metabolism of known extremophiles on Earth. During this warming period, the water loss could be reduced by densely packed grain structure of the soil, hygroscopic salts, and the embedding polysaccharide-like materials, as it was observed in the samples of cryptobiotic crust from hot and cold deserts on Earth. The best periods for H2O uptake are the nighttime hours.

Astrobiological characteristics and possibility of life in the polar dark dune spots of Mars

The circumpolar region of Mars was surveyed for possible habitats in the area of seasonal ice cap. Dark Dune Spots were found to be good candidates as they are covered by water ice there without carbon-dioxide ice, and show flow-like features in springtime. Based on theoretical calculations interfacial water or bulk brine may be present there that decomposes the aggressive oxidants. Temperature values in springtime around noon could be favorable for metabolism of known extremophyles on Earth, and water uptake may be possible at nighttime. During the warm daytime period the water loss could be lowered by densely packed grain structure of the soil, hygroscopic salts, and polysaccharide-like materials, as it was observed in the samples of cryptobiotic crust from hot and cold deserts on Earth. This work outlines the basic elements of these possible circumpolar microhabitats.

Luminescence spectroscopical properties of plagioclase particles from the Hayabusa Sample Return Mission: An implication for study of space weathering processes in the asteroid Itokawa

We report a systematic spectroscopical investigation of three plagioclase particles (RB-QD04-0022, RA-QD02-0025-01, and RA-QD02-0025-02) returned by the Hayabusa spacecraft from the asteroid Itokawa, by means of scanning electron microscopy, cathodoluminescence microscopy/spectroscopy, and micro-Raman spectroscopy. The cathodoluminescence properties are used to evaluate the crystallization effects and the degree of space weathering processes, especially the shock-wave history of Itokawa. They provide new insights regarding spectral changes of asteroidal bodies due to space weathering processes. The cathodoluminescence spectra of the plagioclase particles from Itokawa show a defect-related broad band centered at around 450 nm, with a shoulder peak at 425 nm in the blue region, but there are no Mn- or Fe-related emission peaks. The absence of these crystal field-related activators indicates that the plagioclase was formed during thermal metamorphism at subsolidus temperature and extreme low oxygen fugacity. Luminescence characteristics of the selected samples do not show any signatures of the shock-induced microstructures or amorphization, indicating that these plagioclase samples suffered no (or low-shock pressure regime) shock metamorphism. Cathodoluminescence can play a key role as a powerful tool to determine mineralogy of fine-grained astromaterials.

Comparison of Environment Types with Liquid Water on Mars

Various evidences on the existence of past liquid water on the Martian surface are published in the last years (for comparative review, see Carr and Hear, 2010; Head et al., 2001and references therein). Based on morphological, mineralogical and theoretical considerations, liquid water could have been on the surface of Mars at several times and at different locations in the past, producing friendly conditions for hypothetical organisms around the edge of the tolerance limit of known extremophiles on Earth (Pikuta et al., 2007).