The study analyses possible parallels of the microbialite-known structures with a set of similar settings selected by a systematic investigation from the wide record and data set of images shot by NASA rovers. Terrestrial cases involve structures both due to bio-mineralization processes and those induced by bacterial metabolism, that occur in a dimensional field longer than 0.1 mm, at micro, meso and macro scales. The study highlights occurrence on Martian sediments of widespread structures like microspherules, often organized into some higher-order settings. Such structures also occur on terrestrial stromatolites in a great variety of ‘Microscopic Induced Sedimentary Structures’, such as voids, gas domes and layer deformations of microbial mats. We present a suite of analogies so compelling (i.e. different scales of morphological, structural and conceptual relevance), to make the case that similarities between Martian sediment structures and terrestrial microbialites are not all cases of ‘Pareidolia’.

A series of experiments was carried out previously on board of the International Space Station in ‘EXPOSE-R’, a multi-user expose facility, provided by European Space Agency attached to the external surface of the Russian Segment. In one experiment, spores of microorganisms and species of higher plant seeds, in heat-sealed polymer bags were irradiated by solar radiation passed through MgF2 windows in a high space vacuum. After sample exposure, it was found that in many cases the inner surfaces of windows were contaminated. Analysis of the contamination revealed the presence of chemical groups CH2, CH3, NH, OH, C═O, Si–CH3 (Demets et al. in 2015). Their presence in deposits was explained by photofixation of gaseous precursors – some of the vapours of glues and additives in polymeric materials in the core facility of ‘Expose-R’. Carbon-, oxygen- and silicon-containing groups may be deposited from outer intrinsic atmosphere. This atmosphere is connected with sample compartments and core facility. However, the presence of NH groups on inner surfaces of windows was not expected. This paper shows that the process responsible for carbon-, nitrogen- and oxygen-containing group formation can be a photopolymerization of caprolactam, which is released from the outer Nylon 6 layer of polymer bags under Solar vacuum ultraviolet radiation.

Halophilic Archaea are known to tolerate multiple extreme conditions on Earth and have been proposed as models for astrobiology. In order to assess the importance of cold-adaptation of these microorganisms in surviving stratospheric conditions, we launched live, liquid cultures of two species, the mesophilic model Halobacterium sp. NRC-1 and the cold-adapted Antarctic isolate Halorubrum lacusprofundi ATCC 49239, on helium balloons. After return to Earth, the cold-adapted species showed nearly complete survival while the mesophilic species exhibited slightly reduced viability. Parallel studies found that the cold-adapted species was also better able to survive freezing and thawing in the laboratory. Genome-wide transcriptomic analysis was used to compare the two haloarchaea at optimum growth temperatures versus low temperatures supporting growth. The cold-adapted species displayed perturbation of a majority of genes upon cold temperature exposure, divided evenly between up-regulated and down-regulated genes, while the mesophile exhibited perturbation of only a fifth of its genes, with nearly two-thirds being down-regulated. These results underscore the importance of genetic responses of H. lacusprofundi to cold temperature for enhanced survival in the stratosphere.

The Mars Climate Simulation Chamber (MCSC) (GEO PAT 12 522/01) is designed for the investigation of the possible past and present habitability of Mars, as well as for the solution of practical tasks necessary for the colonization and Terraformation of the Planet. There are specific tasks such as the experimental investigation of the biological parameters that allow many terrestrial organisms to adapt to the imitated Martian conditions: chemistry of the ground, atmosphere, temperature, radiation, etc. MCSC is set for the simulation of the conduction of various biological experiments, as well as the selection of extremophile microorganisms for the possible Settlement, Ecopoesis and/or Terraformation purposes and investigation of their physiological functions. For long-term purposes, it is possible to cultivate genetically modified organisms (e.g., plants) adapted to the Martian conditions for future Martian agriculture to sustain human Mars missions and permanent settlements. The size of the chamber allows preliminary testing of the functionality of space-station mini-models and personal protection devices such as space-suits, covering and building materials and other structures. The reliability of the experimental biotechnological materials can also be tested over a period of years. Complex and thorough research has been performed to acquire the most appropriate technical tools for the accurate engineering of the MCSC and precious programmed simulation of Martian environmental conditions. This paper describes the construction and technical details of the equipment of the MCSC, which allows its semi-automated, long-term operation.

Sea urchin skeletons, or tests, comprise rigid calcareous plates, interlocked and sutured together with collagen fibres. The tests are malleable due to mutability in the collagen fibres that loosen during active feeding, yielding interplate gaps. We designed an extraterrestrial simulation experiment wherein we subjected actively growing sea urchins to one factor associated with zero-gravity environments, by growing them under conditions in which reactionary gravitational forces were balanced, and observed how their tests responded. Preventing tests from adhering to surfaces during active growth produced more-spherical bodies, realized as increased height-to-diameter ratios. Sea urchin tests constitute ideal systems for obtaining data that could be useful in extraterrestrial biology research, particularly in how skeletons grow under altered-gravity conditions.

The Zoo solution to Fermi's Paradox proposes that extraterrestrial intelligences (ETIs) have agreed to not contact the Earth. The strength of this solution depends on the ability for ETIs to come to agreement, and establish/police treaties as part of a so-called ‘Galactic Club’. These activities are principally limited by the causal connectivity of a civilization to its neighbours at its inception, i.e. whether it comes to prominence being aware of other ETIs and any treaties or agreements in place. If even one civilization is not causally connected to the other members of a treaty, then they are free to operate beyond it and contact the Earth if wished, which makes the Zoo solution ‘soft’. We should therefore consider how likely this scenario is, as this will give us a sense of the Zoo solution's softness, or general validity. We implement a simple toy model of ETIs arising in a Galactic Habitable Zone, and calculate the properties of the groups of culturally connected civilizations established therein. We show that for most choices of civilization parameters, the number of culturally connected groups is >1, meaning that the Galaxy is composed of multiple Galactic Cliques rather than a single Galactic Club. We find in our models for a single Galactic Club to establish interstellar hegemony, the number of civilizations must be relatively large, the mean civilization lifetime must be several millions of years, and the inter-arrival time between civilizations must be a few million years or less.

The polar regions of Mars feature layered deposits, some of which exist as enclosed zoning structures. These deposits raised strong interest since their discovery and still remain one of the most controversial features on Mars. Zoning structures that are enclosed only appear in the Northern polar region, where the disappearance of water bodies may have left behind huge deposits of evaporate salts. The origin of the layered deposits has been widely debated. Here we propose that the enclosed nature of the zoning structures indicates the result of recent tectonism. We compared similar structures at an analogue site located in the western Qaidam Basin of Tibetan Plateau, a unique tectonic setting with abundant saline deposits. The enclosed structures, which we term Ring Structures, in both the analogue site and in the Northern polar region of Mars, were formed by uplift induced pressurization and buoyancy of salts as the result of recent tectonic activity.

During the course of chemical evolution the role of metal oxides may have been very significant in catalysing the polymerization of biomonomers. The peptide bond formation of alanine (ala) and glycine (gly) in the presence of various oxides of manganese were performed for a period of 35 days at three different temperatures 50, 90 and 120°C without applying drying/wetting cycling. The reaction was monitored every week. The products formed were characterized by high-performance liquid chromatography and electrospray ionization–mass spectrometry techniques. Trace amount of oligomers was observed at 50°C. Maximum yield of peptides was found after 35 days at 90°C. It is important to note that very high temperatures of 120°C favoured the formation of diketopiperazine derivatives. Different types of manganese oxides [manganosite (MnO), bixbyite (Mn2O3), hausmannite (Mn3O4) and pyrolusite (MnO2)] were used as catalyst. The MnO catalysed glycine to cyclic (Gly)2, (Gly)2 and (Gly)3, and alanine, to cyclic (Ala)2 and (Ala)2. Mn3O4 also produced the same products but in lesser yield, while Mn2O3 and MnO2 produced cyclic anhydride of glycine and alanine with a trace amount of dimers and trimmers. Manganese of lower oxidation state is much more efficient in propagating the reaction than higher oxidation states. The possible mechanism of these reactions and the relevance of the results for the prebiotic chemistry are discussed.

In this paper, a first study of the atmospheric entry of carbonate micrometeoroids, in an astrobiological perspective, is performed. Therefore an entry model, which includes two-dimensional dynamics, non-isothermal atmosphere, ablation and radiation losses, is build and benchmarked to literature data for silicate micrometeoroids. A thermal decomposition model of initially pure magnesium carbonate is proposed, and it includes thermal energy, mass loss and the effect of changing composition as the carbonate grain is gradually converted into oxide. Several scenarios are obtained by changing the initial speed, entry angle and grain diameter, producing a systematic comparison of silicate and carbonate grain. The results of the composite model show that the thermal behaviour of magnesium carbonate is markedly different from that of the corresponding silicate, much lower equilibration temperatures being reached in the first stages of the entry. At the same time, the model shows that the limit of a thermal protection scenario, based on magnesium carbonate, is the very high decomposition speed even at moderate temperatures, which results in the total loss of carbon already at about 100 km altitude. The present results show that, although decomposition and associated cooling are important effects in the entry process of carbonate grains, the specific scenario of pure MgCO3 micrograin does not allow complex organic matter delivery to the lower atmosphere. This suggests us to consider less volatile carbonates for further studies.

Thomas Nagel in ‘The Absurd’ (Nagel 1971) mentions the future expunction of the human species as a ‘metaphor’ for our ability to see our lives from the outside, which he claims is one source of our sense of life's absurdity. I argue that the future expunction (not to be confused with extinction) of everything human – indeed of everything biological in a terran sense – is not a mere metaphor but a physical certainty under the laws of nature. The causal processes by which human expunction will take place are presented in some empirical detail, so that philosophers cannot dismiss it as merely speculative. I also argue that appeals to anthropic principles or to forms of mystical cosmology are of no plausible avail in the face of human expunction under the laws of physics.