According to the Kardashev scale, possible Type-II and above civilizations could use energy sources of the universe in different ways. Self-replicator von Neumann probes believed to invade any galaxies in various studies could also have uses for gaining energy, in which Dyson swarm structures are likely to consist of probes that could emit energy from any luminous celestial object is to be considered first. On addressing some possible dynamical properties of probes, the study has examined in which size and populations they could enfold a star and how they could have observational evidences according to relevant star's energy output. On the basis of our solar system, it has also been shown using a weighted-directed network structure what kind of population and route they could have in case of spreading to the nearest-neighbouring stars.

With the increase of crewed space missions and the rise of space microbiology, the research of microbes grown under microgravity environment has been attracting more attention. The research scope in space microbiology has been extended beyond pathogens directly related to spaceflight. Y. pestis, the causative agent of plague, is also of interest to researchers. After being cultivated for 40 consecutive passages in either simulated microgravity (SMG) or normal gravity (NG) conditions, the Y. pestis strain 201 cultures were analysed regarding their phenotypic features. By using crystal violet staining assays, increased biofilm amount was detected in Y. pestis grown under SMG condition. Besides that, the damage degrees of Hela cell caused by SMG-grown Y. pestis were found diminished in comparison to those under NG condition. Consistent with this observation, the death course was delayed in mice infected with SMG-grown Y. pestis, suggesting that microgravity condition can contribute the attenuated virulence. RNA-seq-based transcriptomics analysis showed that a total of 218 genes were differentially regulated, of which 91 upregulated and 127 downregulated. We found that dozens of virulence-associated genes were downregulated, which partially explained the reduced virulence of Y. pestis under SMG condition. Our study demonstrated that long-term exposure to SMG influences the pathogenesis and biofilm formation ability of Y. pestis, which provides a novel avenue to study the mechanism of physiology and virulence of this pathogen. Microgravity enhanced the ability of biofilm formation and reduced the virulence and cytotoxicity of Y. pestis. Many virulence-associated genes of Y. pestis were differentially regulated in response to the stimulated microgravity. However, there is no molecular evidence to explain the enhanced biofilm formation ability, which requires further research. Taken together, the phenotype changes of Y. pestis under SMG conditions can provide us a new research direction of its potential pathogenesis.

In the search for extraterrestrial life and intelligence, it is essential to clarify what is to be meant by ‘life’ and ‘intelligence’. I first analyse what it means to ‘define’ these words. I will show that some philosophical prejudice is unavoidable. As a working hypothesis, I consider two types of philosophy: ‘natural philosophy’, seeking for some essence of things, and ‘critical (or analytical) philosophy’, devoted to the analysis of the procedures by which we claim to construct a reality. An extension of critical philosophy, epistemo-analysis (i.e. the psycho-analysis of concepts) is presented and applied to the definition of exolife and to extraterrestrial ‘intelligence’. Some pragmatic conclusions are finally drawn for future search strategies.

Since their discovery, submarine hydrothermal vent systems have been pointed out as important places where chemical evolution on Earth could have occurred; and their role in the process has been highlighted. Similarly, some hypotheses have considered these systems in origin of life scenarios. In this way, many experiments have been developed, and the knowledge about these systems has increased. Due to their complexity, many experimental simulations have only included a few of the geochemical variables present in these environments, pressure and temperature. Other main variables have hardly been included, such as mineralogy, thermal and pH gradients, dissolved ions and/or redox reactions. As it has been understood, the dynamism and heterogeneity of these environments are huge, and it comprises different scales, from single vents to full hydrothermal fields. However, the vast majority of experiments focus on a specific part of these systems and do not include salinity, mineralogy and pH gradients. For this reason, in this paper, we pointed out some considerations about how this dynamism can be interpreted, and included in some models, as well their importance in prebiotic chemistry experiments and their extrapolations regarding the hypothesis about the origins of life.

Is our current concept of sustainable development too focused on our planet? Do we need a new conception of sustainability? The recent call for an 'ethics of planetary sustainability' by A. Losch may be understood as promoting an affirmative answer to this question. This essay analyses and assesses the introduction of a new concept of sustainability from the perspective of conceptual engineering. The central question is whether this new concept, which I call ‘transplanetary sustainability’, may improve our thinking, and, indirectly, our practices. I argue that a new notion of transplanetary sustainability advantageously points to considerations that matter from a moral point of view. It may also help us to be more exact and consistent in our moral thinking. At the same time, there are serious doubts as to how fundamental the concept of sustainability as such is from a theoretical perspective since it does not figure in prominent moral theories. Furthermore, in view of possible extraterrestrial beings that deserve to be taken into account from a moral point of view, the proposed revision of the concept may reach less than required. Nevertheless, since sustainability has had an impressive career in international politics, it is practically speaking important that sustainability be conceived such that outer space is taken into account.

Spectroscopic investigations of surface mineral components, expected to exist on the surface of Mars, using multiple spectral ranges and techniques, are vital to obtain the ground truth information or reference data for Mars exploration missions. This paper presents visible, near-infrared, thermal infrared reflectance and thermal infrared transmission spectra, as well as X-ray diffraction and scanning electron microscope/energy dispersive X-ray analyses of salt crusts and sediments interleaved with cyanobacterial materials from a coastal zone of the United Arab Emirates, where sabkhas exist. The samples obtained from sabkhas were characterized because they contain minerals requiring the water for formation and they provide a possible environment for some of the earliest organisms on Earth. The surface minerals identified include gypsum, calcite, halite, aragonite and dolomite. These sediments were found to be mixed with each other and intermingled with an algal mat, which consisted of cyanobacteria. If such materials formed in similar environments on Mars, their identification would be important for understanding the geobiological conditions of the planet and the potential habitability for life.

There is no doubt that stability studies are of great importance in the fascinating research of extrasolar planetary systems. Even if most of the more than 300 extrasolar planets orbit their host stars as single giant planet and build simple two-body systems, we should not exclude the possibility that these systems could host other (small) planets that have not yet been detected due to obsevational limits. Another aspect to carry out stability studies is the growing interest in the search for extraterrestrial life in the universe. The long-term stability of a planetary system is one of the basic requirements for the evolution of life on a terrestrial planet. In this paper the dynamical behaviour of Earth-like planets will be discussed in single-star single-giant-planet systems, multi-planet systems and binary systems.

In two recent papers (Maccone 2013, 2014) as well as in the book (Maccone 2012), this author described the Evolution of life on Earth over the last 3.5 billion years as a lognormal stochastic process in the increasing number of living Species. In (Maccone 2012, 2013), the process used was ‘Geometric Brownian Motion’ (GBM), largely used in Financial Mathematics (Black-Sholes models). The GBM mean value, also called ‘the trend’, always is an exponential in time and this fact corresponds to the so-called ‘Malthusian growth’ typical of population genetics. In (Maccone 2014), the author made an important generalization of his theory by extending it to lognormal stochastic processes having an arbitrary trend mL(t), rather than just a simple exponential trend as the GBM have.

The author named ‘Evo-SETI’ (Evolution and SETI) his theory inasmuch as it may be used not only to describe the full evolution of life on Earth from RNA to modern human societies, but also the possible evolution of life on exoplanets, thus leading to SETI, the current Search for ExtraTerrestrial Intelligence. In the Evo-SETI Theory, the life of a living being (let it be a cell or an animal or a human or a Civilization of humans or even an ET Civilization) is represented by a b-lognormal, i.e. a lognormal probability density function starting at a precise instant b (‘birth’) then increasing up to a peak-time p, then decreasing to a senility-time s (the descending inflexion point) and then continuing as a straight line down to the death-time d (‘finite b-lognormal’).

1. (1) Having so said, the present paper describes the further mathematical advances made by this author in 2014–2015, and is divided in two halves: Part One, devoted to new mathematical results about the History of Civilizations as b-lognormals, and

2. (2) Part Two, about the applications of the Evo-SETI Theory to the Molecular Clock, well known to evolutionary geneticists since 50 years: the idea is that our EvoEntropy grows linearly in time just as the molecular clock.

   1. (a) Summarizing the new results contained in this paper: In Part One, we start from the History Formulae already given in (Maccone 2012, 2013) and improve them by showing that it is possible to determine the b-lognormal not only by assigning its birth, senility and death, but rather by assigning birth, peak and death (BPD Theorem: no assigned senility). This is precisely what usually happens in History, when the life of a VIP is summarized by giving birth time, death time, and the date of the peak of activity in between them, from which the senility may then be calculated (approximately only, not exactly). One might even conceive a b-scalene (triangle) probability density just centred on these three points (b, p, d) and we derive the relevant equations. As for the uniform distribution between birth and death only, that is clearly the minimal description of someone's life, we compare it with both the b-lognormal and the b-scalene by comparing the Shannon Entropy of each, which is the measure of how much information each of them conveys. Finally we prove that the Central Limit Theorem (CLT) of Statistics becomes a new ‘E-Pluribus-Unum’ Theorem of the Evo-SETI Theory, giving formulae by which it is possible to find the b-lognormal of the History of a Civilization C if the lives of its Citizens Ci are known, even if only in the form of birth and death for the vast majority of the Citizens.

   2. (b) In Part Two, we firstly prove the crucial Peak-Locus Theorem for any given trend mL(t) and not just for the GBM exponential. Then we show that the resulting Evo-Entropy grows exactly linearly in time if the trend is the exponential GMB trend.

   3. (c) In addition, three Appendixes (online) with all the relevant mathematical proofs are attached to this paper. They are written in the Maxima language, and Maxima is a symbolic manipulator that may be downloaded for free from the web.

In conclusion, this paper further increases the huge mathematical spectrum of applications of the Evo-SETI Theory to prepare Humans for the first Contact with an Extra-Terrestrial Civilization.

The permanently frozen volcanic sediment is one of the most promising geological objects for searching life on Mars. On Earth, volcanic intrusions into permafrost result in formation of the unique microbial communities. We propose several terrestrial analogues of Martian polar volcanoes, such as the permanently frozen volcanic sediments on the Kamchatka peninsula and in Antarctica. The present study shows applicability of the morphometric analysis for demonstration of the morphological similarity between the terrestrial and Martian cinder cones. In the present work, the morphometric analysis of young Martian landforms is based on the assumption that the conical structures identified on digital terrain model (DTM) are volcanic cinder cones. Morphometric analysis of the studied cones showed a range of degradation. The extent of degradation may be an indicator of age based on comparison with volcanic cinder cones on Earth. A morphometric analysis of potentially young volcanic cones in the North Polar Region of Mars was performed to estimate their relative age. The 14 potential cinder cones were identified using the DTM provided by Mars Express High Resolution Stereo Camera (HRSC), allowing for the basic morphometric calculations. The majority of the cinder cones are localized in the Chasma Boreale region within the area 79°–81°N and 261°–295°E. The calculated morphometric parameters showed that the cone average steepness varied from 3.4° to 11.8°, cone height-to-width ratio varied from 0.025 to 0.12, and the ratio between surface and basal area of the cone varied from 1.005 to 1.131. The studied cinder cones were classified with respect to the morphometric ratios assuming that larger values correspond to the younger structures. Employing the terrestrial analogy of morphometric ratios as a proxy for relative geological age, we suggest that existing microorganisms may be found in permafrost of young Martian cinder cones.

For more than four decades, a small group of researchers has sought to find evidence of extraterrestrial intelligence in situ, by detecting microwave signals that would betray its existence. Despite the failure to find these signals so far, there is continued and even accelerated effort to press the search. Recent advances include greater emphasis on experiments at optical wavelengths, and the construction of a new radio telescope that is deliberately designed for such reconnaissance. In addition to these instrumental improvements, several strategies have been proposed that might better the chances of ‘looking in the right place, at the right time’. This review of the current state of SETI research concludes with a speculative look at the nature of the sought-for extraterrestrials, and when it is likely we might find them.

On the occasion of the 50th anniversary of the Drake formula, it appears timely to briefly review the history of Astrobiology from the origins up to the epoch of the Drake formula. After reminding the main steps of this history during Antiquity, the Middle Ages, and the Renaissance, we point out some little known or unknown studies published during the Modern and Contemporary epochs. Then we review the importance of Astrobiology and the search for life in the Universe in scientific publications during the 20th century.

The discovery of icy bodies in our Solar System has opened up the possibility that life may exist on and below their surfaces. Snow and ice are good sites for the preservation of biomarkers as they trap and preserve organic matter that is deposited onto their surfaces. Terrestrial samples of snow and ice collected from Ben Macdui in north east Scotland have been analysed for organic compounds contained within them. A range of n-alkanes and n-alkanoic acids were found in both samples. The particulate matter contained proportionally more higher weight n-alkanols than the melted water. This is because higher molecular weight molecules are less soluble in water. Therefore, the volume of snow and ice to be sampled on other icy bodies is an important factor, as many important biomarkers have high molecular weights and may not be detected in small quantities of melted water.

By investigating the survival and the biomarker detectability of a rock-inhabiting cyanobacterium, Chroococcidiopsis sp. CCMEE 029, the BIOMEX space experiment might contribute to a future exploitation of the Moon as a test-bed for key astrobiology tasks such as the testing of life-detection technologies and the study of life in space. Post-flight analyses demonstrated that the mixing of dried cells with sandstone and a lunar regolith simulant provided protection against space UV radiation. During the space exposure, dried cells not mixed with minerals were killed by 2.05 × 102 kJ m−2 of UV radiation, while cells mixed with sandstone or lunar regolith survived 1.59 × 102 and 1.79 × 102 kJ m−2, respectively. No differences in survival occurred among cells mixed and not mixed with minerals and exposed to space conditions in the dark; this finding suggests that space vacuum and 0.5 Gy of ionizing radiation did not impair the cells’ presence in space. The genomic DNA of dead cells was severely damaged but still detectable with PCR amplification of a short target, thus suggesting that short sequences should be targeted in a PCR-based approach when searching for traces of life. The enhanced stability of genomic DNA of dried cells mixed with minerals and exposed to space indicates that DNA might still be detectable after prolonged periods, possibly up to millions of years in microbes shielded by minerals. Overall, the BIOMEX results contribute to future experiments regarding the exposure of cells and their biomarkers to deep space conditions in order to further test the lithopanspermia hypothesis, the biomarker stability and the microbial endurance, with implications for planetary protection and to determine if the Moon has been contaminated during past human missions.

Globally disruptive events include asteroid/comet impacts, large igneous provinces and glaciations, all of which have been considered as contributors to mass extinctions. Understanding the overall relationship between the timings of the largest extinctions and their potential proximal causes remains one of science's great unsolved mysteries. Cycles of about 60 Myr in both fossil diversity and environmental data suggest external drivers such as the passage of the Solar System through the galactic plane. While cyclic phenomena are recognized statistically, a lack of coherent mechanisms and a failure to link key events has hampered wider acceptance of multi-million year periodicity and its relevance to earth science and evolution. The generation of a robust predictive model of timings, with a clear plausible primary mechanism, would signal a paradigm shift. Here, we present a model of the timings of globally disruptive events and a possible explanation of their ultimate cause. The proposed model is a symmetrical pattern of 63 Myr sequences around a central value, interpreted as the occurrence of events along, and parallel to, the galactic midplane. The symmetry is consistent with multiple dark matter disks, aligned parallel to the midplane. One implication of the precise pattern of timings and the underlying physical model is the ability to predict future events, such as a major extinction in 1–2 Myr.

In the early 1980s, the Sagan-Tipler debate raged regarding the interpretation of the Fermi paradox but no clear winner emerged. Sagan favoured the existence of ETI on the basis of the Copernican principle and Tipler favoured the non-existence of ETI on the basis of the Occam's razor principle. Tipler's stance was an expansion of the similar but earlier Hart declaration. However, crucial to the Tipler argument was the role played by self-replicating interstellar robot probes. Any technologically capable species will develop self-replication technology as the most economical means of exploring space and the Galaxy as a whole with minimal investment. There is no evidence of such probes in our solar system including the asteroid belt, ergo, ETI do not exist. This is a powerful and cogent argument. Counter-arguments have been weak including Sagan's sociological explanations. We present a Copernican argument that ETI do not exist – humans are developing self-replication technology today. We are developing the ability to 3D print entire robotic machines from extraterrestrial resources including electric motors and electronics as part of a general in-situ resource utilization (ISRU) capability. We have 3D-printed electric motors which can be potentially leveraged from extraterrestrial material that should be available in every star system. From a similar range of materials, we have identified a means to 3D print neural network circuitry. From our industrial ecology, self-replicating machines and indeed universal constructors are feasible. We describe in some detail how a self-replicating interstellar spacecraft may be constricted from asteroidal resources. We describe technological signatures of the processing of asteroidal material (which is expected to be common to most star systems), and the excess production of certain types of clay and other detritus materials. Self-replication technology is under development and imminent – if humans are pursuing self-replication technology, then by the Copernican principle, so would any technologically savvy species elsewhere. There is no evidence that they have.

The detection of organic molecules that are indicative of past or present biological activity within the Solar System bodies and beyond is a key research area in astrobiology. Mars is of particular interest in this regard because of evidence of a (perhaps transient) warm and wet climate in its past. To date, space missions to Mars have primarily used pyrolysis technique to extract organic compounds from the Martian regolith, but it has not enabled a clear detection of unaltered native Martian organics. The elevated temperatures required for pyrolysis extraction can cause native Martian organics to react with perchlorate salts in the regolith, possibly resulting in the chlorohydrocarbons that have been detected by mass spectrometry, a commonly used in situ technique for space applications. Supercritical carbon dioxide (SCCO2) extraction technique is a powerful alternative to pyrolysis that may be capable of extracting and delivering unaltered native organic species to an analyser. In this study, we report the SCCO2 extraction of unaltered amino acids (AAs) with simple laboratory analyses of extracts by capillary electrophoresis laser-induced fluorescence (CE/LIF) and liquid chromatography with mass spectrometry (LC/MS) techniques. The extraction efficiencies of several representative AAs using SCCO2 with small amounts of pure water (~1–5%) as a co-solvent were determined. Glass beads were used as a model substrate to examine the effects of several experimental parameters and Johnson Space Center (JSC) Mars-1A Martian regolith simulant was used to study the effect of complex matrix on extraction efficiencies. With optimized experimental conditions (75C and 5% of water), extraction efficiencies from doped JSC Mars-1A were found to be ~40% for glycine, alanine and serine and ~10% for lysine. Extraction of native organics from undoped JSC Mars-1A suggests that SCCO2/water solvent system can extract both organics extractable with pure SCCO2 and those extractable with pure water. Additionally, species not extracted by either pure SCCO2 or pure water were extracted with SCCO2/water solvent. Despite the preliminary nature of this work, it paves the path for more comprehensive extraction studies of astrobiologically relevant samples with thorough analyses of resulting extracts.

The purpose of this paper is to review two mathematical models: one for the formation of homochiral polymers from an originally chirally symmetric system; and the other, to show how, in an RNA-world scenario, RNA can simultaneously act both as information storage and a catalyst for its own production. We note the similarities and differences in chemical mechanisms present in the systems. We review these two systems, analysing steady states, interesting kinetics and the stability of symmetric solutions. In both systems we show that there are ranges of parameter values where some chains increase their own concentrations faster than others.

It is widely believed that the current DNA–RNA–protein-based life forms have evolved from preceding RNA–protein-based life forms, and these again, from mere RNA replicons. By rationale, it can be assumed that the early RNA replicons were fully heterotrophic in terms of obtaining all their building blocks from their environment. In the absence of protein catalysts, their essential life functions had to be mediated by simple functional structures and mechanisms, such as RNA secondary structures, RNA–RNA interactions and RNA-mediated catalysis, and possibly by catalytic minerals or clays. The central role of RNA catalysts in early life forms is supported by the fact that several catalytic RNAs still perform central biological functions in current life forms, and at least some of these may be derived as molecular relicts from the early RNA-based life. The RNA-catalysed metabolic reactions and molecular fossils are more conserved in the eukaryotic life forms than in the prokaryotes, suggesting that the linear eukaryote genomes may more closely resemble the structure and function of the early RNA replicons, than what do the circular prokaryote genomes. Present-day RNA viruses and viroids utilize ultimately simple life strategies, which may be similar to those used by the early RNA replicons. Thus, molecular and functional properties of viruses and viroids may be considered as examples or models of the structures and replication mechanisms, which might have been used for the replication of the early biopolymers.

Astrobiology must be seen in the context of cosmic evolution, the 13.7 billion-year master narrative of the universe. The idea of an evolving universe dates back only to the 19th century, and became a guiding principle for astronomical research only in the second half of the 20th century. The modern synthesis in evolutionary biology hastened the acceptance of the idea in its cosmic setting, as did the confirmation of the Big Bang theory for the origin of the universe. NASA programmes such as Origins incorporated it as a guiding principle. Cosmic evolution encompasses physical, biological and cultural evolution, and may result in a physical, biological or postbiological universe, each with its own implications for long-term human destiny, and each imbuing the meaning of life with different values. It has the status of an increasingly accepted worldview that is beginning to have a profound effect not only in science but also in religion and philosophy.