The European Astrobiology Network Association (EANA) coordinates and promotes astrobiology in the 17 European countries that are member of the organization. Astrobiology includes the study of the origin, evolution and distribution of life in the Universe. It is a multi-disciplinary science that encompasses the disciplines of chemistry, biology, palaeontology, geology, atmospheric physics, planetary physics and stellar physics. The open questions to be addressed and the steps ahead in cosmochemistry, star and planet formation, the chemistry of life's origin, the study of bacterial life as a reference and the search for habitats and biosignatures beyond the Earth are presented.

The anatomy of the human and other vertebrates has been well described since the days of Leonardo da Vinci and Vesalius. The causative origin of the configuration of the bones and of their shapes and forms has been addressed over the ensuing centuries by such outstanding investigators as Goethe, Von Baer, Gegenbauer, Wilhelm His and D'Arcy Thompson, who sought to apply mechanical principles to morphogenesis. However, no coherent causative model of morphogenesis has ever been presented.

This paper presents a causative model for the origin of the vertebrate skeleton, based on the premise that the body is a mosaic enlargement of self-organized patterns engrained in the membrane of the egg cell. Drawings illustrate the proposed hypothetical origin of membrane patterning and the changes in the hydrostatic equilibrium of the cytoplasm that cause topographical deformations resulting in the vertebrate body form.

Habitable planets are likely to be broadly Earth-like in composition, mass and size. Masses are likely to be within a factor of a few Earth masses – we call such planets Earth-mass planets. It is important to find such planets. Currently, we do not have sufficiently sensitive techniques to detect planets with such small masses, except in rare circumstances. It is thus necessary to model the known exoplanetary systems to see whether Earth-mass planets could be present. In particular, we need to establish whether such planets could be present in the classical habitable zone (HZ), or whether the giant planets that we know to be present have gravitationally ejected Earth-mass planets or prevented their formation. We have answered this question by applying computer models to the 152 exoplanetary systems known as of 18 April 2006 that are sufficiently well characterized for our analysis. For systems in which there is a giant planet interior to the HZ, which must have got there by migration, there are two cases considered: first, the case when the migration of the giant planet across the HZ has not ruled out the existence of an Earth-mass planet in the HZ; second, the case where it has. In the former case we have found that 60% of the 152 systems offer safe havens to Earth-mass planets across greater than 20% of the HZ width. We regard such systems as being habitable today. We have also estimated whether habitability is possible for 1000 Myr into the past (provided that this period post-dates the heavy bombardment of planets in the HZ). Of the 143 systems that are susceptible to this second analysis, we find that about 50% offer habitability sustained over 1000 Myr. If giant planets interior to the HZ rule Earth-mass planets, then 60% and 50% fall to 7% in both cases.

Careful examination of the present metabolism and in vitro selection of various catalytic RNAs strongly support the RNA world hypothesis as a crucial step of the origins and early life evolution. Small functional RNAs were exposed from 10 March 2009 to 21 January 2011 to space conditions on board the International Space Station in the EXPOSE-R mission. The aim of this study was to investigate the preservation or modification properties such as integrity of RNAs after space exposition. The exposition to the solar radiation has a strong degradation effect on the size distribution of RNA. Moreover, the comparison between the in-flight samples, exposed to the Sun and not exposed, indicates that the solar radiation degrades RNA bases.

We have used a simple camera phone to significantly improve an ‘exploration system’ for astrobiology and geology. This camera phone will make it much easier to develop and test computer-vision algorithms for future planetary exploration. We envision that the ‘Astrobiology Phone-cam’ exploration system can be fruitfully used in other problem domains as well.

I outline a general thermodynamic condition for the earliest steps in the origin of life based on fluctuation theorems developed in the last two decades. I argue that the exponentially developing loop of asymmetric autocatalysis and thermodynamic tail-wind condition (TTC) in the prebiotic clutter was a key to a particular trajectory of decluttering via a sequence of early symmetry breaking events. Such decluttering was bound to result, most prominently, in homochiral amino acids and homochiral sugars composing nucleotides as the TTC exponentially favoured asymmetric autocatalytic processes over catalytic and symmetric autocatalytic processes in the clutter. I describe the loop's structure, including its chemical and physical properties, and explain that the TTC/asymmetric autocatalysis loop intersected with multiple chemical, geological and climatological feedback loops, thus providing conditions for the propagation of living systems as we know them.

Tagish Lake meteorite, which fell in January 2000 in Canada, has provided a sample of pristine cosmic materials for laboratory studies. It is made up of loosely formed aggregates, making it one of the most friable carbonaceous chondrites. Its complex structure is composed of plaquettes of crystalized minerals, hexagon-shaped metals, chondrules and granules, all of which are embedded in a matrix of fine grains and fibril-like materials. Those components with sizes larger than 250 nm in diameter are affected to varying degrees by hydrothermal reactions, whereas the majority of smaller bodies (<350 nm in diameter) appear unscathed despite severe aqueous alterations on the parent body. A high population of granules (100–300 nm in diameter) consist of a wall (20–40 nm in thickness) and a larger core; the former is rich in organic elements, such as carbon, oxygen and sulfur, and the core contains Ni-Fe-Mg rich silicates. The organic matter has aromatic and aliphatic characteristics, and such evidence suggests that the granules may be the carriers of large organic species with distinct astrobiological implications.

Planetary habitability may be affected by exposure to γ radiation from supernovae (SNe). Records of Earth history during the late Quaternary Period (40 000 years to present) allow testing for specific SN γ radiation effects. SNe include Type Ia white dwarf explosions, Type Ib, c and II core collapses, and many γ burst objects. Surveys of galactic SNe remnants offer a nearly complete accounting for this time and including SN distances and ages. Terrestrial changes in records of the cosmogenic isotope 14C are here compared to SN-predicted changes. SN γ emission occurs mainly within 3 years; average per-event total emissions of 4 × 1049 erg are used for comparison of close events There are 18 SNe ≤ 1.5 kpc, and brief 14C anomalies are reported for eight of the closest. Four are notable (BP is year before 1950 CE): the older Vela SNR and an abrupt 30‰ del 14C rise at 12 740 BP; S165 and a 20‰ rise at 7431 BP; Vela Jr. and a 14‰ rise at 2765 BP; and HB9 and a 9‰ rise at 5372 BP. Rapid-increase anomalies in 14C production have been attributed to cosmic rays from exceptionally large solar flares. However, the proximity and ages of these SNe, the probable size and duration of their γ emissions, the predicted effects on 14C, and the agreement with 14C records together support SNe causation. Also, the supposed solar-caused 14C anomalies at CE 774 and 993 may instead have been caused by the SNe associated with the G190.9-2.2 and G347.3-00.5 remnants. Both are of appropriate age and distance.

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.

The spontaneous formation of catalytic polypeptides of various lengths in a primordial ocean endowed with a source of amino acids from micrometeorites was investigated and found to be sufficient to induce the transformation of potential substrates under the assumption of a high propensity of the environment to catalyse the formation of the peptide bond. This work aims to include in this picture the effect of autocatalysis, i.e. the ability of a polypeptide with a specific length to promote the formation of the peptide bond. Once the formation of an autocatalytic species is attained, the concentrations of the polypeptides, substrates and products of reaction exhibit a time-dependent rate of formation and undergo a catastrophic change. While in the absence of autocatalysis the concentrations of polypeptides are stationary and the formation of reaction products is limited by the proper frequency λ, autocatalysis induces a steady growth of the concentrations of polypeptides and a 100 − 105-fold increase of reaction products at t = ω−1<0.46 Gyr, with a subsequent linear growth in time according to the law u/z0 = 1+s(ω−1+t)/z0, provided the autocatalytic species be active with length fewer than 70 amino acid units. A relationship was found between the catalytic ability of the environment (expressed by the ratio η/ηh of the rate coefficient for peptide bond formation to the corresponding rate coefficient for hydrolysis) and the time of the sharp increase of the concentration of both the polypeptides and their products of transformation. Although the formation of autocatalytic polypeptides is able to rapidly induce a sharp increase in the concentration of both polypeptides and their products of transformation, the crucial formation of the first autocatalytic polypeptides relies on the ability of the environment to promote the formation of the peptide bond. The value of the ratio η/ηh, constrained by the available time for chemical evolution to values bordering the catalytic activity of present-day enzymes, suggests that the correlation between the presence of water and the formation of a complex chemistry should be taken with caution.

Students in an introductory undergraduate Astrobiology course were given a pre/post-test based on the Drake Equation in an attempt to measure changes in their perceptions regarding the prevalence of life in the Galaxy after taking the course. The results indicated that, after taking the course, the students were considerably more optimistic, by a 2 to 1 margin or more, about the prospect of habitable planets, the origin of life, and the evolution of intelligence in other planetary systems. The results suggest that, while it may not be the explicit goal of an astrobiology course to change student beliefs about the abundance or rarity of extraterrestrial life, such changes in opinion can and do occur.

The origin of life from inanimate matter is still an open question, and our knowledge is still very limited. In this sense, prebiotic chemistry seeks to study and understand how chemical reactions may have contributed to the origin of life. Minerals are of great relevance to prebiotic chemistry, as they may have preconcentrated precursors of biomolecules or biomolecules from diluted solutions, provided protection for biomolecules against UV radiation and hydrolysis, catalysing their reactions and played the role of a primitive genetic code. Montmorillonite, a prebiotic mineral, was shown to be able to adsorb adenine and later also histidine. In addition, histidine adsorption did not displace adenine from the montmorillonite. Kinetic experiments showed that using a whole period of time (7 days) it was not possible to adjust the data to any mathematical kinetic model. Thus, the data were separated into four different adsorption ranges: range 1 (0–60 min), range 2 (60–4320 min), range 3 (4320–7200 min) and range 4 (7200–10 080 min). Range 1 showed adsorption that was too fast, meaning no variations in the adsorption data, and the data of range 3 did not fit in any model used in this work. Thus, range 2 (60–4320 min) and range 4 (7200–10 080 min) were analysed. The adsorption kinetics of histidine adsorption indicated two reaction steps, a quick step (60–4320 min), following the pseudo-first-order model, followed by a slower step (7200–10 080 min) of the pseudo-second order. With these results, isotherms were constructed with times of 1 h and 7 days. The results of the quick step (1 h) showed a reaction that was not thermodynamically favoured. For this time range, Gibbs energy values obtained ranged between 5 and 10 kJ mol−1 at temperatures of 20, 35 and 50°C, and the adsorption occurred due to the balance shift of increase in histidine concentrations. The isotherms of the slow step (7 days) presented negative values, showing a more favourable reaction with Gibbs energy values ranging between −5 and −11 kJ mol−1. The mathematical modelling of the data indicates that seawater ions are crucial in the adsorption process. Thus, the study provided essential information for prebiotic chemistry, showing that time and the reaction medium should always be taken into account.

A high level of stellar activity in the form of frequent flaring and frequent mass ejections can lead to the total loss of exoplanetary atmospheres due to evaporation and erosion. Simulations have shown such scenarii for close-in exoplanets orbiting M-stars. Information on stellar flaring activity is accessible more easily than information on stellar mass ejections, simply due to the difference in detection. In the National Aeronautics and Space Administration/Far Ultraviolet Spectroscopic Explorer spectra of the dM star AD Leonis we find an interesting event lasting for only one spectrum. The first component of the OVI (103.19 nm, 103.76 nm) duplet shows an enhancement of the blue wing, shifted by about 90 km s−1. This event occurred one spectrum after a flare. We discuss several solar/stellar phenomena that might produce such a spectral feature and could therefore explain this event.

The Fermi paradox has given rise to various attempts to explain why no evidence of extraterrestrial civilizations was found so far on Earth and in our Solar System. Here, we present a dynamical model for the development of such civilizations, which accounts for self-destruction, colonization and astrophysical destruction mechanisms of civilizations including gamma-ray bursts, type Ia and type II supernovae as well as radiation from the supermassive black hole. We adopt conservative estimates regarding the efficiency of such processes and find that astrophysical effects can influence the development of intelligent civilizations and change the number of systems with such civilizations by roughly a factor of $2$; potentially more if the feedback is enhanced. Our results show that non-equilibrium evolution allows for solutions in-between extreme cases such as ‘rare Earth’ or extreme colonization, including scenarios with civilization fractions between $10^{-2}$ and $10^{-7}$. These would imply still potentially large distances to the next such civilizations, particularly when persistence phenomena are being considered. As previous studies, we confirm that the main uncertainties are due to the lifetime of civilizations as well as the assumed rate of colonization. For SETI-like studies, we believe that unbiased searches are needed considering both the possibilities that the next civilizations are nearby or potentially very far away.

Bioaerosol particles in the stratosphere are topics of interest for aerobiological and astrobiological studies. Although various studies have succeeded in sampling bioaerosol particles in the stratosphere, limited research has been conducted to evaluate how and why these bioaerosol particles can lift up to as high as the stratospheric level. This study tested different driving forces acting on particles in the stratosphere in order to simulate the motion of particles with various bioaerosol characteristics. The findings show that small pollen-sized particles can scarcely levitate in the stratosphere, although spore-sized and dust particles attached to microorganisms such as bacteria or fungus might be able to do so.

Previous exploration missions have revealed Mars as a potential candidate for the existence of extraterrestrial life. If life could have existed beneath the Martian subsurface, biosignatures would have been preserved in iron-rich minerals. Prior investigations of terrestrial biosignatures and metabolic processes of geological analogues would be beneficial for identifying past metabolic processes on Mars, particularly morphological and chemical signatures indicative of past life, where biological components could potentially be denatured following continued exposure to extreme conditions. The objective of the research was to find potential implications for Martian subsurface life by characterizing morphological, mineralogical and microbial signatures of hematite deposits, both hematite rock and related soil samples, collected from Highland Complex of Sri Lanka. Rock samples examined through scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy. Analysis showed globular and spherical growth layers nucleated by bacteria. EDX results showed a higher iron to oxygen ratio in nuclei colonies compared to growth layers, which indicated a compositional variation due to microbial interaction. X-ray diffraction analysis of the hematite samples revealed variations in chemical composition along the vertical soil profile, with the top surface soil layer being particularly enriched with Fe2O3, suggesting internal dissolution of hematite through weathering. Furthermore, inductively coupled plasma-mass spectrometry analyses carried out on both rock and soil samples showed a possible indication of microbially induced mineral-weathering, particularly release of trapped trace metals in the parent rock. Microbial diversity analysis using 16S rRNA gene sequencing revealed that the rock sample was dominated by Actinobacteria and Proteobacteria, specifically, members of iron-metabolizing bacterial genera, including Mycobacterium, Arthrobacter, Amycolatopsis, Nocardia and Pedomicrobium. These results suggest that morphological and biogeochemical clues derived from studying the role of bacterial activity in hematite weathering and precipitation processes can be implemented as potential comparative tools to interpret similar processes that could have occurred on early Mars.

The modification of minerals with metals can promote changes in their surface and, consequently, in their physicochemical properties. Minerals could have played an important role in the origin of life as they can protect molecules against degradation by radiation and hydrolysis, pre-concentrate molecules from dilute solutions and catalyse the formation of polymers. Thus, the current work studied the modification of montmorillonite with Cu2+ and Fe3+ ions. These modified montmorillonites were used to study the interaction with adenine dissolved in distilled water and artificial seawater 4.0 Gy (Gy = billion years ago). The most important result of this work is that the adsorption of adenine onto modified montmorillonites is a complex interaction among adenine, salts in seawater and Cu2+/Fe3+-montmorillonite (Cu2+/Fe3+-Mont) . The adsorption of Cu2+ and Fe3+ onto montmorillonite decreased its surface area and pore volume. The Sips isotherm model showed the best fit of the data and n values indicate that the adenine adsorption process was homogeneous. The highest adenine adsorption was obtained in artificial seawater 4.0 Gy onto Fe3+-Mont at 60°C and the lowest in distilled water or artificial seawater 4.0 Gy onto montmorillonite [montmorillonite washed with distilled water (Mont-STD)] at 60°C. Adenine adsorption onto Mont-STD/montmorillonite modified with 500 ml of 0.1 mol l−1 of CuCl2 and Fe3+-Mont was an exothermic process and an endothermic process, respectively. For all adsorptions ΔG was negative. The adsorption of adenine onto Fe3+-Mont was ruled out by entropy and the other samples by enthalpy and entropy, being a major contribution for Gibbs free energy from enthalpy. The Fourier transform-infrared data indicate that the interaction of adenine with minerals may occur through the NH2 functional group.

Suppose that advanced civilizations, separated by a cosmological distance and time, wish to maximize their access to cosmic resources by rapidly expanding into the universe. How does the presence of one limit the expansionistic ambitions of another, and what sort of boundary forms between their expanding domains? We describe a general scenario for any expansion speed, separation distance and time. We then specialize to a question of particular interest: What are the future prospects for a young and ambitious civilization if they can observe the presence of another at a cosmological distance? We treat cases involving the observation of one or two expanding domains. In the single-observation case, we find that almost any plausible detection will limit one's future cosmic expansion to some extent. Also, practical technological limits to expansion speed (well below the speed of light) play an interesting role. If a domain is visible at the time one embarks on cosmic expansion, higher practical limits to expansion speed are beneficial only up to a certain point. Beyond this point, a higher speed limit means that gains in the ability to expand are more than offset by the first-mover advantage of the observed domain. In the case of two visible domains, it is possible to be ‘trapped’ by them if the practical speed limit is high enough and their angular separation in the sky is large enough, i.e. one's expansion in any direction will terminate at a boundary with the two visible civilizations. Detection at an extreme cosmological distance has surprisingly little mitigating effect on our conclusions.

Exporting terrestrial life out of the Solar System requires a process that both embeds microbes in boulders and ejects those boulders out of the Solar System. We explore the possibility that Earthgrazing long-period comets (LPCs) and interstellar objects (ISOs) could export life from Earth by collecting microbes from the atmosphere and receiving a gravitational slingshot effect from the Earth. We estimate the total number of exportation events over the lifetime of the Earth to be ~1–10 for LPCs and ~1–50 for ISOs. If life existed above an altitude of 100 km, then the number is dramatically increased up to ~105 exportation events over Earth's lifetime.