We address a recently posed question: ‘Why Do So Many Astronomy (and Astrobiology) Discoveries Fail to Live Up to the Hype?’ We expand it to cover hype within science in general. Our answer relies on working definitions of hype and skin in the game, as applied to research science, and a game theory model for the stability of cooperative science. Low skin in the game allows internal feedbacks, within the research science community, to initiate increased hype and a drift toward structural instability. The instability leads to the deterioration of cooperative equilibria, which further enhances hype. Along the drift, the number of results hyped as breakthroughs will increase and more claims will fail to live up to the hype. This can lead to the public perception that science is moving backwards and a shift in the perception of what scientists, and science, values. Although a hype instability can be initiated by external nudges, a bigger role is played by the internal dynamics of the system, i.e. the collective of working scientists. Corrections for a drift toward instability should, likewise, focus on internal structure. Proposed external shifts on how research is disseminated will add restrictions to a system that can do more harm than good.

As soon as samples collected from Mars will be brought back to Earth, the samples will be placed inside a receiving facility to check for the presence of life. There is a large number of approaches that were proposed on the techniques to be used to investigate the presence of life and any biological risk in the returned samples. Another interesting approach was reported by Kminek in which suggestions were provided on how to organize the sample analysis sequence within the facility. Finally, another study suggested a long list of techniques capable of measuring biological signatures based on their general characteristics: global, morphological, mineralogical, organic, molecular and biochemical, isotopic analysis. Despite the effort of the cited studies, there is still the need of a critical approach to make an actual comparison between the techniques, with the aim to find a ranking. In this work, we focused on the construction of a correlation matrix with which to correlate biosignatures to analytical techniques. It is known that a number of techniques can detect biological signatures and, at the same time, each technique can be applied to multiple biological signatures. Using this method, it is possible to summarize all this information to be easily consulted, but also to define in a quantitative way how strong each correlation is.

In this paper we consider a scenario in which Carl Sagan's Copernican principle is more likely than its negation. Thus, assuming that the existence of an extraterrestrial intelligence (ETI) is reasonably likely, the paper considers the possibility of an ETI that is unable to recognize humans as intelligent beings. The paper presents the rationale for such an assumption. It also discusses the possible consequences for humanity of such a scenario. In this paper, we argue why the scenario under discussion is actually more positive for humanity than a scenario in which ETI would be capable of recognizing humanity as an intelligent species. We also point to feminist approaches to SETI issues exposing the role played by the specific evolutionary and developmental context of potential ETI.

Advanced extraterrestrial civilizations may produce observable technosignatures when they migrate inside their planetary systems and to other planetary systems. Collectively, the search for technosignatures produced by migrating extraterrestrial civilizations can be described as the search for migrating extraterrestrial intelligence (SMETI). I propose that extraterrestrial civilizations may use free-floating planets as interstellar transportation to reach, explore and colonize planetary systems. I propose possible technosignatures and artefacts that may be produced by extraterrestrial civilizations using free-floating planets for interstellar migration and interstellar colonization, as well as strategies for the search for their technosignatures and artefacts. I discuss technosignatures that may be produced by extraterrestrial civilizations using other methods of interstellar migration and colonization. As an example, I discuss the star GJ 433, which experienced a close flyby a few thousand years ago. I divide possible technosignatures of migrating civilizations into groups to highlight similarities and differences among technosignatures produced by civilizations using different methods of migration and interstellar colonization. It follows from the comparison, for example, that interstellar migration using flybys of stars can blend with interstellar migration using free-floating planets.

The experimental study aimed to select the spectrometric results of the solar flare that meet the mathematical conditions for integration, to measure the power of this integrated flux, and to test the integrated power, whether it is able to form a peptide bond between two molecules of selected amino acids on the Earth's surface. Results show that the radiation power of the X17 solar flare scanned by the SOLSTICE and SIM spectrometers aboard the NASA SORCE spacecraft, when used for experimental irradiance of the same parameters, is sufficient to form methionine, alanine, glutamine and proline dipeptides in aqueous solution with pyrophosphate or carbonyl sulphide at laboratory temperature. The experiments, with their successful outcome, provide insight into the biological significance of the narrowband solar flare anchored in the broadband UV solar radiation.

Solutions to the Fermi paradox either deny the existence of extraterrestrials or offer alternative reasons to explain the non-occurrence of a first contact. While the latter, more optimistic approaches generally assume the existence of extraterrestrials, they simultaneously hint to limited future detectability. If solutions to the Fermi paradox are accepted as true, they must be evaluated in terms of how they affect the likelihood of success of future SETI efforts. Some solutions may lead to the so-called Fermi constraint: in order to explain why there has not been any contact so far, optimistic solutions to the Fermi paradox have to accept assumptions that, if the solution is assumed to be correct, indicate a very low probability of future contact. In other words: they are not here, and that is why they may never appear.

Mars analogue environments are some of the most extreme locations on Earth. Their unique combination of multiples extremes (e.g. high salinity, anoxia and low nutrient availability) make them valuable sources for finding new polyextremophilic microbes, and for exploring the limits of life. Mars, especially at its surface, is still considered to be very hostile to life but it probably possesses geological subsurface niches where the occurrence of (polyextremophilic) life is conceivable. Despite their well-recognized relevance, current knowledge on the capability of (facultative) anaerobic microbes to withstand extraterrestrial/Martian conditions, either as single strains or in communities, is still very sparse. Therefore, space experiments simulating the Martian environmental conditions by using space as a tool for astrobiological research are needed to substantiate the hypotheses of habitability of Mars. Addressing this knowledge gap is one of the main goals of the project MEXEM (Mars EXposed Extremophiles Mixture), where selected model organisms will be subjected to space for a period of 3 months. These experiments will take place on the Exobiology facility (currently under development and implementation), located outside the International Space Station. Such space experiments require a series of preliminary tests and ground data collection for the selected microbial strains. Here, we report on the survivability of Salinisphaera shabanensis and Buttiauxella sp. MASE-IM-9 after exposure to Mars-relevant stress factors (such as desiccation and ultraviolet (UV) radiation under anoxia). Both organisms showed survival after anoxic desiccation for up to 3 months but this could be further extended (nearly doubled) by adding artificial Mars regolith (MGS-1S; 0.5% wt/v) and sucrose (0.1 M). Survival after desiccation was also observed when both organisms were mixed before treatment. Mixing also positively influenced survival after exposure to polychromatic Mars-like UV radiation (200–400 nm) up to 12 kJ m−2, both in suspension and in a desiccated form.

Astrobiology Graduates in Europe (AbGradE, pronounced ab-grad-ee) is an association of early-career scientists working in fields relevant to astrobiological research. Conceptualized in 2013, it was initially designed as a mini-conference or workshop dedicated to early-career researchers, providing a friendly environment where early-career minds would be able to present their research without being intimidated by the possibility of facing a more traditional audience, composed mainly of senior scientists. Within the last couple of years, AbGradE became the first point of call for European, but also for an increasing number of non-European, early-career astrobiologists. This article aims to present how AbGradE has evolved over the years (in its structure and in its way of organizing events), how it has adapted with the COVID-19 pandemic, and what future developments are considered.

The biotic scenario of the selection of biological homochirality is one of the most interesting applications of computer modelling to astrobiology. These scenarios have been studied for more than 70 years, yet there are plenty of studies to better assess them, in particular in the development of models of the selective extinction process. In this paper, we review former studies performed by biology-grounded models of this process and present a new class of computer programs: they further demonstrate the complexity of the selective extinction dynamics and the role played into it by non-trivial chemical-physical concepts. Indeed, the results display large and persistent differences between the populations of the two different chiral types, made possible by the freedom of individual populations to fluctuate wildly while the total population is stabilized by the limited availability of chemical energy. Such strong differences ultimately lead to the selective extinction of one of the two types. This way, computer simulations provide increasing evidence in favour of the biotic scenario.

Xanthoria parietina is a widespread foliose lichen growing on barks and rocks showing a broad spectrum of tolerance to air pollutants such as NOX and heavy metals, and resistance to UV-radiation because of the screening properties provided by the secondary metabolite parietin. The aim of this study was to evaluate the ability of this lichen species to survive in the following simulated space conditions, UV-radiation in N2 atmosphere and UV-radiation in vacuum. The efficiency of the photosynthetic apparatus was used as an indicator of vitality, and was expressed in terms of chlorophyll a fluorescence (FV/FM) and Normalized Difference Vegetation Index (NDVI), which were measured within 72 h from the exposure. Additionally, during the irradiation, the IR reflectance spectrum of the lichen was monitored in situ to assess changes in spectral bands. The results showed significant differences in physiological recovery trends between the treatments, highlighting that UV-radiation in vacuum causes stronger effects on FV/FM values. The IR analysis revealed several spectral band changes in the fingerprint region. The most visible variation was the 5200 cm−1 water band that disappeared in the overtone region. Nevertheless, X. parietina was able to survive UV-radiation in N2 atmosphere and in vacuum, and for this reason it may be considered a candidate for further evaluations on its survival capacity in extreme conditions.

Conventionally, intelligence is seen as a property of individuals. However, it is also known to be a property of collectives. Here, we broaden the idea of intelligence as a collective property and extend it to the planetary scale. We consider the ways in which the appearance of technological intelligence may represent a kind of planetary scale transition, and thus might be seen not as something which happens on a planet but to a planet, much as some models propose the origin of life itself was a planetary phenomenon. Our approach follows the recognition among researchers that the correct scale to understand key aspects of life and its evolution is planetary, as opposed to the more traditional focus on individual species. We explore ways in which the concept may prove useful for three distinct domains: Earth Systems and Exoplanet studies; Anthropocene and Sustainability studies; and the study of Technosignatures and the Search for Extraterrestrial Intelligence (SETI). We argue that explorations of planetary intelligence, defined as the acquisition and application of collective knowledge operating at a planetary scale and integrated into the function of coupled planetary systems, can prove a useful framework for understanding possible paths of the long-term evolution of inhabited planets including future trajectories for life on Earth and predicting features of intelligentially steered planetary evolution on other worlds.

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; and

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; and

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.

In this work, we address the difficulty of reliably identifying traces of life on Mars. Several independent lines of evidence are required to build a compelling body of proof. In particular, we underline the importance of correctly interpreting the geological and mineralogical context of the sites to be explored for the presence of biosignatures. We use as examples to illustrate this, ALH84001 (where knowledge of the geological context was very limited) and other terrestrial deposits, for which this could be properly established. We also discuss promising locations and formations to be explored by ongoing and future rover missions, including Oxia Planum, which, dated at 4.0 Ga, is the most ancient Mars location targeted for investigation yet.

Mars lacks a substantial magnetic field; as a result, the solar wind ablates the Martian atmosphere, and cosmic rays from solar flares make the surface uninhabitable. Therefore, any terraforming attempt will require an artificial Martian magnetic shield. The fundamental challenge of building an artificial magnetosphere is to condense planetary-scale currents and magnetic fields down to the smallest mass possible. Superconducting electromagnets offer a way to do this. However, the underlying physics of superconductors and electromagnets limits this concentration. Based upon these fundamental limitations, we show that the amount of superconducting material is proportional to $B_{\rm c}^{-2}a^{-3}$, where Bc is the critical magnetic field for the superconductor and a is the loop radius of a solenoid. Since Bc is set by fundamental physics, the only truly adjustable parameter for the design is the loop radius; a larger loop radius minimizes the amount of superconducting material required. This non-intuitive result means that the ‘intuitive’ strategy of building a compact electromagnet and placing it between Mars and the Sun at the first Lagrange point is unfeasible. Considering reasonable limits on Bc, the smallest possible loop radius is ~10 km, and the magnetic shield would have a mass of ~ 1019 g. Most high-temperature superconductors are constructed of rare elements; given solar system abundances, building a superconductor with ~ 1019 g would require mining a solar system body with several times 1025 g; this is approximately 10% of Mars. We find that the most feasible design is to encircle Mars with a superconducting wire with a loop radius of ~3400 km. The resulting wire diameter can be as small as ~5 cm. With this design, the magnetic shield would have a mass of ~ 1012 g and would require mining ~ 1018 g, or only 0.1% of Olympus Mons.

The unique environment of space is characterized by several stress factors, including intense radiation, microgravity, high vacuum and extreme temperatures, among others. These stress conditions individually or in-combination influence genetics and gene regulation and bring potential evolutionary changes in organisms that would not occur under the Earth's gravity regime (1 × g). Thus, space can be explored to support the emergence of new varieties of microbes and plants, that when selected for, can exhibit increased growth and yield, improved resistance to pathogens, enhanced tolerance to drought, low nutrient and disease, produce new metabolites and others. These properties may be more difficult to achieve using other approaches under 1 × g. This review provides an overview of the space microgravity and ionizing radiation conditions that significantly influence organisms. Changes in the genomics, physiology, phenotype, growth and metabolites of organisms in real and simulated microgravity and radiation conditions are illustrated. Results of space biological experiments show that the space environment has significant scientific, technological and commercial potential. Combined these potentials can help address the future of life on Earth, part of goal e of astrobiology.