The extremotolerant bacterium Deinococcus radiodurans is used as a model to explore the limits of life on Earth and beyond. In experiments performed in an ultra-high vacuum chamber with a vacuum ultraviolet (VUV) synchrotron beamline, this microorganism was exposed to conditions present on an extraterrestrial environment unprotected by an atmosphere, such as outside a spacecraft or on an asteroid, relevant in the context of planetary protection and panspermia hypothesis. Different methods were used to obtain the biologically relevant information from this investigation. Counting of colony forming units, the traditional approach for viability assessment, is limited to measuring the survival of the cells. For a more in-depth study of damage mechanisms at subcellular levels, specific molecular probes (propidium iodide and dihydrorhodamine 123) were applied and whole populations could be analysed, cell by cell, by flow cytometry. VUV radiation caused a substantial loss of viability, though only a fraction of the cells presented membrane damages even at the largest tested fluences. Additionally, intracellular oxidative stress was also detected upon exposure. These results point to significant VUV inactivating effects extending beyond the cells' outermost structures, in contrast to a more superficial role that could be expected due to the highly interacting nature of this radiation range. Nevertheless, it was observed that microscopic-level shading sufficed to allow the persistence of a small surviving subpopulation for the longer expositions. This study contributes to unveiling the response of biological systems under space conditions, assessing not just cell viability but also the mechanisms that lead to inactivation.

Investigations into the existence of life in other parts of the cosmos find strong parallels with studies of the origin and evolution of life on our own planet. In this way, astrobiology and paleobiology are married by their common interest in disentangling the interconnections between life and the surrounding environment. In this way, a cross-point of both sciences is paleometry, which involves a myriad of imaging and geochemical techniques, usually non-destructive, applied to the investigation of the fossil record. In the last decades, paleometry has benefited from an unprecedented technological improvement, thus solving old questions and raising new ones. This advance has been paralleled by conceptual approaches and discoveries fuelled by technological evolution in astrobiological research. In this context, we present some new data and review recent advances on the employment of paleometry to investigations on paleobiology and astrobiology in Brazil in areas such biosignatures in Ediacaran microbial mats, biogenicity tests on enigmatic Ediacaran structures, research on Ediacaran metazoan biomineralization, fossil preservation in Cretaceous insects and fish, and finally the experimental study on the decay of fish to test the effect of distinct types of sediment on soft-tissue preservation, as well as the effects of early diagenesis on fish bone preservation.

Martian meteorites have valuable information about past geological processes on Mars. In this particular case, the sample used was the Martian meteorite Northwest Africa (NWA) 7397. The main objective was to conduct preliminary analyses of the sample that was able to provide mineralogical characteristics in a non-destructive way. These meteorite NWA 7397 analyses were performed using two analytical techniques, μRaman and μXRF. Through the techniques used it was possible to suggest the presence of chromite, ilmenite, magnetite and forsterite minerals. These minerals seem to have a correspondence to one another in relation to the process that formed them. Thus, the information generated by these analytical techniques can contribute significantly by providing information on the history of Mars in order to have relevance to the areas of Astrobiology and Planetary Sciences.

The establishment of cosmology as a science provides a parallel to the building-up of the scientific status of astrobiology. The rise of astrobiological studies is explicitly based on a transdisciplinary approach that reminds of the Copernican Revolution, which eroded the basis of a closed Aristotelian worldview and reinforced the notion that the frontiers between disciplines are artificial. Given the intrinsic complexity of the astrobiological studies, with its multifactorial evidences and theoretical/experimental approaches, multi- and interdisciplinary perspectives are mandatory. Insulated expertise cannot grasp the vastness of the astrobiological issues. This need for integration among disciplines and research areas is antagonistic to excessive specialization and compartmentalization, allowing astrobiology to be qualified as a truly transdisciplinary enterprise. The present paper discusses the scientific status of astrobiological studies, based on the view that every kind of life, Earth-based or not, should be considered in a cosmic context. A confluence between ‘astro’ and ‘bio’ seeks the understanding of life as an emerging phenomenon in the universe. Thus, a new epistemological niche is opened, pointing to the development of a pluralistic vision for the philosophy of astrobiology.

The International Astronomical Union's Commission 51 was established in 1982 as\break “Bioastronomy: Search for Extraterrestrial Life”. As the interests of Commission members expanded to include all aspects of the study of the origin, evolution, and distribution of life in the universe, C51 was renamed simply “Bioastronomy” in 2006. Thus, the term “bioastronomy” became for the Commission essentially synonymous with the NASA-coined term “astrobiology“. Since the latter term has been adopted by many scientific societies around the world with similar interests, under the new Division and Commission structure of the IAU the Commission has been again renamed and is now Commission F-3 “Astrobiology”.

The Earth is constantly struck by radiation coming from the interstellar medium. The very low energy end of the spectrum is shielded by the geomagnetic field but charged particles with energies higher than the geomagnetic cutoff will penetrate the atmosphere and are likely to interact, giving rise to secondary particles. Some astrophysical events, such as γ-ray bursts and supernovae, when happening at short distances, may affect the planet's biosphere, due to the temporary enhanced radiation flux. Muons are abundantly produced by high-energy cosmic rays in the Earth's atmosphere. These particles, due to their low cross-section, are able to penetrate deep both underground and underwater, with the possibility of affecting biological niches normally considered shielded from radiation. We investigate the interaction of muons produced by high-energy cosmic rays on the Earth's atmosphere using the Geant4 toolkit. We analyse its penetration power in water and crust and also the interaction effects within bacteria-like material according to the particle type and energy, and noticed the possibility of off-track damage due to secondary particles.

Astrobiology is a relatively recent scientific field that seeks to understand the origin and dynamics of life in the Universe. Several hypotheses have been proposed to explain life in the cosmic context throughout human history, but only now, technology has allowed many of them to be tested. Laboratory experiments have been able to show how chemical elements essential to life, such as carbon, nitrogen, oxygen and hydrogen combine in biologically important compounds. Interestingly, these compounds are ubiquitous. How these compounds were combined to the point of originating cells and complex organisms is still to be unveiled by science. However, our 4.5 billion years old Solar system appeared in a 10 billion years old Universe. Thus, simple cells such as micro-organisms may have had time to form in planets older than ours or in other suitable places in the Universe. One hypothesis related to the appearance of life on Earth is called panspermia, which predicts that microbial life could have been formed in the Universe billions of years ago, travelling between planets, and inseminating units of life that could have become more complex in habitable planets such as Earth. A project designed to test the viability of extremophile micro-organisms exposed to simulated extraterrestrial environments is in progress at the Carlos Chagas Filho Institute of Biophysics (UFRJ, Brazil) to test whether microbial life could withstand inhospitable environments. Radiation-resistant (known or novel ones) micro-organisms collected from extreme terrestrial environments have been exposed (at synchrotron accelerators) to intense radiation sources simulating Solar radiation, capable of emitting radiation in a few hours equivalent to many years of accumulated doses. The results obtained in these experiments reveal an interesting possibility of the existence of microbial life beyond Earth.

With the possible exception of meteor impacts, high-energy astrophysical events such as supernovae, gamma-ray bursts (GRB) and flares are usually not taken into account for biological and evolutionary studies due to their low rates of occurrence. We show that a class of these events may occur at distances and time scales in which their biological effects are non-negligible, maybe more frequent than the impacts of large asteroids. We review the effects of four transient astrophysical sources of ionizing radiation on biospheres – stellar flares, giant flares from soft gamma repeaters (SGR), supernovae and GRB. The main damaging features of them are briefly discussed and illustrated. We point out some open problems and ongoing work.

We present a summary of a three-year academic research proposal drafted during the Sao Paulo Advanced School of Astrobiology (SPASA) to prepare for upcoming observations of tidally locked planets orbiting M-dwarf stars. The primary experimental goal of the suggested research is to expose extremophiles from analogue environments to a modified space simulation chamber reproducing the environmental parameters of a tidally locked planet in the habitable zone of a late-type star. Here we focus on a description of the astronomical analysis used to define the parameters for this climate simulation.

This review reports the Brazilian history in astrobiology, as well as the first delineation of a vision of the future development of the field in the country, exploring its abundant biodiversity, highly capable human resources and state-of-the-art facilities, reflecting the last few years of stable governmental investments in science, technology and education, all conditions providing good perspectives on continued and steadily growing funding for astrobiology-related research. Brazil is growing steadily and fast in terms of its worldwide economic power, an effect being reflected in different areas of the Brazilian society, including industry, technology, education, social care and scientific production. In the field of astrobiology, the country has had some important landmarks, more intensely after the First Brazilian Workshop on Astrobiology in 2006. The history of astrobiology in Brazil, however, is not so recent and had its first occurrence in 1958. Since then, researchers carried out many individual initiatives across the country in astrobiology-related fields, resulting in an ever growing and expressive scientific production. The number of publications, including articles and theses, has particularly increased in the last decade, but still counting with the effort of researchers working individually. That scenario started to change in 2009, when a formal group of Brazilian researchers working with astrobiology was organized, aiming at congregating the scientific community interested in the subject and to promote the necessary interactions to achieve a multidisciplinary work, receiving facilities and funding from the University de Sao Paulo and other funding agencies.

In this paper we present a unified, quantitative synthesis of analytical and numerical calculations of the effects that could be caused on Earth by a gamma-ray burst (GRB), considering atmospheric and biological implications. The main consequences of the illumination by a GRB are grouped into four distinct classes and analysed separately, namely: direct γ flash, UV flash, O3 layer depletion and cosmic rays. The effectiveness of each of these classes is compared and distances for significant biological damage are given for each one. We find that the first three effects have the potential to cause global environmental changes and biospheric damage, even if the source is located at galactic distances or even farther afield (up to 150 kpc, where 1 parsec=3.09×1016 m, about five times the Galactic diameter of 30 kpc). Instead, cosmic rays would only be a serious threat for close sources (of the order of a few parsecs).

As a concrete application from a well-recorded event, the effects on the biosphere of an event identical to the giant flare of SGR1806-20 on 27 December 2004 have been calculated. In spite of not belonging to the so-called ‘classical’ GRBs, most of the parameters of this recent flare are quite well known and have been used as a calibration for our study. We find that a giant flare impinging on Earth is not a threat for life in all practical situations, mainly because it is not as energetic, in spite of being much more frequent than GRBs, unless the source happens to be extremely close.