-
Habitability: a process versus a state variable framework with observational tests and theoretical implications Int. J. Astrobiol. (IF 2.026) Pub Date : 2021-01-21 A. Lenardic; J. Seales
The term habitable is used to describe planets that can harbour life. Debate exists as to specific conditions that allow for habitability but the use of the term as a planetary variable has become ubiquitous. This paper poses a meta-level question: What type of variable is habitability? Is it akin to temperature, in that it is something that characterizes a planet, or is something that flows through
-
Biological safety in the context of backward planetary protection and Mars Sample Return: conclusions from the Sterilization Working Group Int. J. Astrobiol. (IF 2.026) Pub Date : 2021-01-13 Emily Craven; Martell Winters; Alvin L. Smith; Erin Lalime; Rocco Mancinelli; Brian Shirey; Wayne Schubert; Andrew Schuerger; Mariko Burgin; Emily P. Seto; Morgan Hendry; Amruta Mehta; J. Nick Benardini; Gary Ruvkun
The National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are studying how samples might be brought back to Earth from Mars safely. Backward planetary protection is key in this complex endeavour, as it is required to prevent potential adverse effects from returning materials to Earth's biosphere. As the question of whether or not life exists on Mars today or whether
-
Solar system exposure to supernova γ radiation Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-11-04 G. Robert Brakenridge
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
-
Quantum chemical study on the formation of isopropyl cyanide and its linear isomer in the interstellar medium Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-11-24 Keshav Kumar Singh; Poonam Tandon; Alka Misra; Shivani; Manisha Yadav; Aftab Ahmad
The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN
-
Detection of pre-industrial societies on exoplanets Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-12-11 Andrew Lockley; Daniele Visioni
Approximately 22% of sun-like stars have Earth-like exoplanets. Advanced civilizations may exist on these, and significant effort has been expended on the theoretical analysis of planetary systems, and accompanying practical detection instruments. The longevity of technological civilizations is unknown, as is the probability of less advanced societies becoming technological. Accordingly, searching
-
Histidine adsorption onto modified montmorillonite under prebiotic chemistry conditions: a thermodynamic and kinetic study Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-12-01 Rafael Block Samulewski; Regiane Tamires Damasceno Guimarães; Dimas Augusto Morozin Zaia
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
-
Subsurface robotic exploration for geomorphology, astrobiology and mining during MINAR6 campaign, Boulby Mine, UK: part II (Results and Discussion) Int. J. Astrobiol. (IF 2.026) Pub Date : 2021-01-07 Thasshwin Mathanlal; Anshuman Bhardwaj; Abhilash Vakkada Ramachandran; María-Paz Zorzano; Javier Martín-Torres; Charles S. Cockell
Geomorphological studies of the hidden and protected subsurface environments are crucial to obtain a greater insight into the evolution of planetary landforms, hydrology, climate, geology and mineralogy. From an astrobiological point of view subsurface environments are of interest for their potential habitability as they are local environments that are partially or fully shielded from the high levels
-
Cosmology, astrobiology and the RNA world: just add quintessential water Int. J. Astrobiol. (IF 2.026) Pub Date : 2021-01-07 Keith Johnson
Laboratory generation of water nanoclusters from amorphous ice and strong terahertz (THz) radiation from water nanoclusters ejected from water vapour into a vacuum suggest the possibility of water nanoclusters ejected into interstellar space from abundant amorphous ice-coated cosmic dust produced by supernovae explosions. Water nanoclusters (section ‘Water nanoclusters’) offer a hypothetical scenario
-
Dyson swarms of von Neumann probes: prospects and predictions Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-30 Emir Haliki
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
-
Expecting the unexpected in the search for extraterrestrial life Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-06 Peter Vickers
On p. 10 of the 2018 National Academies Exoplanet Science Strategy document (NASEM 2018), ‘Expect the unexpected’ is described as a general principle of the exoplanet field. But for the next 150 pages, this principle is apparently forgotten, as strategy decisions are repeatedly put forward based on our expectations. This paper explores what exactly it might mean to ‘expect the unexpected’, and how
-
Distinguishing multicellular life on exoplanets by testing Earth as an exoplanet Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-01 Christopher E. Doughty; Andrew J. Abraham; James Windsor; Michael Mommert; Michael Gowanlock; Tyler Robinson; David E. Trilling
Can multicellular life be distinguished from single cellular life on an exoplanet? We hypothesize that abundant upright photosynthetic multicellular life (trees) will cast shadows at high sun angles that will distinguish them from single cellular life and test this using Earth as an exoplanet. We first test the concept using unmanned aerial vehicles at a replica moon-landing site near Flagstaff, Arizona
-
Habitable worlds of merging stars Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-06 Ivan I. Shevchenko
It is shown that W UMa-type and SX Phe-type stellar populations are both perfectly and uniquely suited for maintaining hyper-effective biopolymer chain reactions (BCR) on their planets once the planet is in the stellar habitable zone. W UMa-type stars are known to be contact binaries, and SX Phe-type stars are presumably post-binaries, i.e., products of stellar mergers. In case of the contact binaries
-
Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-12 Jianxun Shen
In Mars-analogous hyperarid soils of the Atacama Desert, phospholipid fatty acids (PLFAs) as the main component of biomembrane play a role in reliably determining viable microbes. PLFA analyses illustrated a rise of the microbial abundance (from 5.0 × 106 to 4.2 × 107 cells g−1) and biodiversity (from 7 to 15 different individual PLFAs) from the north hyperarid core of the Atacama Desert to the southern
-
Planck frequencies as Schelling points in SETI Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-11-19 Jason T. Wright
In SETI, when searching for ‘beacons’ – transmissions intended for us and meant to get our attention – one must guess the appropriate frequency to search by considering what frequencies would be universally obvious to other species. This is a well-known concept in game theory, where such solutions to a non-communicative cooperative game (such as a mutual search) are called ‘Schelling points’. It is
-
Survival and growth of soil microbial communities under influence of sodium perchlorates Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-29 Vladimir Cheptsov; Andrey Belov; Olga Soloveva; Elena Vorobyova; George Osipov; Natalia Manucharova; Michael Gorlenko
Previously conducted space missions revealed the presence of perchlorates, which are known to have a high oxidizing potential in Martian regolith, at the level of 0.5%. Due to hygroscopic properties and crystallization features of perchlorate-containing solutions, assumptions leading to the possibility of the existence of liquid water in the form of brines, which can contribute to the vital activity
-
Exploiting a perchlorate-tolerant desert cyanobacterium to support bacterial growth for in situ resource utilization on Mars Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-10-23 Daniela Billi; Beatriz Gallego Fernandez; Claudia Fagliarone; Salvatore Chiavarini; Lynn Justine Rothschild
The presence of perchlorate in the Martian soil may limit in-situ resource utilization (ISRU) technologies to support human outposts. In order to exploit the desiccation, radiation-tolerant cyanobacterium Chroococcidopsis in Biological Life Support Systems based on ISRU, we investigated the perchlorate tolerance of Chroococcidopsis sp. CCMEE 029 and its derivative CCMEE 029 P-MRS. This strain was obtained
-
Study of the formation of ferrihydrite under prebiotic chemistry conditions: artificial seawater 4.0 Gy and ammonium thiocyanate Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-09-15 Dimas A. M. Zaia; Murilo A. Coutinho; Dante H Mosca; Antônio C. S. da Costa; Alexandre Urbano
Among the several steps involved in molecular evolution, molecular preconcentration is the first and most important. If the molecules are not preconcentrated the other steps of molecular evolution cannot occur. There are several ways to preconcentrate molecules: sorption, wetting/drying cycles, freezing/sublimation and sorption/precipitation with minerals. In the present work, the effect of NH4SCN
-
Detection of organic or inorganic material in Martian meteorite Zagami by vibrational spectroscopy? Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-09-14 Bruno Leonardo do Nascimento-Dias; Maria Elizabeth Zucolotto; Hugo Camarano Belgo; Talita Valverde Ferreira da Silva; Virgĩlio de Carvalho dos Anjos
Zagami is a basaltic shergottite well characterized among Martian meteorites. For this reason, it is used as a reference sample to verify the feasibility of the vibrational spectroscopy techniques. In general, these techniques seeking extract spectral signatures from individual mineral present in the meteorite samples. Among some FTIR results were detected organic compounds in the Zagami meteorite
-
Planck frequencies as Schelling points in SETI Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-09-07 Jason T. Wright
In SETI, when searching for ‘beacons’ – transmissions intended for us and meant to get our attention – one must guess the appropriate frequency to search by considering what frequencies would be universally obvious to other species. This is a well-known concept in game theory, where such solutions to a non-communicative cooperative game (such as a mutual search) are called ‘Schelling points’. It is
-
SETI: the argument for artefact searches Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-09-02 Seth Shostak
For six decades, SETI has attempted to prove the existence of technologically advanced intelligence by detecting artificially generated electromagnetic signals. While such signals could certainly exist and – given the right circumstances – might be measurable here on Earth, contemporary searches are all compromised by limited sensitivity and a reliance on persistent transmissions. The energy required
-
The interstellar communication relay Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-08-26 Brian McConnell
The paper describes the architecture for a data repository and distribution system to be used in the case of a SETI detection event. This system is conceptually modelled after the Deep Space Network, although the hardware and infrastructure involved are different and substantially less expensive to operate. The system is designed to accommodate a large number of users from a variety of fields who wish
-
Artificial versus biological intelligence in the Cosmos: clues from a stochastic analysis of the Drake equation Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-06-23 Alex De Visscher
The Drake equation has been used many times to estimate the number of observable civilizations in the galaxy. However, the uncertainty of the outcome is so great that any individual result is of limited use, as predictions can range from a handful of observable civilizations in the observable universe to tens of millions per Milky Way-sized galaxy. A statistical investigation shows that the Drake equation
-
Attitudes and perceptions towards the scientific search for extraterrestrial life among students of public and private universities in Peru Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-06-30 Octavio A. Chon-Torres; Julio César Ramos Ramírez; Fernando Hoyos Rengifo; Rosana Aurora Choy Vessoni; Ivan Sergo Laura; Félix Germán Alfonso Ríos-Ruiz; César Andreé Murga-Moreno; José Percy Leonel Alvarado Pino; Ximena Yance-Morales
The objective of this study was to identify attitudes towards the scientific search for extraterrestrial life among students from public and private universities in Peru. This research was inspired by similar studies, realized in Sweden, which used the same instrument adapting it to our reality. The process consisted of a survey of the Peruvian student population by targeting it in different regions
-
An experimental study of the thermolysis of hydrogen cyanide: the role of hydrothermal systems in chemical evolution Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-07-06 Saúl A. Villafañe-Barajas; María Colín-García; Alicia Negrón-Mendoza; Marta Ruiz-Bermejo
Hydrogen cyanide (HCN) is considered a fundamental molecule in prebiotic chemistry experiments due to the fact that it could have an important role as raw material to form more complex molecules, as well as it could be an intermediate molecule in chemical reactions. However, the primitive scenarios in which this molecule might be available have been widely discussed. Hydrothermal systems have been
-
What's in a name: the etymology of astrobiology Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-07-01 Manasvi Lingam; Abraham Loeb
Astrobiology has been gaining increasing scientific prominence and public attention as the search for life beyond Earth continues to make significant headway on multiple fronts. In view of these recent developments, the fascinating and dynamic etymology of astrobiology is elucidated, and thus shown to encompass a plethora of vivid characters drawn from different continents, religions, ideologies and
-
Anomalous fluctuations and selective extinction in primordial replicators: a ‘struggle for life’ at the origin of biological homochirality Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-07-28 Savino Longo; Miriana Carmela Chincoli; Gaia Micca Longo
The prevalent presence of a single chiral variant of molecules in live organisms is one of the most distinctive signs of life as a global phenomenon. One of the greatest ambitions of biochemistry and astrobiology is to provide an explanation of this predominance. Several mechanisms were proposed in the past, from the propagation of chirality from a homo-chiral substrate to the amplification of effects
-
Monte Carlo estimation of the probability of causal contacts between communicating civilizations Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-08-11 M. Lares; J. G. Funes; L. Gramajo
In this work we address the problem of estimating the probabilities of causal contacts between civilizations in the Galaxy. We make no assumptions regarding the origin and evolution of intelligent life. We simply assume a network of causally connected nodes. These nodes refer somehow to intelligent agents with the capacity of receiving and emitting electromagnetic signals. Here we present a three-parametric
-
Contact inequality: first contact will likely be with an older civilization Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-08-24 David Kipping; Adam Frank; Caleb Scharf
First contact with another civilization, or simply another intelligence of some kind, will likely be quite different depending on whether that intelligence is more or less advanced than ourselves. If we assume that the lifetime distribution of intelligences follows an approximately exponential distribution, one might naively assume that the pile-up of short-lived entities dominates any detection or
-
Agent-based modelling of interstellar contacts using rumour spread models Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-08-11 Tevfik Uyar; Mehmet Emin Özel
Some stochastic model of rumours asserts that even an advanced communication network does not guarantee every agent hears certain news because they predict that rumour spreaders convert to stifflers when contacted with an informed agent. In this study, we adapted two rumour spread models to interstellar communication by developing an agent-based model (ABM) for exploring the issue more rigorously.
-
A limbus mundi elucidation of habitability: the Goldilocks Edge Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-05-22 Ian von Hegner
The habitable zone is the circumstellar region in which a terrestrial-mass planet with an atmosphere can sustain liquid water on its surface. However, despite the usefulness of this concept, it is being found to be increasingly limited in a number of ways. The following is known: (i) Liquid water can exist on worlds for reasons unrelated to its specific distance from a star. (ii) Energy sources can
-
Astrobiology and its influence on the renewal of the way we see the world from the teloempathic, educational and astrotheological perspective Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-05-28 Octavio A. Chon Torres
There is a record of the positive effects of astrobiological research for the natural sciences and eventually for their technological use on Earth. However, on the philosophical effects, this is not as visible as the other sciences, which is why it can be assumed that it is a waste of time speculating on astrobioethics or also on the philosophy of astrobiology. This is the reason why this work seeks
-
Interplanetary transmissions of life in an evolutionary context Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-05-27 Ian von Hegner
The theory of lithopanspermia proposes the natural exchange of organisms between solar system bodies through meteorites. The focus of this theory comprises three distinct stages: planetary ejection, interplanetary transit and planetary entry. However, it is debatable whether organisms transported within the ejecta can survive all three stages. If the conjecture is granted, that life can indeed be safely
-
Climate change via CO2 drawdown from astrophysically initiated atmospheric ionization? Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-05-28 Adrian L. Melott; Brian C. Thomas; Brian D. Fields
Motivated by the occurrence of a moderately nearby supernova near the beginning of the Pleistocene, possibly as part of a long-term series beginning in the Miocene, we investigated whether nitrate rainout resulting from the atmospheric ionization of enhanced cosmic ray flux could have, through its fertilizer effect, initiated carbon dioxide drawdown. Such a drawdown could possibly reduce the greenhouse
-
Does microgravity effect on oral and maxillofacial region? Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-05-26 Mark Stevens; Seied Omid Keyhan; Shohreh Ghasemi; Hamid Reza Fallahi; Shahriar Akbarnia; Mahmood Dashti; Fargol Mashhadi Akbar Boojar; Maneli Ardeshir Zadeh; Behzad Cheshmi
Since the beginning of the era of space travel, there have been mentions of related health effects. Various studies have described the effect of space travel and microgravity on health. Some of these studies involved short and extended follow-ups of the effect of microgravity on the head and neck of astronauts. Therefore, we aimed to analyse the oral and maxillofacial health effects associated with
-
Evolution of the number of communicative civilizations in the Galaxy: implications on Fermi paradox Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-04-23 Giorgio Spada; Daniele Melini
It has been recently proposed DeVito [(2019) On the meaning of Fermi's paradox. Futures, 389–414] that a minimal number of contacts with alien radio-communicative civilizations could be justified by their logarithmically slow rate of growth in the Galaxy. Here we further develop this approach to the Fermi paradox, with the purpose of expanding the ensemble of the possible styles of growth that are
-
Astrometric study of Gaia DR2 stars for interstellar communication Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-04-17 Naoki Seto; Kazumi Kashiyama
We discuss the prospects of high precision pointing of our transmitter to habitable planets around Galactic main sequence stars. For an efficient signal delivery, the future sky positions of the host stars should be appropriately extrapolated with accuracy better than the beam opening angle Θ of the transmitter. Using the latest data release (DR2) of Gaia, we estimate the accuracy of the extrapolations
-
Where are Solar storm-induced whale strandings more likely to occur? Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-04-13 Klaus Heinrich Vanselow
Whale strandings occur in many places worldwide and numerous possible explanations for this phenomenon have been proposed, including the effects of astronomical events such as Solar eruptions on the Earth's magnetic field. Whales use the geomagnetic field for navigation, and its distortion can therefore result in whale strandings in certain regions. However, Solar storms do not have the same impact
-
Intermittent signals and planetary days in SETI Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-04-01 Robert H. Gray
Interstellar signals might be intermittent for many reasons, such as targeted sequential transmissions, isotropic broadcasts that are not 'on' continuously or many other reasons. The time interval between such signals would be important, because searchers would need to observe for long enough to achieve an initial detection and possibly determine a period. This article suggests that: (1) the power
-
Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-03-09 Stefan Fox; Annika Gspandl; Franziska M. Wenng
In nature, abiotically formed amino acids are usually racemic. However, this is not true for the α,α-dialkyl amino acid isovaline (Iva), which has an L-enantiomeric excess in some specimens of carbonaceous meteorites. On the early Earth and Mars, such meteorites were sources of amino acids, including Iva. Therefore, a connection may exist between the possible chiral influence of non-racemic Iva and
-
Why should geological criteria used on Earth not be valid also for Mars? Evidence of possible microbialites and algae in extinct Martian lakes Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-03-02 Vincenzo Rizzo
During the Noachian period, 4.1-3.7 Gys ago, the Martian environment was moderately similar to the one on present Earth. Liquid water was widespread in a neutral environment, volcanic activity and heat flow more vigorous, and atmospheric pressure and temperature were higher than today. These conditions may have favoured the spread of life on the surface of Mars. The recognition that different planets
-
Earth-Like: an education & outreach tool for exploring the diversity of planets like our own Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-01-13 Elizabeth J. Tasker; Kana Ishimaru; Nicholas Guttenberg; Julien Foriel
Earth-Like is an interactive website and twitter bot that allows users to explore changes in the average global surface temperature of an Earth-like planet due to variations in the surface oceans and emerged land coverage, rate of volcanism (degassing) and the level of the received solar radiation. The temperature is calculated using a simple carbon–silicate cycle model to change the level of CO2 in
-
Exporting terrestrial life out of the Solar System with gravitational slingshots of Earthgrazing bodies Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-01-10 Amir Siraj; Abraham Loeb
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
-
Stability of α-ketoglutaric acid simulating an impact-generated hydrothermal system: implications for prebiotic chemistry studies Int. J. Astrobiol. (IF 2.026) Pub Date : 2020-01-07 L. Ramírez-Vázquez; A. Negrón-Mendoza
Life originated on Earth possibly as a physicochemical process; thus, geological environments and their hypothetical characteristics on early Earth are essential for chemical evolution studies. Also, it is necessary to consider the energy sources that were available in the past and the components that could have contributed to promote chemical reactions. It has been proposed that the components could
-
Will recent advances in AI result in a paradigm shift in Astrobiology and SETI? Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-12-03 Joe Gale; Amri Wandel; Hugh Hill
The steady advances in computer performance and in programming raise the concern that the ability of computers would overtake that of the human brain, an occurrence termed ‘the Singularity’. While comparing the size of the human brain and the advance in computer capacity, the Singularity has been estimated to occur within a few decades although the capacity of conventional computers may reach its limits
-
Probing the response of Deinococcus radiodurans exposed to simulated space conditions Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-11-19 Gabriel Guarany de Araujo; Fabio Rodrigues; Douglas Galante
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,
-
Nine axes of merit for technosignature searches Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-11-19 Sofia Z. Sheikh
It can be difficult to develop an effective and balanced search strategy in SETI, especially from a funding perspective, given the diverse methodologies and myriad orthogonal proposals for the best technosignatures. Here I propose a framework to compare the relative advantages and disadvantages of various proposed technosignatures based on nine ‘axes of merit’. This framework was first developed at
-
Effect of γ-radiation on adenine dissolved in distilled water, saline solutions and artificial seawater resembling that of 4.0 billion years ago Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-11-15 João Paulo T. Baú; Sául A. Villafañe-Barajas; Alicia Negrón-Mendoza; María Colín-García; Dimas A. M. Zaia
In this work, the effect of γ-radiation on the decomposition of adenine dissolved in distilled water, saline solutions and artificial seawater was studied. As the composition of the major cations and anions of artificial seawater probably better resembles the composition of seawater on the Earth 4.0 billion years ago, this seawater was named artificial seawater 4.0 Ga. The main finding in this work
-
The search for microbial Martian life and American Buddhist ethics Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-11-14 Daniel Capper
Multiple searches hunt for extraterrestrial life, yet the ethics of such searches in terms of fossil and possible extant life on Mars have not been sufficiently delineated. In response, in this essay, I propose a tripartite ethic for searches for microbial Martian life that consists of default non-harm towards potential living beings, default non-harm to the habitats of potential living beings, but
-
The fate of proteins in outer space. Int. J. Astrobiol. (IF 2.026) Pub Date : 2017-01-01 Gavin M Seddon,Robert P Bywater
It is well established that any properly conducted biophysical studies of proteins must take appropriate account of solvent. For water-soluble proteins it has been an article of faith that water is largely responsible for stabilizing the fold, a notion that has recently come under increasing scrutiny. Further, there are some instances when proteins are studied experimentally in the absence of solvent
-
Life is determined by its environment. Int. J. Astrobiol. (IF 2.026) Pub Date : 2016-10-07 John S Torday,William B Miller
A well-developed theory of evolutionary biology requires understanding of the origins of life on Earth. However, the initial conditions (ontology) and causal (epistemology) bases on which physiology proceeded have more recently been called into question, given the teleologic nature of Darwinian evolutionary thinking. When evolutionary development is focused on cellular communication, a distinctly different
-
Photosynthesis on exoplanets and exomoons from reflected light Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-10-31 Manasvi Lingam; Abraham Loeb
Photosynthesis offers a convenient means of sustaining biospheres. We quantify the constraints for photosynthesis to be functional on the permanent nightside of tidally locked rocky exoplanets via reflected light from their exomoons. We show that the exomoons must be at least half the size of Earth's moon in order for conventional oxygenic photosynthesis to operate. This scenario of photosynthesis
-
On the interstellar Von Neumann micro self-reproducing probes Int. J. Astrobiol. (IF 2.026) Pub Date : 2019-10-17 Z. Osmanov
In this paper we consider efficiency of self-reproducing extraterrestrial Von-Neumann micro scale robots and analyse the observational characteristics. By examining the natural scenario of moving in the HII clouds, it has been found that the timescale of replication might be several years and even less – making the process of observation quite promising. We have shown that by encountering the interstellar
-
Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures Int. J. Astrobiol. (IF 2.026) Pub Date : 2018-10-11 Shiladitya DasSarma; Edward W. Schwieterman
We propose that retinal-based phototrophy arose early in the evolution of life on Earth, profoundly impacting the development of photosynthesis and creating implications for the search for life beyond our planet. While the early evolutionary history of phototrophy is largely in the realm of the unknown, the onset of oxygenic photosynthesis in primitive cyanobacteria significantly altered the Earth's
-
A profile of humanity: the cultural signature of Earth's inhabitants beyond the atmosphere Int. J. Astrobiol. (IF 2.026) Pub Date : 2018-08-15 Paul E. Quast
The eclectic range of artefacts and ‘messages’ we dispatch into the vast expanse of space may become one of the most enduring remnants of our present civilization, but how does his protracted legacy adequately document the plurality of societal values and common, cultural heritage on our heterogeneous world? For decades now, this rendition of the egalitarian principle has been explored by the Search
-
Disciplinary nature of astrobiology and astrobioethic’s epistemic foundations Int. J. Astrobiol. (IF 2.026) Pub Date : 2018-08-10 Octavio A. Chon-Torres
Astrobioethics is an emerging discipline that studies, evaluates and analyses the moral, legal and social issues of the search for life in the Universe. As a new field of study, it requires an epistemological foundation to be able to be recognized as an academic discipline. In order to achieve this, it is important to understand the disciplinary nature of astrobiology as a transdisciplinary form of
-
Effects of temperatures and high pressures on the growth and survivability of methanogens and stable carbon isotope fractionation: implications for deep subsurface life on Mars Int. J. Astrobiol. (IF 2.026) Pub Date : 2018-08-02 Navita Sinha; Sudip Nepal; Timothy Kral; Pradeep Kumar
In order to examine the potential survivability of life in the Martian deep subsurface, we have investigated the effects of temperature (45°C, 55°C and 65°C) and pressure (1, 400, 800 and 1200 atm) on the growth, carbon isotopic data and morphology of chemolithoautotrophic anaerobic methanogenic archaea, Methanothermobacter wolfeii. The growth and survivability of this methanogen were determined by
-
Low-Latency Teleoperations, Planetary Protection, and Astrobiology. Int. J. Astrobiol. (IF 2.026) Pub Date : 2017-11-08 Mark Lupisella,Margaret S Race
Low-latency teleoperations (LLT), or "telepresence" allows for the control of almost any asset in essentially real-time and has significant potential to address potential planetary protection concerns and to enhance astrobiology exploration activities on both robotic and human missions to Mars and elsewhere in the solar system. LLT can assist with the search for extraterrestrial life and help mitigate
Contents have been reproduced by permission of the publishers.