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The interest in the possibility of life on Venus is driven not just by curiosity about life originating in another Earth-like environment, but because of the possibility that life may be playing a critical role in the planet’s present, and possibly its past, atmospheric state. The brilliance of Venus in the night sky (as viewed from Earth) is due to its highly reflective cloud cover, about 28 km thick at the equator. Its spectral albedo is about 90% at wavelengths > 500 nm, but it drops gradually to about 40% around 370 nm before rising slightly at shorter wavelengths. This albedo drop is due to the presence of several absorbers in the atmosphere and the cloud cover. A very large fraction of the energy absorbed by Venus is at ultraviolet wavelengths with sulfur dioxide above the clouds contributing to the absorption below 330 nm; however, the identities of the other absorbers remain unknown. The inability to identify the absorbers that are responsible for determining the radiative energy balance of Venus over the last century is a major impediment to understanding how the planet “works”, a major component of NASA’s efforts in planetary exploration. Limaye et al. (Astrobiology 18, 1181-1198, 2018) presented a hypothesis suggesting that cloud-based microbial life could be contributors to the spectral signatures of Venus’ clouds, building upon previous suggestions of the possibility of life in the clouds of Venus.Four interconnected themes for the exploration of Venus as an astrobiology target are: – (i) investigations focused on the likelihood that liquid water existed on the surface in the past leading to the potential for the origin and evolution of life, (ii) investigations into the potential for habitable zones within Venus’ clouds and Venus-like atmospheres, (iii) theoretical investigations into how active aerobiology may impact the radiative energy balance of Venus’ clouds and Venus-like atmospheres, and (iv) application of these investigative themes towards better understanding the atmospheric dynamics and habitability of exoplanets. These themes can serve as a basis for proposed Venus Astrobiology Objectives and suggestions for measurements for future missions, as per the goals and objectives developed by the Venus Exploration Analysis Group (VEXAG), which is sponsored by NASA to plan for the future exploration of Venus. A Venus Collection to be published in Astrobiology journal in 2021 will include papers from the “Habitability of the Venus Cloud Layer”, Moscow (October 2019) workshop.

We present a case for the exploration of Venus as an astrobiology target—(1) investigations focused on the likelihood that liquid water existed on the surface in the past, leading to the potential for the origin and evolution of life, (2) investigations into the potential for habitable zones within Venus’ present-day clouds and Venus-like exo atmospheres, (3) theoretical investigations into how active aerobiology may impact the radiative energy balance of Venus’ clouds and Venus-like atmospheres, and (4) application of these investigative approaches toward better understanding the atmospheric dynamics and habitability of exoplanets. The proximity of Venus to Earth, guidance for exoplanet habitability investigations, and access to the potential cloud habitable layer and surface for prolonged in situ extended measurements together make the planet a very attractive target for near term astrobiological exploration.

It is proposed that the primary living cells (&ldquo, probionts&rdquo, ) cannot emerge of organic substance simply by continuous chemical complication of prebiotic macromolecules and microsystems. The complication must be accompanied by the radical thermodynamic transformation (&ldquo, jump&rdquo, ) of prebiotic microsystems that resulted in the acquired ability to extract free energy from the environment and export entropy. This transformation is called &ldquo, the thermodynamic inversion&rdquo, The inversion may occur by means of the efficient (intensified) response of the microsystems on the oscillations of physic-chemical parameters in hydrothermal environment. In this case the surplus available free energy within a microsystem, when combined with the informational modality, facilitates its conversion into a new microsystem&mdash, a living probiont. It is shown the schematic representation of an oscillating prebiotic microsystem that is transforming into a living probiont. A new kind of laboratory and computational experiments on prebiotic chemistry under oscillating conditions is offered to verify the inversion concept.

The aim of this study consists in the advancement of the author’s dichotomous hypothesis of hot origin of the solar system that is alternate to the well-known hypotheses of cold accretion. The hypothesis proposes formation of solar planets and satellites through dichotomous division of the superheated protoplanetary mass ejected from the youngest Sun due to strong non-equilibrium competition between gravitational contraction and heat expansion. Like the cold accretion hypotheses, the dichotomous hypothesis also explains the key regularities of the solar system structure (angular momentum distribution, position of the asteroid belt, back rotation of Venus and Uranus, etc.). Besides, it offers explanation of new data on extra solar planetary systems that is difficult to understand basing on the gradual cold accretion process (in particular, the misaligned protoplanetary discs in the binary protostar IRS 43). Some predictions following of the given explanation can be examined during future observations. The proposed hot origin of planets and satellites provides some new opportunities and directions for search of life in the solar system, including comets and hydrothermal environments on Mars and Europa.

This paper reports the analyses of unusual oils that accumulate in the Uzon Caldera, situated in the central volcanic region of Kamchatka, Russia. Gas chromatography–mass spectrometry (GC–MS) was used to determine the primary constituents, and the 13 C and 14 C compositions provided information about the potential source and age of the oils. The 14 C ages determined are 1030 ± 40 a BP (measured) or 940 ± 40 a BP (conventional). The δ 13 C value is −30.6‰ versus the PDB standard, a value consistent with a biological origin. The nearly contemporary age of the C content indicates a geologically recent origin from biogenic detritus and not by synthesis from mantle C. The biogenic origin is supported by the presence of sterane and hopane biomarkers and the δ 13 C value of the bulk oil. The overall compositions of the oils indicate that they are derived from rapid hydrothermal alteration of algal/bacterial mat detritus buried by volcanic ashfall deposits of the Uzon Caldera. The oils represent the youngest hydrothermal petroleum reported to date.

Biological organization arises under thermodynamic inversion in prebiotic systems that provide the prevalence of free energy and information contribution over the entropy contribution. The inversion might occur under specific far-from-equilibrium conditions in prebiotic systems oscillating around the bifurcation point. At the inversion moment, (physical) information characteristic of non-biological systems acquires the new features: functionality, purposefulness, and control over the life processes, which transform it into biological information. Random sequences of amino acids and nucleotides, spontaneously synthesized in the prebiotic microsystem, in the primary living unit (probiont) re-assemble into functional sequences, involved into bioinformation circulation through nucleoprotein interaction, resulted in the genetic code emergence. According to the proposed concept, oscillating three-dimensional prebiotic microsystems transformed into probionts in the changeable hydrothermal medium of the early Earth. The inversion concept states that spontaneous (accidental, random) transformations in prebiotic systems cannot produce life; it is only non-spontaneous (perspective, purposeful) transformations, which are the result of thermodynamic inversion, that lead to the negentropy conversion of prebiotic systems into initial living units.

The decisive step in the transformation of prebiotic microsystems into the simplest living units (probionts) consisted of the inversion of a thermodynamic trend toward greater entropy. Following this event, the contribution of free energy and information in the microsystem began to prevail over the contribution of entropy. The initial three-dimensional prebiotic microsystems composed mainly of hydrocarbons, lipids, and simple amino acids spontaneously self-assembled in hydrothermal media on the early Earth. The biological method of organization started at the inversion together with the nonspontaneous synthesis of more complex biomolecules under fluctuating nonequilibrium conditions. The accumulating information was concentrated in the core of a probiont. Circulation of bioinformation between the conserved (replicative) and active (functional) forms gave rise to the initial interaction between nucleic acids and protein catalysts. The inversion approach described here is universal and would occur on all planets occupying habitable zones around stars as long as they had liquid water, organic carbon compounds, and a source of free energy to drive chemical reactions toward increasingly complex polymers.

In present cells nucleotides and amino acids are linked together in heteropolymeric sequences, rich in bioinformation. The genetic code analysis suggests that an incessant search for enhanced perfo...

The essence of the inversion concept of the origin of life can be narrowed down to the following theses: (1) thermodynamic inversion is the key transformation of prebiotic microsystems leading to their transition into primary forms of life; (2) this transformation might occur only in the microsystems oscillating around the bifurcation point under far-from-equilibrium conditions. The transformation consists in the inversion of the balance “free energy contribution entropy contribution” (as well as “information contribution informational entropy contribution”), from negative to positive values. At the inversion moment, the microsystem radically reorganizes in accordance with the new negentropy (i.e. biological) way of organization. According to this concept, the origin-of-life process on the early Earth took place in oscillating hydrothermal medium. The process was taking two successive stages: (1) spontaneous self-assembly of initial three-dimensional prebiotic microsystems composed mainly of hydrocarbons,...