Julian Chela-Flores

Exobiology: Matter, Energy, and Information in the Origin and Evolution of Life in the Universe

Preface. Opening Address F.K.A. Allotey. Section 1: General Overview. Section 2: Matter in the Origin and Evolution of Life in the Universe. Section 3: Energy from Inert to Living Matter. Section 4: Information. Section 5: Early Evolution. Section 6: Exobiology: General Perspectives. Section 7: Exobiology on Mars and Europa. Section 8: The Interstellar Medium, Comets and Chemical Evolution. Section 9: Exobiology on Titan. Section 10: Extrasolar Planets. Section 11: Search for Extraterrestrial Intelligence. Author Index. Subject Index. List of Participants.

Instrumentation for the search for habitable ecosystems in the future exploration of Europa and Ganymede

The extensive evidence of an ocean over a silicate nucleus makes Europa a candidate for the emergence of a second evolutionary pathway of autochthonous life. We argue that the most urgent question in astrobiology is the origin of habitable ecosystems (a question in geochemistry), rather than the alternative search for the origin of life itself (a question in chemical evolution). Since certain Solar System bodies may share a similar geophysical past with Earth, our more modest approach forces upon us the question: Can available instrumentation be the ‘pioneer’ in the discovery of habitable ecosystems in geophysical environments similar to the early Earth? It will be shown that a central piece in this dilemma is the chemical element sulphur (S). The Europan non-ice surficial elements that distort the water–ice absorption bands were found to be widespread, patchy and, most likely, endogenous. The Galileo Mission discovered these patches, which were subsequently confirmed by the 2007 flyby of New Horizons. We argue that penetrators should be inserted into orbital probes in the future exploration of Jupiters System. Penetrators provide what could be a key instrument in the exploration of Europa, given the adverse space weather in its environment due to the Jovian magnetosphere and radiation. Indeed, there are alternative views on the radiation-induced S-cycles produced on the surficial molecules that are present on the icy surface; however, S is common to both interpretations. Hence, mass spectrometry should be an essential part of any future payload. The largest S-fractionations are due to microbial reduction and not to thermochemical processes, allowing a test of the hypothesis for the origin of habitable ecosystems. The microbial fractionation of stable S-isotopes argue in favour of penetrators for the survey of the surfaces of both Europa and Ganymede.

The sulphur dilemma: are there biosignatures on Europa's icy and patchy surface?

We discuss whether sulphur traces on Jupiter’s moon Europa could be of biogenic origin. The compounds detected by the Galileo mission have been conjectured to be endogenic, most likely of cryovolcanic origin, due to their non-uniform distribution in patches. The Galileo space probe first detected the sulphur compounds, as well as revealing that this moon almost certainly has a volcanically heated and potentially habitable ocean hiding beneath a surface layer of ice. In planning future exploration of Europa there are options for sorting out the source of the surficial sulphur. For instance, one possibility is searching for the sulphur source in the context of the study of the Europa Microprobe In Situ Explorer (EMPIE), which has been framed within the Jovian Minisat Explorer Technology Reference Study (ESA). It is conceivable that sulphur may have come from the nearby moon Io, where sulphur and other volcanic elements are abundant. Secondly, volcanic eruptions in Europa’s seafloor may have brought sulphur to the surface. Can waste products rising from bacterial colonies beneath the icy surface be a third alternative significant factor in the sulphur patches on the Europan surface? Provided that microorganisms on Europa have the same biochemical pathways as those on Earth, over geologic time it is possible that autochthonous microbes can add substantially to the sulphur deposits on the surface of Europa. We discuss possible interpretations of the non-water-ice elements (especially the sulphur compound mercaptan) in the context of the studies for future missions. To achieve reliable biosignatures it seems essential to go back to Europa. Our work highlights the type of biogenic signatures that can be searched for when probing Europa’s icy and patchy surface. Received 9 November 2005, accepted 28 February 2006

Gauge theory of superfluidity

We study a gauge theory of superfluidity in4He II. An illustration of how the gauge principle leads to a meaningful low temperature theory is given. We then infer and study the field equations, writing them down in their hydrodynamical form. Applications to some simple hydrodynamical problems are considered.

Returning to Europa: can traces of surficial life be detected?

There is at present a possibility for returning to Europa with LAPLACE, a mission to Europa and the Jupiter System for European Space Agencys Cosmic Vision Programme. The question of habitability by the identification of reliable bio-indicators is a major priority. We explain the options for approaching the question of selecting the right instrumentation for measuring the more abundant sulphur isotope, in spite of the fact that 32 S is isobaric (same m/z) with 16 O2. Two technologies are available for investigating the possible biogenicity of the surficial sulphur on the icy patches discovered by the Galileo mission. We argue that there is a need to use higher-order statistics in the data that are to be gathered with the instruments chosen for the payload (ion-traps for orbital measurements, or penetrators for surficial measurements). In particular, we argue in favour of data analysis taken from an orbital spacecraft that addresses fluctuations of the data retrieved, rather than the mean. For this purpose, we reconsider the significance of deviations of sulphur abundances relative to normal (meteoritic) values. In the present work, we consider the experimentally testable possibility of biogenically driven isotopic anomalies in the light of statistical data analysis. The fluctuation test that is being proposed in the context of future missions to Europa may well be appropriate to a laboratory experiment with sulphur-reducing bacteria with the corresponding isotopic fractionation.

Testing the universality of biology: a review

Abstract We discuss whether it is possible to test the universality of biology, a quest that is of paramount relevance for one of its most recent branches, namely astrobiology. We review this topic in terms of the relative roles played on the Earth biota by contingency and evolutionary convergence. Following the seminal contribution of Darwin, it is reasonable to assume that all forms of life known to us so far are not only terrestrial, but are descendants of a common ancestor that evolved on this planet at the end of a process of chemical evolution. We also raise the related question of whether the molecular events that were precursors to the origin of life on Earth are bound to occur elsewhere in the universe, wherever the environmental conditions are similar to the terrestrial ones. We refer to ‘cosmic convergence’ as the possible occurrence elsewhere in the universe of Earth-like environmental conditions. We argue that cosmic convergence is already suggested by observational data. The set of hypotheses for addressing the question of the universality of biology can be tested by future experiments that are feasible with current technology. We focus on landing on Europa and the broader implications of selecting the specific example of the right landing location. We had discussed earlier the corresponding miniaturized equipment that is already in existence. The significance of these crucial points needs to be put into a wider scientific perspective, which is one of the main objectives of this review. MIRAMARE – TRIESTE May 2007

Evolution as a collective phenomenon

The quantum mechanical description of biosystems, which emphasise their dielectric properties and the presence of an uncorrelated condensate of phonons, (in analogy with Bose-Einstein condensation), is extended to a description of biosystems, in which the condensed phonons show anomalous averages, (in analogy with superconductivity). The theory is used to show that a quantum ultraviolet defence mechanism may have been present at the origin of chemical evolution, removing a difficulty in the standard scenario. Suggestions are made as to how to proceed experimentally to show the existence of a correlated phonon condensate.

Testing evolutionary convergence on Europa

A major objective in solar system exploration is the insertion of appropriate biology-oriented experiments in future missions. We discuss various reasons for suggesting that this type of research be considered a high priority for feasibility studies and, subsequently, for technological development of appropriate melters and submersibles. Based on numerous examples, we argue in favour of the assumption that Darwins theory is valid for the evolution of life anywhere in the universe. We have suggested how to obtain preliminary insights into the question of the distribution of life in the universe. Universal evolution of intelligent behaviour is at the end of an evolutionary pathway, in which evolution of ion channels in the membrane of microorganisms occurs in its early stages. Further, we have argued that a preliminary test of this conjecture is feasible with experiments on the Europan surface or ocean, involving evolutionary biosignatures (ion channels). This aspect of the exploration for life in the solar system should be viewed as a complement to the astronomical approach for the search of evidence of the later stages of the evolutionary pathways towards intelligent behaviour.

From systems chemistry to systems astrobiology: life in the universe as an emergent phenomenon

Although astrobiology is a science midway between the life and physical sciences, it has surprisingly remained largely disconnected from recent trends in certain branches of both life and physical sciences. We discuss potential applications to astrobiology of approaches that aim at integrating rather than reducing. Aiming at discovering how systems properties emerge has proved valuable in chemistry and in biology. The systems approach should also yield insights into astrobiology, especially concerning the ongoing search for alternative abodes for life. This is feasible since new data banks in the case of astrobiology-considered as a branch of biology-are of a geophysical/astronomical kind, rather than the molecular biology data that are used for questions related ! rstly, to genetics in a systems context and secondly, to biochemistry for solving fundamental problems, such as protein or proteome folding. By focusing on how systems properties emerge in astrobiology we consider the question: can life in the universe beinterpretedasanemergentphenomenon?Inthesearchforpotentialhabitableworldsinourgalacticsector with current space missions, extensive data banks of geophysical parameters of exoplanets are rapidly emerging. We suggest that it is timely to consider life in the universe as an emergent phenomenon that can be approached with methods beyond the science of chemical evolution-the backbone of previous research in questions related to the origin of life. The application of systems biology to incorporate the emergence of life in the universe is illustrated with a diagram for the familiar case of our own planetary system, where three Earth-like planets arewithin the habitable zone (HZ) of a G2 V (the complete terminology for the Sun in the Morgan-Keenan system) star. We underline the advantage of plotting the age of Earth-like planets against large atmospheric fraction of a biogenic gas, whenever such anomalous atmospheres are discovered in these worlds. A prediction is made as to the nature of the atmospheres of the planets that lie in the stellar HZs. Introduction: space probes for searching the emergence of life in the universe We assume a close integration of the phenomenon of life and all cosmic matter, both dark and visible. We further assume that life is subject to evolutionary convergence. The close integration of life and matter forms a single and self- regulating complex system, maintaining the conditions for life in the universe. Our aim is to set the basis for a theoretical biology interpretation of the ongoing measurements of the local sector of our galaxy by current and future space probes. We argue that our hypothesis of viewing the cosmos as a single complex system can lead to insights into the phenom- enon of life interpreted as an emergent phenomenon with testable predictions that have escaped the standard approach of chemical evolution. We refer the readers to extensive reviews of the considerable achievements of the earlier successes of chemical evolution (Ponnamperuma &

Search for Bacterial Waste as a Possible Signature of Life on Europa

Of particular interest to the scientific community is the possible existence of extraterrestrial biological activity due to the presence of liquid water under the icy surface. This search is motivated by analogy with anaerobic life found in abundance in under sea volcanic vents on Earth (McCollom 1999; Pappalardo et al., 1999) and the dry valley lakes of Antarctica. If Europa does indeed have a liquid water ocean beneath the outer ice crust as a result of interior volcanic heating, then it is possible that hydrothermal vents located on the seafloor may provide the necessary conditions for simple ecosystems to exist. The water ejected from the hydrothermal vents is typically rich in sulfur and other minerals. Bacteria present in the water extract all nutrients directly from the sulfur via chemosynthesis, making sunlight and oxygen unnecessary. Geochemical models have been proposed to explore the possibility that lithoautotropic methanogenesis (CO2 + 4H2 = CH4 + 2H2O) could be a source of metabolically useful chemical energy for the production of biomass at putative Europan hydrothermal systems (McCollom, 1999; Delitsky and Lane, 1997). In the absence of oxygen, anaerobic decomposition takes place in these hydrothermal vents. As a result of putrefactive breakdown of organic material (proteins), some elements are produced, such as hydrogen sulfide, methane, ammonia, and mercaptans, which are thiols/thio alcohols (RS-H, R-paraffinic, aromatic or cyclopraffine group). The sulfur in mercaptans found in bacteria ultimately derives from sulfate (-SO2- 4), which is reduced in the cell. In bacteria that utilize sulfate as a source of sulfur, several steps in the reduction process eventually lead to hydrogen sulfide (H2S) which is a direct precursor of the amino acid cysteine which is a thiol! The original source of sulphur on the Europan surface may be either: (a) ions implanted from the Jovian plasma, or alternatively, (b) much of the sulphurous material may be endogenic.