Exobiological Experiments Research Articles

Interspecific differences in cryoresistance of lichen symbiotic algae of genus Trebouxia assessed by cell viability and chlorophyll fluorescence

Unicellular algae of genus Trebouxia are the most frequent symbiotic photobionts found in lichen species adapted to extreme environments. When lichenised, they cope well with freezing temperature of polar regions, high-mountains environments and were successfully tested in open-space experiments. Trebouxia sp. is considered potential model species for exobiological experiments. The aim of this paper is to evaluate cryoresistence of Trebouxia sp. when isolated from lichen thalli and cultivated on media. In our study, six algal strains were exposed to repeated freezing/thawing cycles. The strains of Trebouxia sp. (freshly isolated from lichen Lasallia pustulata), Trebouxia erici, Trebouxia asymmetrica, Trebouxia glomerata, Trebouxia irregularis, and Trebouxia jamesii from culture collection were cooled from 25 to −40°C at two different rates. The strains were also shock frozen in liquid nitrogen. After repeated treatment, the strains were inoculated and cultivated on a BBM agar for 7days. Then, cell viability was assessed as relative share of living cells. Potential quantum yield of photochemical reactions in PS II (FV/FM), and effective quantum yield of photochemical reactions in PS II (ΦPSII) were measured. While the slow cooling rate (0.5°Cmin−1) did not cause any change in viability, FV/FM, and ΦPSII, the fast cooling rate (6.0°Cmin−1) caused species-specific decrease in all parameters. The most pronounced interspecific differences in cryoresistance were found after shock freezing and consequent cultivation. While T. asymmetrica and T. jamesii exhibited low viability of living cells (18.9% and 34.7%) and full suppression of photosynthetic processes, the other strains had viability over 60%, and unaffected values of FV/FM, and ΦPSII. This indicated a high degree of cryoresistance of T. glomerata, T. erici, T. irregularis and Trebouxia sp. strains. These strains could be used for detailed investigation of underlying physiological mechanisms and as models for astrobiological tests taken in the Earth facilities.

Cosmic ray detection on the Foton-M2 satellite by a track etch detector stack

In the frame of the European Space Agency (ESA) project called “Biology and Physics in Space”, the returning satellite, Foton-M2, carried an open-to-space exposure platform outside of the satellite body, called as BIOPAN-5, loaded with exo-biological experiments and facilities for radiation dosimetry (RADO). One of the RADO experiments was dedicated to the detection of the primary galactic cosmic rays (GCR) and secondary neutrons by a track etch detector stack. The daily absorbed dose ( D) and dose equivalent ( H) were calculated from the experimental LET spectra (LET > 10 keV/μm). Under a shielding of ∼2.8 g/cm 2 the averaged H was found to be 658 ± 8 μSv/d, with a quality factor ( Q) of 6.2 ± 1.2. The LET spectra showed a local peak at ∼105 keV/μm suggesting that the majority of tracks were created by trapped protons as it has been predicted by calculations. The low LET dose of the cosmic radiation was determined by 4 TLD stacks, and the total dose was found to be 795 ± 14 μSv/d.

Depth dose distribution measurement on the Foton-M2 bio-satellite by TLD technique

In the framework of “Biology and Physics in Space” project of the European Space Agency (ESA), a returning satellite, Foton-M2, carried an open-to-space sample holder outside of the satellite body, called as BIOPAN-5, loaded with exo-biological experiments and dosemeters for RAdiation DOsimetry (RADO). One of the RADO experiments (Teflon – TLD) was dedicated to dose distribution measurements of the cosmic radiation by thermo-luminescent (TL) technique. It was found that the maximum surface absorbed dose rate, averaged over the first ∼8 mg/cm 2 thickness, was ∼2 Gy/d and showed a location dependence due the shading effect of the satellite construction elements. The dose rate decreased nearly by 3 orders of magnitude below 500 mg/cm 2.

Beagle-2 position determination from the returned camera panoramas using MOLA data

After the Beagle-2 lander of the Mars Express mission comes to rest on the surface of Isidis Planitia in late December 2003 to carry out a range of geochemistry and exobiology experiments, there will be considerable interest in determining its exact location. This work considers the feasibility of identifying topographic features seen in the Mars Global Surveyor MOLA dataset in images of the horizon returned by the lander, and the probability of observing lesser features identifiable in orbital imagery. By taking bearings from such features, and attempting to match the configuration back to the available data, it may be possible to determine the spacecraft's position with high precision. Since the MOLA data is fairly coarse compared to the area of the landing ellipse, the range of visibility and likelihood of observation of each of the resolved craters in the area is considered. For the more numerous smaller craters and many small knobs a probabilistic view is taken.

Growth of a lower eukaryote in non-aromatic hydrocarbon media ⩾C 12 and its exobiological significance

The fungus termed Fusarium alkanophyllum Palacios-Prü & V. Marcano is able to grow in and degrade several saturated hydrocarbons in the presence of UV radiation at 253.7 nm or 354.5 nm , H 2O 2, and CO 2, with little or no oxygen and with minimum water requirements showing several phenotypes and optimal growth. Further, this species is also able to produce important amounts of metabolic water from the substrate. Therefore, different simulation experiments were done to evaluate the biological, physiological and biochemistry responses taking into account conditions similar to solar and extrasolar environments having various CO 2 contents and occupying the habitable zone around the main sequence stars with spectral types in the F to mid-K range with L ( L/) ∼1. Solar and extrasolar environments similar to those of the jovian satellites and Titan were also considered. Accordingly, the growth of F. alkanophyllum was inhibited in < n-C 10 or aromatic hydrocarbons. The organism is proteolytic, since it grows in culture media of hydrocarbons containing albumin, glycoprotein and gammaglobulin as a source of carbon and nitrogen; however, in media containing other proteins that lack sulphur linkages, no growth was observed. Analysis by electron microscopy (EM) of F. alkanophyllum grown from germinated spores in heavy and light hydrocarbon media in the presence or absence of UV radiation and oxidizing or reducing gases revealed the absence of plasmalemma, nuclear membranes and other cytomembranes as an adaptative response. Aqueous extracts of secreted material from several hydrocarbon cultures analysed by FTIR spectroscopy revealed the presence of fatty acids and UV-protective indole pigments. An additional protection against UV radiation is offered by the hydrocarbon media which have substantial absorbances between 200 and 354 nm . The absence of lipidic membranes in F. alkanophyllum constitute an important finding in the cell biology of the terrestrial species that deserve careful evaluation. The results of this work allows to encourage exobiology experiments utilizing extremophile eukaryotes such as fungi in the International Space Station or on Mars. Moreover, the study of the physiological mechanisms involved in anhydrous conditions must be of interest in the exobiology of solar and extrasolar bodies having hydrocarbon potential niches because it offers an alternative vision related with the search for life in the universe.

Planetary protection requirements for orbiter and netlander elements of the CNES/NASA Mars sample return mission

In the framework of Mars exploration, particularly for missions dedicated to the search for life or for traces of ancient forms of life, NASA and CNES have decided to join their efforts in order to build a Mars sample return mission. Taking into account article IX of the OUTER SPACE TREATY (Treaty on principles governing the activities of states in the exploration and use of outer space, including the Moon and other celestial, referenced 610 UNTS 205 - resolution 2222(XXI) of December 1966, ratified in London / Washington January 27, 1967) and in order to comply with the COSPAR planetary protection recommendations, a common planetary protection program has to be established. Mars in-situ experimentations are limited by the size and the mass of the instruments necessary to perform exobiology investigations and, consequently, it appears that the best way to conduct such experiments is to bring back Mars samples to Earth. A sample return mission enables the use of a very large number of instruments and analysis protocols, giving exobiologists the best chance to find living entities or organic compounds related to life. Such a mission is complicated from a planetary protection point of view, it combines constraints for the protection of both the Mars environment as well as Earth, including the preservation of samples to ensure the validity of exobiological experiments.

A ground-based program for exobiological experiments on the International Space Station

The International Space Station will carry the external facility EXPOSE for exobiological studies under free space conditions and/or selected space parameters. Complementary to such experimentation in space, a profound ground support program under simulated space conditions is required: (i) to support the scientific EXPOSE community in the definition of the experiments under simulated space conditions; (ii) to determine the compatibility of the different experiments (e.g., organics and biology); (iii) to optimize the experiments; (iv) to perform experiments sequence tests under simulated EXPOSE environment conditions; (v) to run ground controls in parallel to the mission; and (vi) for postflight analysis of phenomena observed in space. For these laboratory studies, testbeds are available at DLR and GSF that simulate the parameters of space, such as vacuum, solar electromagnetic and cosmic ionizing radiation, temperature extremes and reduced gravity that can be applied separately, or in selected combinations. Such studies contribute to answer several questions pertinent to exobiology, such as the relevance of the delivery of extraterrestrial organic molecules to the Earth for the origin of life, the role of solar UV radiation in genetic stability, strategies of adaptation to environmental extremes, the probability and limits for interplanetary transfer of life, and the needs for planetary protection.

Mars 96 landers planetary protection implementation and planetary protection specifications for the upcoming ESA planetary missions

Abstract According to the article IX of the OUTER SPACE TREATY (London / Washington January 27., 1967), extraterrestrial missions should be conducted in a manner that protects the planets and the Earth from contamination. Consequently, COSPAR (Committee of Space Research) has established Planetary Protection recommendations 1 which are taken into account by all project teams involved in solar system exploration missions. The Mars 96 mission was launched in November 1996. Unfortunately, the mission failed a few hours after launch. Nevertheless, all tasks concerning Planetary Protection were accomplished before the launch of the spacecraft. Taking into account this experience, similar specifications have been developed by CNES for the Mars Express mission in which the anticipated involvement of CNES is the construction of small landers named Netlanders. Exobiological experiments are not foreseen at this time. It must be added that NASA and CNES are presently studying a common Mars sample return mission for 2005. In addition to the sample return module, CNES may also provide Netlanders with exobiological experiments. A final decision about this cooperation will be reached early in 1999. A brief status of Rosetta mission will also be included. For this mission, the DLR (Deutsches Gesellschaft fur Luft und Raumfahrt) provides a cometary lander including experiments and lander subsystems provided by CNES.

Synthesis of amino acids in Earth orbit: Proposal

Organic compounds in comets are of interest since they could be the sources of the terrestrial biosphere. They are supposed to be formed in an interstellar dust (ISD) environment. We performed laboratory simulation of the formation of bioorganic compounds in ISD environments: Amino acid precursors were detected in the products after ice mixture of CO (or CH 4, CH 3OH), NH 3 and H 2O. The present results should be confirmed in actual space conditions, such as in an exposed facility of JEM. We are designing an apparatus of such exobiology experiments in earth orbit (EEEO). Basic designs proposed for EEEO, remaining problems, and expected outcome will be discussed.

Exobiology missions proposed in Japan to utilize International Space Station

The Japanese portion of International Space Station offers opportunities to conduct exobiology experiments and observations at its exposed facility. Preparatory studies have been conducted to define proposals for its possible utilization. Research subjects have been proposed from quite diverse fields of exobiology. It ranges from a basic scientific mission, such as a survey on formation and fate of organic materials under space environment, to a part of an engineering project related to quarantine technology for planetary probes dedicated to exobiology exploration. Besides technical feasibility of implementation of those payloads on the space system, scientific assessment is strongly required to elucidate key issues of exobiology conducted in near Earth orbit. Even research facilities in low Earth orbit, although literally in space, give quite a different environment from that of interstellar space in many aspects. Scientific significance of conducting exobiology there should be based on uniqueness of employing microgravity and its synergetic effects with other factors for exobiology. Because of the quite limited chance of executing space experiments, as well as high cost of its execution, proposed subjects should be proved to possess great competitiveness against studies on the ground where space environment could also be well simulated with less cost. An international forum for exobiology might play an important role to formulate prioritized plan and strategy of the discipline. Such a body could orchestrate exobiology in Earth orbit under complementary relationships among scientific endeavors carried on by scientists who participate in collaborative efforts.

Abiotic formation of bioorganic compounds in space--preliminary experiments on ground and future exobiology experiments in space.

Simulation experiments on ground have shown that "amino acid precursors", which give amino acids after acid-hydrolysis, can be formed when an ice mixture simulating ice mantles of interstellar dust particles (lSDs) is irradiated with high energy particles or UV light. It is strongly suggested that such bioorganic compounds were delivered by comets for the first biosphere on the Earth. It is of great interest to confirm this hypothesis in actual space conditions, such as in an exposed facility of JEM. Fundamental designs for such exobiology experiments in earth orbit (EEEO) will be discussed.

Exobiological experiments in Earth orbit

The primary goal of exobiological research is to reach a better understanding of the processes leading to the origin, evolution and distribution of life on Earth or elsewhere in the universe. In this endeavour, scientists from a wide variety of disciplines are involved, such as astronomy, planetary research, organic chemistry, palaeontology and the various sub disciplines of biology. Space technology plays an important part by offering the opportunity for exploring our solar system, for collecting extraterrestrial samples, and for utilising the peculiar environment of space as a tool. Exobiological activities in Earth orbit include studies on the survival of resistant life forms in space. During previous space missions, such as Gemini, Spacelab, LDEF, Foton, MIR and EURECA, exposure of various microorganisms to selected and combined space conditions has demonstrated the enormous lethal potency of extraterrestrial solar UV radiation. However, when efficient shielding is provided against the influx of solar UV radiation, bacterial spores cope with space for more than 5 years without any loss of viability. Future research, e.g. on the space station by use of the SEBA facility, will provide clues towards our understanding of the relevance of extraterrestrial organic molecules to the emergence of life on Earth or any other planet, the role of solar UV radiation in evolutionary processes, related to life, the chances and limits for life to be transported from one body of our solar system to another or beyond, and of exobiological phenomena in aerosols and clouds.

Exobiology experiments in earth orbit: Results and perspectives for future research

Exobiology experiments in earth orbit: Results and perspectives for future research

Study of the Origin, Evolution and Distribution of Life with Emphasis on Exobiology Experiments in Earth Orbit

Publisher Summary This chapter presents an overview of those aspects of exobiology that can be investigated by experiments in earth orbit. The chapter focuses on the processes of organic chemical evolution in different bodies of solar system and beyond, and discusses the relevance of the organic compounds to the emergence of life on Earth. The possibility of interplanetary distribution of life is reviewed, and the experimental data testing this hypothesis is presented. In the chain of evolutionary steps towards the emergence of life, prebiotic chemical evolution is crucial. For the supply of organic molecules on the primitive earth, two plausible pathways are considered: terrestrial production of organics and import of extraterrestrial organic matter. In experiments simulating the putative conditions existing on the early earth, nearly all building blocks of life are synthesized, such as amino acids, purines, pyrimidines, and lipid-like compounds. However, in a non-reducing atmosphere, nitrogen containing compounds are unstable. Therefore, incoming extraterrestrial material may be considered as an essential source of organics on the primitive earth.

Earth analogs for Martian life. Microbes in evaporites, a new model system for life on Mars

The prospect of life on Mars today is daunting. Especially problematic for a potential life form is the lack of water, particularly in a liquid state; extremely cold temperatures; ultraviolet and ionizing radiation; and soil oxidants. Yet, “oases” where life might persist have been suggested to occur in rocks (in analogy with endolithic microorganisms described from deserts around the world), in polar ice caps (in analogy with snow and ice algae) and in possible volcanic regions (in analogy with chemoautotrophs living in deep sea hydrothermal vents); all are critically examined. Microorganisms are known to be able to survive in salt crystals, and recently it has been shown that organisms can metabolize while encrusted in evaporites. Because evaporites are thought to occur on Mars and can attenuate light in the UV range while being far more transparent to radiation useful for photosynthesis (400–700 nm), and because of the properties of these “endoevaporitic” organisms, I propose that such communities provide a new model system for studying potential life on Mars. On the basis of this model, I suggest possibilities for site selection for future exobiological experiments on Mars.

On performing exobiology experiments on an earth-orbital platform with the gas-grain simulation facility

Laboratory simulations of gas-dust interactions performed on Space Station Freedom in the Gas-Grain Simulation Facility (GGSF) are considered for studying the nature of bodies in the solar system. The GGSF includes a 4-10 liter chamber for experiments with the capability for environmental control, measurement, levitation, and energy. The simulations can provide low gas pressure and dust density in a microgravitational environment.

Microgravity particle research on the space station: The gas-grain simulation facility

In the gravitational field on Earth, the large settling rate of micron-sized particles and the effects of gravity-induced convection prohibit many interesting studies of phenomena such as coagulation, collisions, and mutual interactions of droplets, dust grains and other particles. Examples of exobiology experiments involving these phenomena are the simulation of organic aerosol formation in Titan's atmosphere, studies of the role of comets in prebiotic chemical evolution, and simulations of carbon grain interactions in various astrophysical environments. The Gas-Grain Simulation Facility (GGSF) is a proposed Earth-orbital laboratory that will allow present ground-based experimental programs which study processes involving small particles and weak interactions to be extended to a new domain. Physics issues that scientists wishing to propose GGSF experiments must consider are reviewed in this paper. Specifically, coagulation, motion in gases and vacua, and wall deposition of particles in a microgravity environment are discussed.

Gas chromatography for space research

Different chromatographic methods can be used in the process of studying various space objects. This paper reviews application possibilities of gas chromatography for space research, for instance, for detection of life on other plantes. Exobiological experiments using gas chromatography methods are described. Principle requirements chromatographs for space studies are reviewed.