Search

The possibility of biological transfer between planetary bodies is seldom factored into life detection strategies, although the actuality of such an event would have profound implications for how we interpret potential biosignatures found on other worlds. This article addresses the possibility of life on Mars in the context of a biological transfer and an independent genesis of life. The phylogenetic tree of life on Earth is used as a blueprint to interpret evidence of life and as a guideline to determine the likelihood that potential biosignatures could be expressed by martian organisms. Several transfer scenarios are considered, depending on the timing of transfer with respect to the evolution of life on Earth. The implications of each transfer scenario and an independent genesis of life on the biochemical nature of the resulting martian organisms are discussed. The analysis highlights how conceding the possibility of a biological transfer has practical implications for how we search for evidence of life, both in terms of the quality of potential biosignatures and the likelihood that certain biosignatures might be expressed. It is concluded that a degree of uncertainty on the origin of martian organisms might be unavoidable, particularly in the absence of a biochemical context.

On November 5–8, 2019, the “Mars Extant Life: What's Next?” conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia (“oases”), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques—that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

The success of an astrobiological search for life campaign on Mars, or other planetary bodies in the Solar System, relies on the detectability of past or present microbial life traces, namely, biosignatures. Spectroscopic methods require little or no sample preparation, can be repeated almost endlessly, and can be performed in contact or even remotely. Such methods are therefore ideally suited to use for the detection of biosignatures, which can be confirmed with supporting instrumentation. Here, we discuss the use of Raman and Fourier Transform Infrared (FT-IR) spectroscopies for the detection and characterization of biosignatures from colonies of the fungus Cryomyces antarcticus, grown on Martian analogues and exposed to increasing doses of UV irradiation under dried conditions. The results report significant UV-induced DNA damage, but the non-exceeding of thresholds for allowing DNA amplification and detection, while the spectral properties of the fungal melanin remained unaltered, and pigment detection and identification was achieved via complementary analytical techniques. Finally, this work found that fungal cell wall compounds, likely chitin, were not degraded, and were still detectable even after high UV irradiation doses. The implications for the preservation and detection of biosignatures in extraterrestrial environments are discussed.

Mars is a primary target of astrobiological interest: its past environmental conditions may have been favourable to the emergence of a prebiotic chemistry and, potentially, biological activity. In situ exploration is currently underway at the Mars surface, and the subsurface (2 m depth) will be explored in the future ESA ExoMars mission. In this context, BIOlogy and Mars EXperiment was performed to evaluate the stability and detectability of organic biomarkers under space and Mars-like conditions. Our data suggested that some target molecules, namely melanin, azelaic acid and nucleic acids, can be detected even after 16 months exposure to Low Earth Orbit conditions by multidisciplinary approaches. We used the same techniques as onboard the ExoMars rover, as Raman and infrared spectroscopies and gas chromatograph-mass spectrometer, and polymerase chain reaction even if this is not planned for the imminent mission to Mars. These results should be taken into account for future Mars exploration.

For the past fifty years of space exploration, mass spectrometry has provided unique chemical and physical insights on the characteristics of other planetary bodies in the Solar System. A variety of mass spectrometer types, including magnetic sector, quadrupole, time-of-flight, and ion trap, have and will continue to deepen our understanding of the formation and evolution of exploration targets like the surfaces and atmospheres of planets and their moons. An important impetus for the continuing exploration of Mars, Europa, Enceladus, Titan, and Venus involves assessing the habitability of solar system bodies and, ultimately, the search for life—a monumental effort that can be advanced by mass spectrometry. Modern flight-capable mass spectrometers, in combination with various sample processing, separation, and ionization techniques enable sensitive detection of chemical biosignatures. While our canonical knowledge of biosignatures is rooted in Terran-based examples, agnostic approaches in astrobiology can cast a wider net, to search for signs of life that may not be based on Terran-like biochemistry. Here, we delve into the search for extraterrestrial chemical and morphological biosignatures and examine several possible approaches to agnostic life detection using mass spectrometry. We discuss how future missions can help ensure that our search strategies are inclusive of unfamiliar life forms.

There has been considerable attention on how to detect life on other worlds by searching for biomolecules. However, there has been much less clarity as to when it becomes warranted to focus a mission on the search for life on another world. At a minimum, a life-detection mission should follow convincing evidence of (1) Liquid water of suitable salinity, past or present; (2) Carbon in the water; (3) Biologically available N in the water; (4) Biologically useful energy in the water; (5) Organic material that can possibly be of biological origin and a plausible strategy for sampling this material. Based on these prerequisites, the most promising targets for a life search are currently the plume of Enceladus and the subsurface of Mars-in equatorial lake bed sediments and in polar ice-cemented ground. Neither the surface of Europa nor the clouds of Venus meet the criteria listed here but may with further exploration.

Answering the question of whether life ever existed on Mars is a key goal of both NASA's and ESA's imminent Mars rover missions. The obfuscatory effects of oxidizing salts, such as perchlorates and sulfates, on organic matter during thermal decomposition analysis techniques are well established. Less well studied are the transformative effects of iron oxides and (oxy)hydroxides, which are present in great abundances in the martian regolith. We examined the products of flash pyrolysis-gas chromatography-mass spectrometry (a technique analogous to the thermal techniques employed by past, current, and future landed Mars missions) which form when the cyanobacteria Arthrospira platensis are heated in the presence of a variety of Mars-relevant iron-bearing minerals. We found that iron oxides/(oxy)hydroxides have transformative effects on the pyrolytic products of cyanobacterial biomolecules. Both the abundance and variety of molecular species detected were decreased as iron substrates transformed biomolecules, by both oxidative and reductive processes, into lower fidelity alkanes, aromatic and aryl-bonded hydrocarbons. Despite the loss of fidelity, a suite that contains mid-length alkanes and polyaromatic hydrocarbons and/or aryl-bonded molecules in iron-rich samples subjected to pyrolysis may allude to the transformation of cyanobacterially derived mid-long chain length fatty acids (particularly unsaturated fatty acids) originally present in the sample. Hematite was found to be the iron oxide with the lowest transformation potential, and because this iron oxide has a high affinity for codeposition of organic matter and preservation over geological timescales, sampling at Mars should target sediments/strata that have undergone a diagenetic history encouraging the dehydration, dihydroxylation, and oxidation of more reactive iron-bearing phases to hematite by looking for (mineralogical) evidence of the activity of oxidizing, acidic/neutral, and either hot or long-lived fluids.

The search for molecular biosignatures at the surface of Mars is complicated by an intense irradiation in the mid- and near-ultraviolet (UV) spectral range for several reasons: (i) many astrobiologically relevant molecules are electronically excited by efficient absorption of UV radiation and rapidly undergo photochemical reactions; (ii) even though the penetration depth of UV radiation is limited, aeolian erosion continually exposes fresh material to radiation; and (iii) UV irradiation generates strong oxidants such as perchlorates that can penetrate deep into soils and cause subsurface oxidative degradation of organics. As a consequence, it is crucial to investigate the effects of UV radiation on organic molecules embedded in mineral matrices mimicking the martian soil, in order to validate hypotheses about the nature of the organic compounds detected so far at the surface of Mars by the NASA Mars Science Laboratory’s (MSL) Curiosity rover, as well as organics that will be possibly found by the next rover missions Mars 2020 (NASA) and ExoMars 2022 (ESA-Roscosmos). In addition, studying the alteration of possible molecular biosignatures in the martian environment will help to redefine the molecular targets for life detection missions and devise suitable detection methods. Here we report the results of mid- and near-UV irradiation experiments of Mars soil analog samples obtained adsorbing relevant organic molecules on a clay mineral that is quite common on Mars, i.e. montmorillonite, doped with 1 wt% of magnesium perchlorate. Specifically, we chose to investigate the photostability of a plausible precursor of the chlorohydrocarbons detected on Mars by the Curiosity rover, namely phthalic acid, along with the biomarkers of extant life L-phenylalanine and L-glutamic acid, which are proteomic amino acids, and adenosine 5’-monophosphate, which is a nucleic acid component. We monitored the degradation of these molecules adsorbed on montmorillonite through in situ spectroscopic analysis, investigating the reflectance properties of the samples in the Near InfraRed (NIR) spectral region. Such spectroscopic characterization of molecular alteration products provides support for two upcoming robotic missions to Mars that will employ NIR spectroscopy to look for molecular biosignatures, through the instruments SuperCam on board Mars 2020, ISEM, Ma_Miss and MicrOmega on board ExoMars 2022.

Unravelling how long life can persist under extreme dryness and what kind of environmental extremes can be faced by dried microorganisms, is relevant to understand Mars habitability and to search for life on planets with transient liquid water availability. Since trehalose and sucrose stabilize dried anhydrobiotes, an in silico survey of the genome of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was performed to identify pathways for trehalose and sucrose biosynthesis. The expression of the identified genes was induced in response to desiccation and trehalose and sucrose accumulation was detected in dried cells. This adaptation strategy enabled viability and biomarker permanence under extreme dryness and Mars-like UV flux. Chroococcidiopsis survivors were scored in 7-year dried biofilms mixed with phyllosilicatic Mars regolith simulant and exposed to 5.5 x 103 kJ/m2 of a Mars-like UV flux. No survivors occurred after exposure to 5.5 x 105 kJ/m2, although in dead cells, photosynthetic pigments and nucleic acids, both DNA and RNA, were still detectable. This suggested that dried biofilms mixed with phyllosilicatic Martian regolith simulant are suitable candidates to identify biosignatures embedded in planetary analogue minerals as planned in the future BioSigN (BioSignatures and habitable Niches) space mission to be performed outside the International Space Station.

The growing scientific interest in the “virus first hypothesis” (VFH) as an early step in the origin of life has practical implications for searches and life detection on future Mars missi...

著者人数: 13名, Accepted: 2017-10-12, 資料番号: SA1180309000

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars—Mass spectrometry—Life detection—Planetary instrumentation. Astrobiology 17, 655–685., Table of Contents 1. Introduction: The Mars Organic Molecule Analyzer (MOMA) Investigation 2. Science Goals 3. Objectives and Requirements 4. Instrument Top-Level Description 5. Instrument Development 5.1. Team organization 5.2. Instrument integration flow 5.3. Instrument verification 5.4. Achieved milestones and deliveries 6. Instrument Subsystems 6.1. Oven and tapping station subsystems 6.1.1. Derivatization 6.1.1.1. MTBSTFA 6.1.1.2. DMF-DMA 6.1.2. Thermochemolysis 6.1.3. Wet chemistry: storage and release of chemical agents 6.2. Gas chromatograph subsystem 6.2.1. Design requirements 6.2.2. Design overview 6.2.2.1. General architecture 6.2.2.2. Injection system 6.2.2.3. Separation of volatiles 6.2.2.4. Detection of volatiles 6.2.2.5. Gas handling system 6.2.2.6. GCMS coupling campaigns 6.3. Laser subsystem 6.3.1. Design requirements 6.3.2. Laser architecture 6.3.3. Verification data 6.4. Mass spectrometer subsystem 6.4.1. Design requirements 6.4.2. Analyzer architecture 6.4.2.1. Linear Ion Trap assembly 6.4.2.2. Detection channels 6.4.2.3. Electron Ionization Source 6.4.2.4. Fast-actuating aperture valve 6.4.2.5. Micropirani pressure sensor 6.4.2.6. Wide-Range Pump 6.4.3. Temperature control 6.4.4. Driving electronics 7. Operation of MOMA on the Surface of Mars 7.1. Expected measurement scenarios 7.2. Sequenced operational modes 7.3. Synergy with other instruments 7.3.1. Data interpretation 7.4. LDMS operations on Mars and test experiments on LDMS prototype system 7.5. Test experiments on GCMS prototype system: a case study 7.5.1. Sample and setup 7.5.2. Methods 7.5.2.1. Stepwise pyrolysis 7.5.2.2. Derivatization/thermochemolysis 7.5.2.3. GCMS parameters 7.5.3. Results and discussion 7.5.3.1. Pyrolysis 7.5.3.2. Derivatization and thermochemolysis 8. Discussion 9. Summary Acknowledgments Author Disclosure Statement References Abbreviations Used

No instrument capable of direct life detection has been included on a mission payload to Mars since NASA's Viking missions in the 1970s. This prevents us from discovering whether life is or ever was present on Mars. DNA is an ideal target biosignature since it is unambiguous, nonspecific, and readily detectable with nanopore sequencing. Here, we present a proof-of-concept utilization of the Oxford Nanopore Technologies (ONT) MinION sequencer for direct life detection and show how it can complement results from established space mission instruments. We used nanopore sequencing data from the MinION to detect and characterize the microbial life in a set of paleochannels near Hanksville, UT, with supporting data from X-ray diffraction, reflectance spectroscopy, Raman spectroscopy, and Life Detector Chip (LDChip) microarray immunoassay analyses. These paleochannels are analogs to martian sinuous ridges. The MinION-generated metagenomes reveal a rich microbial community dominated by bacteria and containing radioresistant, psychrophilic, and halophilic taxa. With spectral data and LDChip immunoassays, these metagenomes were linked to the surrounding Mars analog environment and potential metabolisms (e.g., methane production and perchlorate reduction). This shows a high degree of synergy between these techniques for detecting and characterizing biosignatures. We also resolved a prospective lower limit of ∼0.001 ng of DNA required for successful sequencing. This work represents the first determination of the MinION's DNA detection limits beyond ONT recommendations and the first whole metagenome analysis of a sinuous ridge analog., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Sulfate and iron oxide deposits in Río Tinto (Southwestern Spain) are a terrestrial analog of early martian hematite-rich regions. Understanding the distribution and drivers of microbial life in iron-rich environments can give critical clues on how to search for biosignatures on Mars. We simulated a robotic drilling mission searching for signs of life in the martian subsurface, by using a 1m-class planetary prototype drill mounted on a full-scale mockup of NASA's Phoenix and InSight lander platforms. We demonstrated fully automated and aseptic drilling on iron and sulfur rich sediments at the Río Tinto riverbanks, and sample transfer and delivery to sterile containers and analytical instruments. As a ground-truth study, samples were analyzed in the field with the life detector chip immunoassay for searching microbial markers, and then in the laboratory with X-ray diffraction to determine mineralogy, gas chromatography/mass spectrometry for lipid composition, isotope-ratio mass spectrometry for isotopic ratios, and 16S/18S rRNA genes sequencing for biodiversity. A ubiquitous presence of microbial biomarkers distributed along the 1m-depth subsurface was influenced by the local mineralogy and geochemistry. The spatial heterogeneity of abiotic variables at local scale highlights the importance of considering drill replicates in future martian drilling missions. The multi-analytical approach provided proof of concept that molecular biomarkers varying in compositional nature, preservation potential, and taxonomic specificity can be recovered from shallow drilling on iron-rich Mars analogues by using an automated life-detection lander prototype, such as the one proposed for NASA's IceBreaker mission proposal., Spanish Ministry of Science, Innovation and Universities and Fondo Europeo de Desarrollo Regional (MICINN/FEDER) projects No. CGL2015-74254-JIN, ESP2015-69540-R, and RYC-2014-19446; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Though Mars is a cold and dry planet now, Mars would have harbored a large amount of liquid water on the surface early in its history. Mars could have been similar to the early Earth from which life arose 4 billion years ago, and life may have also emerged on Mars during this period. Although the Viking mission in 1976, which explored life on Mars, did not find evidence for life, many findings associated with the possibility of life have been discovered since the Viking mission: past and present aqueous environments, organic compounds, methane, reduced compounds suitable for microorganism energy sources, and so on. These findings suggest that life might exist on Mars. Habitable environments may be deep subsurface, but it may also be on or near the surface where physical and chemical conditions on which even terrestrial microorganisms to survive are found. Life detection instruments have been developed since the Viking mission. Traces or existence of Martian life might be found by future exploration.

Humanity's interest in whether or not we are alone in the universe spans generations, from Giordano Bruno's 16th century musings on other worlds and Giovanni Schiaparelli reporting seeing ‘canali’ in 1877 on the surface of Mars (which were thought to have been created by intelligent life) to alien invasions portrayed in today's movies. However, it is still unclear if other planetary bodies are capable of supporting life. In the search for life there are two broad areas we look into, the requirements of life and actual signs of life. The identification of the key requirements for life enables scientists to focus life detection efforts onto planets and satellites that are considered habitable and more likely to support life. However, our ability to find life or detect signs of life is based on our understanding of life on Earth.

The ExoMars 2020 MOMA (Mars Organic Molecule Analyzer) Gas Chromatograph Mass Spectrometer instrument is a key component of the Pasteur life detection payload on the ExoMars 2020 rover mission. As such it is subject to Planetary Protection requirements which include being sufficiently contamination controlled to preclude false positive or false negative results due to contamination. Detailed evaluation of the interaction instrument background and the other performance attributes of the Gas Chromatograph Mass Spectrometer during testing under Mars like conditions of temperature and pressure was carried out. This was the first test of the fully integrated test of the Gas Chromatograph Mass Spectrometer. The data from the testing was evaluated in four different modes of data analysis commonly used for processing gas chromatograph mass spectrometer data. This analysis showed that the instrument was capable of meeting its detection limit requirements. The analysis of the data also showed that the probability of false positives and false negatives within the specified instrument performance capabilities was minimal as evaluated at this time.

The ExoMars 2020 Rover is a life detection mission, and is classified as Planetary Protection (PP) Mission Category IVb, the first IVb mission since the Viking missions. Mars Organic Molecule Analyzer – Mass Spectrometer (MOMA-MS) is a life detection instrument for the rover. To meet the stringent bioburden requirement of 0.03 spore/m2, the MS is subjected to Dry Heat Microbial Reduction (DHMR) to decrease the bioburden from a measured 88 spores/m2 to 0.009 spores/m2. After DHMR, exposure of the sample path must be kept to an absolute minimum and requires aseptic operations. Aseptic operations include determining the safe exposure time based on the surface area of exposure and particle fallout expected in the aseptic ISO class 5 workspace, preparing an aseptic ISO class 5 workspace, and using sterile garments and tools. During the exposure activity the environment is monitored with active and passive fallout for bioburden and real time airborne particle counts. Sterile tools are handled by a two person team so the operator touches only the tool and not the exterior surfaces of the sterilization pouch, and a sterile operating field is established as a safe place to organize tools or parts during the aseptic operations. In cases where aseptic operations are not feasible, localized DHMR is used after exposure. Any breach in the PP cleanliness can necessitate repeating instrument level DHMR, which not only has significant cost and schedule implications, but also is a risk to hardware that is not rated for repeated long exposures to high temperatures.

In this chapter we will elaborate on how evidence for life on other worlds can be sought, and if present, possibly detected. The best evidence for extraterrestrial life, of course, would be recovery of actual specimens or their fossils. For the next one or two decades, the possibility of obtaining such direct evidence is almost surely restricted to samples from Mars and Venus, and possibly from some moons of the outer Solar System such as Europa and Enceladus. So detection of life beyond our nearest neighbors will be dependent for the near future on remote sensing. As technology of robotic exploration and remote sensing improves, the possibility of detecting extraterrestrial life will grow. While the size of individual organisms makes their detection at a distance virtually impossible, organisms in the aggregate alter their environments, generating signatures of their functional processes. These direct consequences of biological activity are referred to as “biosignatures”. Other effects of the presence of living systems may be detected in global or geological features. These alterations of the geological environment due to life processes, we call “geosignatures”. Even on worlds too remote, small, or difficult for whatever reason to monitor for the existence of explicit signatures of life, certain planetary characteristics can be detected that are more likely to be consistent with the presence of life than others. These we refer to as “geoindicators.” They consist of parameters that are consistent with life as defined in Chap. 2, and the requirements for life as described in subsequent chapters, including a flow or gradient of energy, presence of an appropriate solvent, and availability of complex polymeric chemistry. While geoindicators point to the potential for supporting life, they do not confirm its existence. Most geoindicators can be detected by remote sensing methods with relative ease, however, and thus can be used in assessing the plausibility of the existence of life. At the end of the chapter, we apply our discussion of signatures and indicators of life to assess the relative plausibility for the existence of life on other bodies in our Solar System. How to detect and confirm living processes with life detection experiments will be discussed in Chap. 10.

The first step in many life detection protocols on Mars involves attempts to extract or isolate organic matter from its mineral matrix. A number of extraction options are available and include heat and solvent assisted methods. Recent operations on Mars indicate that heating samples can cause the loss or obfuscation of organic signals from target materials, raising the importance of solvent-based systems for future missions. Several solvent types are available (e.g. organic solvents, surfactant based solvents and subcritical water extraction) but a comparison of their efficiencies in Mars relevant materials is missing. We have spiked the well characterised Mars analogue material JSC Mars-1 with a number of representative organic standards. Extraction of the spiked JSC Mars-1 with the three solvent methods provides insights into the relative efficiency of these methods and indicates how they may be used on future Mars missions.

The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg−1) and perchlorate (41.13 μg g−1 maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g−1) or formate (76.06 μg g−1) as electron donors, and sulfate (15875 μg g−1), nitrate (13490 μg g−1), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars. Key Words: Atacama Desert—Life detection—Biosensor—Biopolymers—In situ measurement. Astrobiology 11, 969–996.

Terrestrial analogue environments are places on Earth that present geological or environmental conditions that are similar to those found on an extraterrestrial body. Analogue environments serve four functions: (1) learn about planetary processes on Earth and elsewhere; (2) test technologies, methodologies, and protocols; (3) train highly-qualified personnel, as well as science and operations teams; (4) engage the public, space agencies, media, and educators. Analogue studies also enable the development and validation of biosignatures and detection techniques. Analogue programs include the Canadian Space Agency's Canadian Analogue Research Network, NASA's Astrobiology Science and Technology for Exploring Planets, and NASA's Analog Missions. Examples of technology and instrument testing and validation in analogue environments include the Haughton-Mars Project Research Station, the Arctic Mars Analog Svalbard Expedition (AMASE), the Rio Tinto basin, and NASA's Field Integrated Design and Operations (FIDO).

Two alternative hypotheses explain the degradation of organics in the Viking Labeled Release experiment on Mars. Either martian soil contains live indigenous microorganisms or it is sterile but chemically reactive. These two possibilities could be distinguished by the use of pure preparations of glucose isomers. In the laboratory, selected eukaryotes, bacteria, and archaea consumed only D-glucose, not L-glucose, while permanganate oxidized both isomers. On Mars, selective consumption of either D- or L-glucose would constitute evidence for biological activity.

Field expeditions that simulate the operations of robotic planetary exploration missions at analog sites on Earth can help establish best practices and are therefore a positive contribution to the planetary exploration community. There are many sites in Iceland that possess heritage as planetary exploration analog locations and whose environmental extremes make them suitable for simulating scientific sampling and robotic operations. We conducted a planetary exploration analog mission at two recent lava fields in Iceland, Fimmvorðuhals (2010) and Eldfell (1973), using a specially developed field laboratory. We tested the utility of in-field site sampling down selection and tiered analysis operational capabilities with three life detection and characterization techniques: fluorescence microscopy (FM), adenine-triphosphate (ATP) bioluminescence assay, and quantitative polymerase chain reaction (qPCR) assay. The study made use of multiple cycles of sample collection at multiple distance scales and field laboratory analysis using the synchronous life-detection techniques to heuristically develop the continuing sampling and analysis strategy during the expedition. Here we report the operational lessons learned and provide brief summaries of scientific data. The full scientific data report will follow separately. We found that rapid in-field analysis to determine subsequent sampling decisions is operationally feasible, and that the chosen life detection and characterization techniques are suitable for a terrestrial life-detection field mission. In-field analysis enables the rapid obtainment of scientific data and thus facilitates the collection of the most scientifically relevant samples within a single field expedition, without the need for sample relocation to external laboratories. The operational lessons learned in this study could be applied to future terrestrial field expeditions employing other analytical techniques and to future robotic planetary exploration missions.

A large number of missions are scheduled, particularly on Mars, in order to search for life or traces of past life. Taking into account CNES past experience in planetary protection related to the Mars 96 mission 4,5,6 , its planned participation in exobiological missions with NASA as well as its works and involvement in Cospar activities, the paper will give the main requirements in order to avoid celestial bodies biological contamination, including Earth, and to protect exobiological science. For ethical, safety and scientific reasons, the space agencies have to respect the article IX of the Outer Space Treaty (London / Washington January 27., 1967) and consequently to comply with the related COSPAR planetary protection recommendations. The goal is to protect target planets from Earth microbiological contamination and also to protect Earth environment from an eventual biocontamination coming from extraterrestrial samples or carried by contaminated sample return probes. Planetary protection takes also into account the protection of exobiological science. The validation of its results depends strongly of the biological and organic chemical cleanliness of samples, and more generally of how the samples have been preserved. Take into account such requirements gives to project teams specifications for equipement or probe sterilization, microbiological controls, special integration procedures, recontamination avoidance, …etc, needing specific and unusual implementations. One of CNES present interest is focussed on exobiological missions, including sample return missions 7 , as well as works and involvement in COSPAR activities linked to planetary protection. The search of life, organic molecules or compounds related to life imposes harder biological and organic cleanliness specifications, associated with constraints for sample preservation, in order to avoid any mistake or doubt on scientific results. Biological and organic cleanliness is probably the main constraint, but function of where and how the samples are collected, confined, transported and analyzed could have effects on samples characteristics.

The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions “what to look for”, “where to look”, and “how to look for it” require more of our attention to ensure the success of future life detection missions on Mars.

Special regions are locations onMars that could be hospitable for Earth life or be a habitat for Martian life. Currently, special regions are defined using the parameters of temperature and water activity. The specification as of 2010 is a location where the temperature reaches above 25 C and the water activity is above 0.5 (relative humidity above 50 %). According with the planetary protection policy edited by the COSPAR, these special regions define a new category (Category IVc) of Martian mission. For those missions which investigate Martian special regions, even if they do not include life detection experiments, all of the requirements applicable to the a mission aiming at the surface of Mars (Category IVa) apply, along with the following requirements

Curiosity’s latest reported findings, or lack thereof, are interpreted from the standpoint of their implications for the Viking Labeled Release experiment, and for life on Mars in general. As of the writing of this abstract, Curiosity has reported no findings related to those anticipated by the author’s last year’s paper, “Stealth Life Detection Experiments Aboard Curiosity.” However, Curiosity scientists have stated that soil and rock samples have been taken and analyzed, and abundant images have been downloaded. The only (indirectly) relevant reports issued by Curiosity scientists concern small-molecule organics found in a soil sample, which simple compounds they suggest might be terrestrial contamination, and images of rocks with colored (green) patches, the latter not of sufficient resolution (of which the cameras are capable) to detect possible evidence of biology. Hopefully, by the time of preparation of the body of this paper, more information will be available.

Widespread organic synthesis in the early solar nebula led to delivery of similar complex organics, probably including nucleobases or their precursors, to many potentially habitable locations such as Mars, Europa, and Enceladus. If life evolved beyond Earth, the presence of these organics could have biased life towards utilization of informational polymers (IPs) like RNA or DNA. Given this, searching for and sequencing any such IPs offers a definitive, information rich, approach to life detection that complements existing methods. Saturn's icy moon Enceladus offers possibly the best conditions in the solar system to find extant life beyond Earth. Recent discovery of a salt-water plume likely derived from sub-surface liquid reservoirs provides direct access to this potentially habitable environment. We describe an instrument concept, the Enceladus Orbiting Sequencer (EOS), specifically geared to search for life on Enceladus. As a payload on board an Enceladus flyby or orbiter mission, EOS would capture ice grains from the plume, then concentrate and characterize any long charged polymers using nanopore or semiconductor sequencing. Searching for life on Enceladus could give us our first glimpse of a second genesis and test whether biochemistry is varied or universal.

NASA has often stated (e.g. MSL Science Corner1) that it’s Mars Science Laboratory (MSL), “Curiosity,” Mission to Mars carries no life detection experiments. This is in keeping with NASA’s 36-year explicit ban on such, imposed immediately after the 1976 Viking Mission to Mars. The space agency attributes the ban to the “ambiguity” of that Mission’s Labeled Release (LR) life detection experiment, fearing an adverse effect on the space program should a similar “inconclusive” result come from a new robotic quest. Yet, despite the NASA ban, this author, the Viking LR Experimenter, contends there are “stealth life detection instruments” aboard Curiosity. These are life detection instruments in the sense that they can free the Viking LR from the pall of ambiguity that has held it prisoner so long. Curiosity’s stealth instruments are those seeking organic compounds, and the mission’s high-resolution camera system. Results from any or all of these devices, coupled with the Viking LR data, can confirm the LR’s life detection claim. In one possible scenario, Curiosity can, of itself, completely corroborate the finding of life on Mars. MSL has just successfully landed on Mars. Hopefully, its stealth confirmations of life will be reported shortly.

Several robotic exploration missions will travel to Mars during this decade to investigate habitability and the possible presence of life. Field research at Mars analogue sites such as desert environments can provide important constraints for instrument calibration, landing site strategies and expected life detection targets. We have characterized the mineralogy, organic chemistry and microbiology of ten selected sample sites from the Utah desert in close vicinity to the Mars Desert Research Station (MDRS) during the EuroGeoMars 2009 campaign (organized by International Lunar Exploration Working Group (ILEWG), NASA Ames and ESA ESTEC). Compared with extremely arid deserts (such as the Atacama), organic and biological materials can be identified in a larger number of samples and subsequently be used to perform correlation studies. Among the important findings of this field research campaign are the diversity in the mineralogical composition of soil samples even when collected in close proximity, the low abundances of detectable polycyclic aromatic hydrocarbons (PAHs) and amino acids and the presence of biota of all three domains of life with significant heterogeneity. An extraordinary variety of putative extremophiles, mainly Bacteria and also Archaea and Eukarya was observed. The dominant factor in measurable bacterial abundance seems to be soil porosity and lower small (clay-sized) particle content. However, correlations between many measured parameters are difficult to establish. Field research conducted during the EuroGeoMars 2009 campaign shows that the geological history and depositional environment of the region, as well as the mineralogy influence the ability to detect compounds such as amino acids and DNA. Clays are known to strongly absorb and bind organic molecules often preventing extraction by even sophisticated laboratory methods. Our results indicate the need for further development and optimization of extraction procedures that release biological compounds from host matrices to enable the effective detection of biomarkers during future sampling campaigns on Earth and Mars.

Near-future planetary missions, including the US 2011 Mars Science Laboratory (MSL11) and the ESA 2016 Pasteur ExoMars, will primarily seek key information on the geological and biological history of Mars. In this context, studies addressing the potential for (1) preservation of organics and (2) habitability and microbial ­biomass in phyllosilicate-rich and ferric oxide-rich environments can provide key interpretive ­information for near-future Mars Science/life detection missions.

Organic minerals, organic acids and NH-containing organic molecules represent important target molecules for astrobiology. Here, we present the results of the evaluation of a portable hand-held Raman spectrometer to detect these organic compounds outdoors under field conditions. These measurements were carried out during the February–March 2009 winter period in Austrian Alpine sites at temperatures ranging between −5 and −25 ° C. The compounds investigated were detected under field conditions and their main Raman spectral features were observed unambiguously at their correct reference wavenumber positions. The results obtained demonstrate that a miniaturized Raman spectrometer equipped with 785 nm excitation could be applied with advantage as a key instrument for investigating the presence of organic minerals, organic acids and nitrogen-containing organic compounds outdoors under terrestrial low-temperature conditions. Within the payload designed by ESA and NASA for several missions focusing on Mars, Titan, Europa and other extraterrestrial bodies, Raman spectroscopy can be proposed as an important non-destructive analytical tool for the in situ identification of organic compounds relevant to life detection on planetary and moon surfaces or near subsurfaces.

Well-resolved Raman spectra of organic acids were obtained with 785 nm excitation using a portable Raman instrument (Ahura First Defender XL) under low temperature −5 °C atmospheric conditions at an altitude of 2000 m (Axamer Lizum, Innental, Austria). The portable Raman spectrometer tested in this setting permits fast and unambiguous detection of solid forms of these organic acids (formic, acetic, valeric, hexanoic, heptanoic, isophthalic, ascorbic and mellitic) under field conditions. This demonstrates the possibility to use a miniaturized Raman spectrometer as a key instrument for investigating the presence of organic compounds and biomolecules under low temperature conditions. These results are important for future missions focusing not only on Mars, where Raman spectroscopy will be a key non-destructive analytical tool for the in situ identification of organic compounds relevant to life detection on planetary surfaces or near sub-surfaces. Copyright © 2009 John Wiley & Sons, Ltd.

Analytical approaches to extant and extinct life detection involve molecular detection often at trace levels. Thus, removal of biological materials and other organic molecules from the surfaces of devices used for sampling is essential for ascertaining meaningful results. Organic decontamination to levels consistent with null values on life-detection instruments is particularly challenging at remote field locations where Mars analog field investigations are carried out. Here, we present a seven-step, multi-reagent decontamination method that can be applied to sampling devices while in the field. In situ lipopolysaccharide detection via low-level endotoxin assays and molecular detection via gas chromatography-mass spectrometry were used to test the effectiveness of the decontamination protocol for sampling of glacial ice with a coring device and for sampling of sediments with a rover scoop during deployment at Arctic Mars-analog sites in Svalbard, Norway. Our results indicate that the protocols and detection technique sufficiently remove and detect low levels of molecular constituents necessary for life-detection tests.

In the time since the Viking life-detection experiments were conducted on Mars, many missions have enhanced our knowledge about the environmental conditions on the Red Planet. However, the martian surface chemistry and the Viking lander results remain puzzling. Nonbiological explanations that favor a strong inorganic oxidant are currently favored (e.g., Mancinelli, 1989; Plumb et al., 1989; Quinn and Zent, 1999; Klein, 1999; Yen et al., 2000), but problems remain regarding the lifetime, source, and abundance of that oxidant to account for the Viking observations (Zent and McKay, 1994). Alternatively, a hypothesis that favors the biological origin of a strong oxidizer has recently been advanced (Houtkooper and Schulze-Makuch, 2007). Here, we report on laboratory experiments that simulate the experiments to be conducted by the Thermal and Evolved Gas Analyzer (TEGA) instrument of the Phoenix lander, which is to descend on Mars in May 2008. Our experiments provide a baseline for an unbiased test for chemical versus biological responses, which can be applied at the time the Phoenix lander transmits its first results from the martian surface.

Is there life on Mars? This is a major question within the scientific community and one that also has broad appeal within the general community. To date, only three missions have attempted to look for life on Mars—the two NASA Viking missions in the mid-1970s and the recent UK-led Beagle 2 mission. In all cases no life was detected—in the case of Beagle 2 due to a nonnominal landing event. Our current view of Mars is that historically there was the potential for life to have existed in the Maritain environment and even the possibility of there being current life on Mars. New analytical techniques are therefore being considered for the next generation of Mars rovers and landers to search for evidence of such life. Biosensors in the form of antibody microarray devices are being considered by a number of groups as potential instruments to detect evidence of life in situ in the form of molecular biomarkers within the Martian surface and near subsurface. Such research is at an early stage of development within the context of development of flight-qualified instrumentation. Given the extreme environments that will be encountered during various phases of a typical Mars mission, careful consideration of the effect of radiation exposure, instrument sterilization, minimization of instrument contamination, long-term storage, and various thermal environments will be required in instrument development programmes. It is hoped that pushing the development of biosensor technology for life detection in a planetary exploration context will allow both the eventual answer of a fundamental question within society and also provide new developments and approaches that will benefit existing biosensor developments in other areas of application. Keywords: astrobiology; immunosensor; antibody arrays; life on Mars

NASA has an aggressive plan for exploring Mars. Future in situ life detection and sample return missions will rely on clean and effectively sterile spacecraft to ensure reliable, valid science measurements. These spacecraft levy substantial requirements for planetary protection. Here, we report the results of a comparative analysis of the efficacy of three different cleaning approaches to remove bacterial spores from a series of surrogate spacecraft materials, parts, as well as cleaning challenging structures. The purpose of this study is to identify cleaning methods that achieve a minimum of a 4-log reduction of bioburden from inoculated surfaces. We believe that surfaces efficiently cleaned do not transfer biological particles, particularly spores, which when placed in close proximity with other materials become "effectively sterile." Our results indicate that a novel cleaning method, which utilize vacuum cycle nucleation (VCN) enabled technologies, can effectively remove bacterial spores from surrogate spacecraft material coupons, piece parts and structures. This cleaning technology may be a potential candidate for sterilizing Mars Lander systems, reducing the cost, risk, and material constraints encumbered by use of dry heat sterilization and common cleaning practices.

The Viking missions to Mars landed in two areas of the northern plains, at Chryse Plani-tia (22.5° N, 48° W) and Utopia Planitia (48° N, 226° W). Onboard the twin landers wereBiology Instruments, containing three separate experiments: the Gas-Exchange (GeX), Py-rolytic Release (PR) and Labeled Release (LR) experiments. In addition, there was a soilanalyzer based on X-ray Fluorescence Spectrometry (XRFS) to detect the concentrationof elements in samples and, most importantly, a Gas Chromatograph / Mass Spectrometer(GCMS) specifically designed to measure organic compounds in the soil. Together, theseinstruments were used to assay soils on Mars for biological activity, the presence of organiccompounds, and the bulk elemental composition of soils.

[1] The science goals of the Life in the Atacama (LITA) robotic field experiment are to understand habitat and seek out life in the Atacama Desert, Chile, as an analog to future missions to Mars. To those ends, we present a new data analysis tool, the LITA Data Scoring System (DSS), which (1) integrates rover and orbital data relevant to environmental habitability and life detection, and (2) provides a standard metric, or “score” to evaluate (a) the potential habitability, and (b) the strength of evidence for life at all locales along the rover's traverse. Designed and tested during the 2005 field campaign, first results from the DSS indicate that the three selected sites in the Atacama Desert are generally inhospitable. The strength of evidence for life is positively correlated with potential habitability at two of the three sites. Using factor analysis, we find three factors explain 79.9% of the variance in biological observations and five factors explain 96.2% of the variance in potential habitability across all sites. These factors are used to focus a discussion of scoring variable definitions for future robotic missions in the Atacama and of instrument selection and strategy development for future robotic missions on Earth and Mars.

Few, if any, major scientific quests have taken such frequent, diametrically opposed changes in prospect and direction as has the search for life on Mars. The erratic courses and their supporting rationales are traced: from Percival Lowell's astonishing pronouncement of intelligent beings on the red planet; to their denouement by Mariner 4; to the strong contraindications of any form of Martian life relayed by Mariners 6 and 7; to the discovery of a different, perhaps once-habitable, Mars revealed by the detailed orbital images, including the first evidence of ancient rivers, taken by Mariner 9; to the still-controversial claim of the detection of microbial life by the 1976 Viking Missions; to NASA's subsequent prohibition against any Mars life detection experiments; to the recently emerged consensus, propelled by findings of Pathfinder, the Mars Exploratory Rovers and the continuing discoveries of life in extreme environments on Earth, that past or extant life on Mars is likely. Against this background, the future Mars missions' experiments bearing on the life issue are reviewed. The case is made that none of these experiments, as currently planned, still subject to the prohibition against direct life detection experiments, can resolve this paramount and fundamental question that bears so heavily on the origin and distribution of life, and our place in the universe.

An integrated, miniaturized, low-power instrument capable of the detection and early characterization of microbial life in the soil of mars is proposed. Based on the detection and monitoring of ongoing metabolism as being the surest evidence for extant life, the experiments will probe for chirality in metabolism, for circadian rhythmicity, and for photosynthesis. However, the instrument package will also be able to detect biosignatures and a variety of other physical and chemical parameters of the Martian surface that have significance for life. These include the presence and the physical state of water, the existence of an oxidant, the pH and the penetrability of the soil. Using the legacy of the 1976 Viking labeled release (LR) life detection experiment in conjunction with state-of-the-art laser diode spectral analysis, the instrument can be flown stand-alone, with or without a rover, or as part of a mars science laboratory (MSL)-type mission. Sterility for experiment integrity and for planetary protection is provided.

There is growing evidence for ice and fluids near the surface of Mars with potential discharge of brines, which may preserve a record of past life on the planet. Proven techniques to sample Mars subsurface will be critical for future NASA astrobiology missions that will search for such records.

Earth's subsurface offers one of the best possible sites to search for microbial life and the characteristic lithologies that life leaves behind. The subterrain may be equally valuable for astrobiology. Where surface conditions are particularly hostile, like on Mars, the subsurface may offer the only habitat for extant lifeforms and access to recognizable biosignatures. We have identified numerous unequivocally biogenic macroscopic, microscopic, and chemical/geochemical cave biosignatures. However, to be especially useful for astrobiology, we are looking for suites of characteristics. Ideally, "biosignature suites" should be both macroscopically and microscopically detectable, independently verifiable by nonmorphological means, and as independent as possible of specific details of life chemistries--demanding (and sometimes conflicting) criteria. Working in fragile, legally protected environments, we developed noninvasive and minimal impact techniques for life and biosignature detection/characterization analogous to Planetary Protection Protocols. Our difficult field conditions have shared limitations common to extraterrestrial robotic and human missions. Thus, the cave/subsurface astrobiology model addresses the most important goals from both scientific and operational points of view. We present details of cave biosignature suites involving manganese and iron oxides, calcite, and sulfur minerals. Suites include morphological fossils, mineral-coated filaments, living microbial mats and preserved biofabrics, 13C and 34S values consistent with microbial metabolism, genetic data, unusual elemental abundances and ratios, and crystallographic mineral forms.

To produce definitive and unambiguous results, any life detection experiment must make minimal assumptions about the nature of extraterrestrial life. The only criteria that fits this definition is the ability to reproduce and in the process create a disequilibrium in the chemical and redox environment. The Life Detection Array (LIDA), an instrument proposed for the 2007 NASA Mars Scout Mission, and in the future for the Jovian moons, enables such an experiment. LIDA responds to minute biogenic chemical and physical changes in two identical 'growth' chambers. The sensitivity is provided by two differentially monitored electrochemical sensor arrays. Growth in one of the chambers alters the chemistry and ionic properties and results in a signal. This life detection system makes minimal assumptions; that after addition of water the microorganism replicates and in the process will produce small changes in its immediate surroundings by consuming, metabolizing, and excreting a number of molecules and/or ionic species. The experiment begins by placing an homogenized split-sample of soil or water into each chamber, adding water if soil, sterilizing via high temperature, and equilibrating. In the absence of any microorganism in either chamber, no signal will be detected. The inoculation of one chamber with even a few microorganisms which reproduce, will create a sufficient disequilibrium in the system (compared to the control) to be detectable. Replication of the experiment and positive results would lead to a definitive conclusion of biologically induced changes. The split sample and the nanogram inoculation eliminates chemistry as a causal agent.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The search for sp 2 -bonded carbonaceous material is one of the major life detection strategies of the astrobiological exploration programmes of National Aeronautics and Space Administration and European Space Agency (ESA). The ESA ExoMars rover scheduled for launch in 2018 will include a Raman spectrometer with the goal of detecting sp 2 -bonded carbonaceous material as potential evidence of ancient life. However, sp 2 -bonded carbonaceous material will yield the same Raman spectra of well-developed G and D bands whether they are synthesized biologically or non-biologically. Therefore, the origin and source of sp 2 -bonded carbonaceous material cannot be elucidated by Raman spectroscopy alone. Here, we report the combined approach of Raman spectroscopy and gas chromatography–mass spectrometry biomarker analysis to Precambrian sedimentary rocks, which taken together, provides a promising new methodology for readily detecting and rapidly screening samples for immature organic material amenable to successful biomarker analysis.

Yen et al . ([1][1]) propose that O2 – ions putatively formed in the soil of Mars, not microorganisms, represent “the most straightforward explanation” of my 1976 Viking labeled release (LR) life detection results. Data from radioactive organic nutrients added to martian soil ([2][2]), however