Experimental concepts of life detection for planetary exploration
Life detection for unmanned planetary exploration from extraterrestrial sample involving growth, gas changes and carbon dioxide fixation
Berdahl, B. J.↗
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Organic contamination problems in the Viking molecular analysis experiment
A principal problem in interpreting the results of an organic analysis of an extraterrestrial sample is that of distinguishing contaminating material from indigenous material when unknown types and amounts of contaminants make their way into the sample being analyzed. An approach to control of sample integrity in the Viking molecular analysis experiment has been devised which it is believed, will eliminate such problems. Basically this involves (1) placing an upper limit on the amount of terrestrial contamination that can be tolerated and still allow scientifically meaningful analysis, (2) identifying the potential sources of contamination and analyzing their relative significance, (3) establishing methods to control these sources, and (4) obtaining complete information on the chemical composition of potential contaminants. Previous experience in the Apollo mission has been of great value in developing the Viking program, perhaps the most important carryover being the recognition of the importance of establishing a comprehensive contamination control program in the early stages of mission planning and hardware design.
Flory, D. A.↗
A proposed new policy for planetary protection
A critical review of the present policy was conducted with emphasis on its application to future planetary exploration. The probable impact of recent data on the implementation of the present policy was also assessed. The existing policy and its implementation were found to: be excessive for certain missions (e.g., Voyager), neglect the contamination hazard posed by the bulk constituent organics of spacecraft, be ambiguous for certain missions (e.g., Pioneer Venus), and treat all extraterrestrial sample return missions alike. The major features of the proposed policy are planet/mission combinations, a qualitative top level statement, and implementation by exception rather than rule. The concept of planet/mission categories permits the imposition of requirements according to both biological interest in the target planet and the relative contamination hazard of the mission type.
Barengoltz, J. B.↗
Orbiting Quarantine Facility. The Antaeus report, summary
Requirements for handling extraterrestrial samples in an orbiting quarantine facility are examined. The major concepts and findings of the study are outlined. One approach that could be taken for receiving, containing, and analyzing samples returned from the surface of Mars in a mission analogous to the lunar return missions of the late 1960s and early 1970s is described. It constructs a general mission scenario and presents an overall systems design, including an approach to cost assessment. Particular attention is paid to the design of system hardware components and to the elaboration of an experimental protocol.
Source record↗
Noble gases in planetary atmospheres - Implications for the origin and evolution of atmospheres
The radiogenic and primordial noble gas contents of the Venus, earth, and Mars atmospheres are compared with one another and with the noble gas content of other extraterrestrial samples, particularly meteorites. Key trends in the primordial noble gas content of terrestrial planetary atmospheres are shown to include: (1) a several-orders-of-magnitude decrease in Ne-20 and Ar-36 from Venus to earth to Mars; (2) a nearly constant Ne-20/Ar-36 ratio, which is comparable to that found in the more primitive carbonaceous chondrites and which is two orders of magnitude smaller than the solar ratio; (3) a sizable fractionation of Ar, Kr, and Xe from their solar ratios, though the degree of fractionation (especially for Ar-36/Xe-132) appears to decrease systematically from carbonaceous chondrites to Mars to earth to Venus; and (4) large differences in Ne and Xe isotopic ratios among earth, meteorites, and the sun. It is suggested that the grain-accretion hypothesis can explain all four trends, though the assumptions needed to achieve this agreement are far from proven.
Pollack, J. B.↗
Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution
The Lu-176-Hf-176 isotope method and its applications in earth sciences are discussed with regard to planetary-evolution studies. From new data on basalts from oceanic islands, Hf-176/Hf-177 and Nd-143/Nd-144 are found to display a single linear isotopic variation in the suboceanic mantle, whereas considerable divergences occur in Hf-176/Hf-177-Sr-87/Sr-86 and Nd-143/Nd-144-Sr87/Sr-86 diagrams. With the acquisition of further Hf-Sr-Nd isotopic data, these discordant Sr-87/Sr-86 relationships may allow a distinction between processes such as mantle metasomatism, influence of sea-water altered material in the magma source, or recycling of sediments into the mantle. The best quality Hf isotope data are obtained from granitoid or zircons, and are most suitable for studying ancient terrestrial Hf isotopic variations. Lu-Hf is shown to be a viable method for dating ancient terrestrial and extraterrestrial samples, but is unlikely to find wide application in pure chronological studies because it offers little advantage over existing methods.
Patchett, P. J.↗
Synthesis and analysis in studies of chemical evolution
Studies of the various processes that may have given rise to life on the Earth have demonstrated the appropriateness of an approach that makes use of analysis and synthesis. Analysis of extraterrestrial samples in the form of meteorites has demonstrated the presence of several precursors of biomolecules, most notably a full suite of nucleic acid bases and nucleotides of biological significance. These species were determined after exhaustive extraction of the sample and subsequent analysis using HPLC, GC, MS, and GC-MS. Procedural blanks indicate that these molecules are likely not the result of contamination during the extraction and analysis process. Similar species were found as products of spark discharge experiments in atmospheres thought to mimic primitive Earth conditions. These results indicate that the basic chemistry underlying these syntheses is common, and that life may not be unique to the Earth. Studies underway in the laboratory make use of proton nuclear magnetic resonance spectroscopy as a probe to assess associations between selected amino acids and any of several nucleotides comprising their genetic code and genetic anticode sequences. These studies demonstrate a clear selectivity by the anticode sequences, thus confirming the hydrophobicity studies performed by Lacey et al. These studies further support the contention that life is likely a natural result of the physics and chemistry of the universe.
Ponnamperuma, C.↗
Use of mercuric iodide X-ray detectors with alpha backscattering spectrometers for space applications
The authors present X-ray fluorescence (XRF) spectra of different extraterrestrial samples taken with a mercuric iodide (HgI2) spectrometer inserted into an alpha backscattering instrument identical to that used in the Soviet Phobos mission. The results obtained with the HgI2 ambient temperature detector are compared with those obtained using an Si(Li) cryogenically cooled detector. Efforts to design an optimized instrument for space application are also described. The results presented indicate that the energy resolution and sensitivity of HgI2 detectors are adequate to meet the performance needs of a number of proposed space applications, particularly those in which cooled silicon X-ray detectors are impractical or even not usable, such as for the target science programs on geoscience opportunities for lunar surface, Mars surface, and other comet and planetary missions being planned by NASA and ESA.
Iwanczyk, J. S.↗
Studies of Life on Earth are Important for Mars Exploration
The search for evidence of the early martian environment and a martian biosphere is benefitted by diverse studies of life on Earth. Most fundamentally, origin-of-life research highlights the challenge in formulating a rigorous definition of life. Because such definitions typically list several of life's most basic properties, they also help to define those observable features that distinguish life and thus might be sought through telescopes, spacecraft, and analyses of extraterrestrial samples. Studies of prebiotic chemistry also help by defining the range of environments and processes that sustain prebiotic organic synthesis. These studies might indicate if and where prebiotic processes occur today on Earth and elsewhere. Such studies should also help to identify which localities are good candidates for the origin of life. A better understanding of the most fundamental principles by which molecules are assembled into living systems will help us to appreciate possible alternatives to the path followed by life on Earth. These perspectives will sharpen our ability to recognize exotic life and/or those environments that can sustain it.
DesMarais, D. J.↗
Interpretation of Fe-XANES Pre-Edge Spectra: Predictions Based on Co and Fe Optical Spectra
Microanalysis of Fe-3+/Total(Fe) in extraterrestrial samples is important due to sample size constraints of sample return missions. We compare Fe XANES spectra with Co optical spectra that predict valence electron levels based on 'Z1' model. Additional information is contained in the original extended abstract.
Dyar, M. D.↗
Fiducial Marks for Location of Particles in Aerogel
If an extraterrestrial sample is captured in aerogel as a collection of particles, it is important to be able to consistently locate individual grains when changing instruments or laboratories. We report on a feasibility study for applying fiducial marks to aerogel nondestructively so that the marks can eventually be used with optical, X-ray or other (manual or automated) location techniques.
Jurewicz, A. J. G.↗
Forward Contamination of the Moon and Mars: Implications for Future Life Detection Missions
NASA and ESA have outlined new visions for solar system exploration that will include a series of lunar robotic missions to prepare for, and support a human return to the Moon, and future human exploration of Mars and other destinations. One of the guiding principles for exploration is to pursue compelling scientific questions about the origin and evolution of life. The search for life on objects such as Mars will require that all spacecraft and instrumentation be sufficiently cleaned and sterilized prior to launch to ensure that the scientific integrity of extraterrestrial samples is not jeopardized by terrestrial organic contamination. Under COSPAR's current planetary protection policy for the Moon, no sterilization procedures are required for outbound lunar spacecraft. Nonetheless, future in situ investigations of a variety of locations on the Moon by highly sensitive instruments designed to search for biologically derived organic compounds would help assess the contamination of the Moon by lunar spacecraft. These studies could also provide valuable "ground truth" data for Mars sample return missions and help define planetary protection requirements for future Mars bound spacecraft carrying life detection experiments. In addition, studies of the impact of terrestrial contamination of the lunar surface by the Apollo astronauts could provide valuable data to help refine future Mars surface exploration plans for a human mission to Mars.
Glavin, Daniel P.↗
Chemical Mapping of Proterozoic Organic Matter at Sub-Micron Spatial Resolution
We have used a NanoSIMS ion microprobe to map sub-micron-scale distributions of carbon, nitrogen, sulfur, silicon, and oxygen in organic microfossils and laminae from the approximately 0.85 Ga Bitter Springs Formation of Australia. The data provide clues about the original chemistry of the microfossils, the silicification process, and biosignatures of specific microorganisms and microbial communities. Chemical maps of fossil unicells and filaments reveal distinct wall-and sheath-like structures enriched in C, N and S, consistent with their accepted biological origin. Surprisingly, organic laminae, previously considered to be amorphous, also exhibit filamentous and apparently compressed spheroidal structures defined by strong enrichments in C, N and S. By analogy to data from the well-preserved microfossils, these structures are interpreted as being of biological origin, most likely representing densely packed remnants of microbial mats. Because the preponderance of organic matter in Precambrian sediments is similarly "amorphous," our findings open a large body of generally neglected material to in situ structural, chemical, and isotopic study. Our results also offer new criteria for assessing biogenicity of problematic kerogenous materials and thus can be applied to assessments of poorly preserved or fragmentary organic residues in early Archean sediments and any that might occur in meteorites or other extraterrestrial samples.
Oehler, Dorothy Z.↗
A Review of the Approach of NASA Projects to Planetary Protection Compliance
NASA planetary protection, formerly planetary quarantine, is a set of regulations for extraterrestrial space missions which addresses applicable COSPAR resolutions, and ultimately derives from a 1967 United Nations treaty (the "Moon treaty"). The purpose of the NASA regulations is set forth in a basic policy, NPD 8020.7E (Ref. 1). The purposes are: to protect extraterrestrial objects from terrestrial biological contamination that may interfere with the search for extant life or its remnants or its precursors; and to protect the Earth from the possible hazards of an extraterrestrial sample return.
planetary protections↗
Preliminary Examination of the Interstellar Collector of Stardust
The findings of the Stardust spacecraft mission returned to earth in January 2006 are discussed. The spacecraft returned two unprecedented and independent extraterrestrial samples: the first sample of a comet and the first samples of contemporary interstellar dust. An important lesson from the cometary Preliminary Examination (PE) was that the Stardust cometary samples in aerogel presented a technical challenge. Captured particles often separate into multiple fragments, intimately mix with aerogel and are typically buried hundreds of microns to millimeters deep in the aerogel collectors. The interstellar dust samples are likely much more challenging since they are expected to be orders of magnitudes smaller in mass, and their fluence is two orders of magnitude smaller than that of the cometary particles. The goal of the Stardust Interstellar Preliminary Examination (ISPE) is to answer several broad questions, including: which features in the interstellar collector aerogel were generated by hypervelocity impact and how much morphological and trajectory information may be gained?; how well resolved are the trajectories of probable interstellar particles from those of interplanetary origin?; and, by comparison to impacts by known particle dimensions in laboratory experiments, what was the mass distribution of the impacting particles? To answer these questions, and others, non-destructive, sequential, non-invasive analyses of interstellar dust candidates extracted from the Stardust interstellar tray will be performed. The total duration of the ISPE will be three years and will differ from the Stardust cometary PE in that data acquisition for the initial characterization stage will be prolonged and will continue simultaneously and parallel with data publications and release of the first samples for further investigation.
Westphal, A. J.↗
'Nano' Morphology and Element Signatures of Early Life on Earth: A New Tool for Assessing Biogenicity
The relatively young technology of NanoSIMS is unlocking an exciting new level of information from organic matter in ancient sediments. We are using this technique to characterize Proterozoic organic material that is clearly biogenic as a guide for interpreting controversial organic structures in either terrestrial or extraterrestrial samples. NanoSIMS is secondary ion mass spectrometry for trace element and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS element maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity of Precambrian structures. The ability of NanoSIMS to map simultaneously the distribution of organic elements with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on Earth. The current study corroborates the work of Robert et al. and builds on their study by using NanoSIMS to map C, N (as CN), S, Si and O of both excellently preserved microfossils and less well preserved, non-descript organics in Proterozoic chert from the ca. 0.8 Ga Bitter Springs Formation of Australia.
Oehler, D. Z.↗
The Stuff of Other Worlds
Extraterrestrial material eternally rains down on Earth. Meteorites flare in the night sky. Cosmic rays plow into Earth's atmosphere, creating invisible bursts of secondary particles. These processes began when the Earth formed in the primordial solar system and have continued ever since, indifferent to the exceedingly recent presence of human intelligence. For us to seek out stuff of other worlds, in contrast, takes a great deal of determined ingenuity. First we have to send a spacecraft somewhere else in the solar system. Indigenous material has to be collected and then brought back to Earth without exposure to conditions that might significantly alter it. The material must undergo meaningful scientific analysis. Most important, part of the material is preserved intact for future investigations. Beginning with bringing back Moon rocks, and now moving onward in the form of new missions to capture the hot thin solar wind and cold thin atmosphere of comets, extraterrestrial sample return takes place on the cutting edge of scientific technology. Sample return is also the fulcrum of an energetic debate about how to do planetary science missions. Scientists and engineers are debating whether to rely on remote sensing and in situ analysis, or to plan missions to undertake sample return. The latter is definitely more expensive on a per mission basis, and is usually technologically more challenging. But for an initially high investment of money and technology, bringing the stuff of other worlds back to Earth yields an incomparable return in scientific results.
Stansbery, EIleen K.↗
GeoLab in NASA's Pressurized Excursion Module: First Results from the 2010 Field Trials
Before humans explore other planets, NASA must develop advanced techniques for collection, preservation and return of unique extraterrestrial samples. To help evaluate hardware requirements and operational concepts for future sample-return missions, we designed and built GeoLab our first generation lab for geological samples into NASA s Habitat Demonstration Unit in the Pressurized Excursion Module (HDU1-PEM). The center of GeoLab is a glovebox for the examination of samples in a shirt-sleeve environment. As part of a deployable habitat, GeoLab can participate in NASA s analog missions that simulate planetary exploration activities and support the testing of relevant technologies for collecting and handling geological samples. Over time, these tests will evaluate sample handling environments (field and lab), sampling tools and analytical instruments, and different scenarios involving both robotic and human procedures. The GeoLab design supports evolving tests and configurations. The glovebox is mounted on the habitat bulkhead, with three sample pass-though chambers that allow for direct sample transfer into the glovebox from the outside. The glovebox design and construction (low-particle shedding, minimally off-gassing materials) provides a clean environment to reduce sample contamination; in the future, we will integrate a positive pressure, enriched nitrogen atmosphere. The glovebox is equipped with configurable instrument ports. The 2010 test included a mass balance, a stereomicroscope with a HD camera for detailed imaging of samples, and a handheld XRF analyzer for preliminary geochemical characterization of samples. Network cameras provided context imagery and sample handling activities. We present early results from the initial field trial of GeoLab during the 2010 Desert Research and Technology Studies (D-RATS) planetary analog test near Flagstaff AZ. The 2010 D-RATS mission involved two rovers, the habitat with GeoLab, four crew members, and a team of scientists and flight controllers. The crewed rovers conducted geological traverses and collected samples on the planetary surface. Selected samples were transferred into GeoLab for detailed examination and initial analysis, providing critical data to the science team for evaluation and prioritization of samples.
Evans, Cynthia A.↗