Sherry L Cady

Doctor Penelope Boston is the new Director of the NASA Astrobiology Institute at NASA Ames Research Center in California (May 2016). From 2002 to 2016, she served as Associate Director of the National Cave and Karst Research Institute (Carlsbad, NM), Professor and Chair of the Earth and Environmental Sciences Department at the New Mexico Institute of Mining and Technology (NMT, Socorro, NM), and Director of the Cave and Karst Studies Program at NMT. Personal research areas include geomicrobiology and astrobiology in extreme environments (especially caves and mines, hot and cold deserts, high latitudes and altitudes); geological processes creating caves on other planets and moons; human life-support issues in space and planetary environments; and use of robotics and other technologies to assist exploration and advance science in extreme Earth and extraterrestrial environments. Boston is author of over 160 technical and popular publications and editor of four volumes. Her work has been featured in *200 print and broadcast media outlets. As a child of a theatrical family, she first went on the stage at the age of 3 and apparently hasn’t come off since.. She has served on the NRC Space Studies Board, the NASA Advisory Council Planetary Protection Subcommittee, and the External Council of the NASA Innovative Advanced Concepts. Boston is recipient of the 2010 Lifetime Achievement in Science Award from the National Speleological Society, a Fellow of the NASA Institute for Advanced Concepts (since 2000), a recent Distinguished Visiting Lecturer for Phi Beta Kappa (2013–2014), and recipient of the Caving Legend Award (!) from Ft. Stanton Cave Study Project/BLM. As a graduate student in the 1980s, she cofounded the Case for Mars series of conferences and activities devoted to the human exploration of Mars. Boston holds a PhD from the University of Colorado, Boulder, in Microbiology and Atmospheric Chemistry, earned on an Advanced Studies Program Fellowship at the National Center for Atmospheric Research (Boulder, CO). She was a National Research Council/NASA Postdoctoral Fellow at NASA Langley Research Center (Hampton, VA, 1986 and 1987).

Astrobiology brings together scientific disciplines focused on deciphering the origin of life, its nature, evolution, and distribution in the universe. Exceptionally rapid progress in our understanding has been made over the past four decades, including new insights into how life could have emerged on Earth, the revelation that life can thrive in the most hostile terrestrial environments, evidence of the presence of liquid water throughout the universe, a controversial discovery of past life in a Martian meteorite that reinvigorated the search for life on Mars, and the discovery of Earth-like planets orbiting stars other than our Sun in the Milky Way. Although Earth is the only planet known to host life in our Solar System, continued advances in the field of astrobiology stimulate the search for life and its origin beyond our planet.

Hydrothermal systems have been cited as important targets in the search for evidence of an ancient biosphere on Mars (1,2). Indeed, such environments appear to have been widespread on Mars earlier in its history (3), while subsurface hydrothermal systems may have provided clement environments for life throughout the subsequent history of planet. Comparative studies of modern and ancient hydrothermal systems on Earth have the potential to provide important constraints on longterm evolutionary trends in hydrothermal ecosystems (4). And the results of such studies also assist in refining strategies to explore Mars for a fossil record of ancient hydrothermal life. To create a comparative framework for interpreting the fossil record of ancient hydrothermal deposits on the Earth, and possibly Mars, we have carried out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of active hydrothermal environments in Yellowstone National Park. One goal of the research is ...

N.A. Cabrol, W.H. Diamond, N. Altaf, J. Bishop, S.L. Cady, L. Fenton, N. Hinman, S. Jain, A. Lowndes, G. Mackintosh, J. Moersch, K. McGivern, N. Noffke, M. Phillips, B. Poduval, K. Warren-Rhodes, and J. Parr. 1. SETI Institute; 2. IBM Watson & Cloud Platform; 3. Pacific Northwest National Laboratory; 4. University of Montana; 5. Intel Corporation; 6.NVIDIA; 7. University of Tennessee, Knoxville; 8. KX Solutions; 9. Old Dominion University; 10. Space Science Institute. Primary contact; 11. FDL Director: ncabrol@seti.org

Subsurface habitats on Earth host an extensive extant biosphere and likely provided one of Earth’s earliest microbial habitats. Although the site of life’s emergence continues to be debated, evidence of early life provides insights into its early evolution and metabolic affinity. Here, we present the discovery of exceptionally well-preserved, ~3.42-billion-year-old putative filamentous microfossils that inhabited a paleo-subseafloor hydrothermal vein system of the Barberton greenstone belt in South Africa. The filaments colonized the walls of conduits created by low-temperature hydrothermal fluid. Combined with their morphological and chemical characteristics as investigated over a range of scales, they can be considered the oldest methanogens and/or methanotrophs that thrived in an ultramafic volcanic substrate.

Abstract For nearly 40 years, hydrothermal deposits have been recognized as potential paleobiological repositories for astrobiological exploration of Mars. Here, we summarize the motivation for this astrobiological search strategy as it pertains to our current understanding of silica-depositing hot spring ecosystems and terrestrial siliceous hot spring deposits. We also discuss the rover and orbital observations of recently discovered hydrothermal opaline silica deposits on Mars—interpreted as evidence of hot spring activity. The opaline silica digitate sinters near Columbia Hills represent the strongest evidence to date for potential fossilized biosignatures on Mars. The high habitability and preservation potentials of hot spring deposits on Earth, along with their ability to reveal insight into the metabolic evolution of life, strengthen the rationale for targeting siliceous hot spring deposits as high-priority astrobiology sites for future Mars missions.

... Microbial biosignatures provide trace evidence of microbial life, past and present, and can be divided into three categories (Cady, 2001). ... 0.3 (Table 1). The occurrence of natural and artificial siliceous ferrihydrite is well documented in the literature (eg, Carlson and Schwertmann ...

Banded Iron Formations (BIFs) are widespread Precambrian sedimentary deposits, the least metamorphosed of which often contain hematite and magnetite among the major oxide mineral species. Hypotheses developed to explain the origin of BIFs differ with regard to the mechanisms by which Fe2+ would have been oxidized to mixed ferric (Fe3+) mineral assemblages. The classical scenario is that oxidation occurred biotically,

To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

RESUME Thermophilic microbial communities that thrive in the geysers and hot springs of Yellowstone National Park represent analogs of some of Earth's earliest inhabitants. We report here on the mineralization of microorganisms observed in alkaline silica-depositing hot springs located in Yellowstone National Park. Analytical scanning electron microscopy of microbial streamers revealed that fossilization results from the aggregation of opal-A colloids. Patterns of deposition strongly suggest at least two distinct modes of formation for the colloids: homogeneous precipitation from supersaturated hydrothermal fluids that build up inside cells, and heterogeneous precipitation and flocculation from supersaturated solutions in the sheaths of the bacterium and on microbial cell surfaces.

Microcrystalline opal varieties form as intermediary precipitates during the diagenetic transformation of biogenically precipitated non-crystalline opal (opal-A) to microquartz. With regard to the Monterey Formation of California, X-ray powder diffraction studies have shown that a decrease in the primary d-spacing of opal-CT toward that of cristobalite occurs with increasing diagenesis. The initial timing of opal-CT/quartz formation and the value of the primary opal-CT d-spacing, are influenced by the sediment. lithology. Transmission electron microscopy methods (CTEM/HRTEM) were used to investigate the structure of the diagenetic phases and establish transformation mechanisms between the varieties of microcrystalline opals in charts and porcelanites from the Monterey Formation. HRTEM images revealed that the most common fibrous varieties of microcrystalline opals contain varying amounts of structural disorder. Finite lamellar units of cristobalite-and tridymite-type. layer sequence...

Banded Iron Formations (BIFs) are widespread Precambrian sedimentary deposits that accumulated in deep ocean basins or shallow platformal areas with inputs of reduced iron (Fe(II)) and silica from deep ocean hydrothermal activity. There is debate as to whether abiotic or biotic mechanisms were responsible for the oxidation of aqueous Fe(II) and the subsequent accumulation of ferric iron (Fe(III)) mineral assemblages in BIFs. Biotic Fe(II) oxidation could have occurred indirectly as a result of the photosynthetic production of oxygen by cyanobacteria, or could have been directly mediated by anoxygenic phototrophs or chemolithotrophs. The anoxygenic use of Fe(II) as an electron donor for photosynthesis has also been hypothesized in cyanobacteria, representing another biotic mechanism by which Fe(II) could be oxidized in BIFs. This type of photoferrotrophic metabolism may also represent a key step in the evolution of oxygenic photosynthesis. Members of our group have speculated that an...

The emerging anoxic source waters at Chocolate Pots hot springs in Yellowstone National Park contain 2.6 to 11.2 mg/L Fe(II) and are 51-54° C and pH 5.5-6.0. These waters flow down the accumulating iron deposits and over three major phototrophic mat communities: Synechococcus/Chloroflexus at 51-54° C, Pseudanabaena at 51-54° C, and a narrow Oscillatoria at 36-45° C. We are assessing the contribution of the phototrophs to biosignature formation in this high iron system. These biosignatures can be used to assess the biological contribution to ancient iron deposits on Earth (e.g. Precambrian Banded Iron Formations) and, potentially, to those found on Mars. Most studies to date have focused on chemotrophic iron-oxidizing communities; however, recent research has demonstrated that phototrophs have a significant physiological impact on these iron thermal springs (Pierson et al. 1999, Pierson and Parenteau 2000, and Trouwborst et al., 2003). We completed a survey of the microfossils, biomi...

We have been studying a subaerial terrestrial iron hot spring as an potential analog for hydrothermal systems on Mars. In this multidisciplinary study, we have characterized the aqueous geochemistry, mineralogy, and microbial biosignatures at Chocolate Pots hot springs.

The mission of the United States Culture Collection Network (USCCN;http://usccn.org) is “to facilitate the safe and responsible utilization of microbial resources for research, education, industry, medicine, and agriculture for the betterment of human kind.” Microbial culture collections are a key component of life science research, biotechnology, and emerging global biobased economies. Representatives and users of several microbial culture collections from the United States and Europe gathered at the University of California, Davis, to discuss how collections of microorganisms can better serve users and stakeholders and to showcase existing resources available in public culture collections.

To enhance our ability to extract palaeobiological and palaeoenvironmental information from ancient thermal spring deposits, we have studied the processes responsible for the development and preservation of stromatolites in modern subaerial thermal spring systems in Yellowstone National Park (USA). We investigated specimens collected from silica-depositing thermal springs along the thermal gradient using petrographic techniques and scanning electron microscopy. Although it is known that thermophilic cyanobacteria control the morphogenesis of thermal spring stromatolites below 73 degrees C, we have found that biofilms which contain filamentous thermophiles contribute to the microstructural development of subaerial geyserites that occur along the inner rims of thermal spring pools and geyser effluents. Biofilms intermittently colonize the surfaces of subaerial geyserites and provide a favoured substrate for opaline silica precipitation. We have also found that the preservation of biot...

The biogenicity of ancient morphological microfossil-like objects can be established by linking morphological (e.g. cell remnants and extracellular polymeric matrix) and chemical (e.g. isotopes, biomarkers and biominerals) evidence indicative of microorganisms or microbial activity. We have developed a non-destructive micro-analytical ion beam system capable of measuring with high spatial resolution the stable carbon isotope ratios of thin samples used for

The Geological Society of America Field Guide 15 2009 A tale of two basins: Comparisons and contrasts in the high desert hydrogeology ofSteens Mountain, southeastern Oregon Michael L. Cummings* Sherry L. Cady Robert B. Perkins Department of Geology, Portland State ...