Astrobiological Stoichiometry

Young, Patrick; Desch, S. J.; Anbar, Ariel D.; Barnes, Rory; Hinkel, Natalie R.; Kopparapu, Ravikumar; Madhusudhan, Nikku; Monga, Nikhil; Pagano, Michael; Riner, M. A.; Scannapieco, Evan; Shim, Sang‐Heon; Truitt, Amanda

doi:10.1089/ast.2014.1143

Cited by 29 publications

(23 citation statements)

References 163 publications

(167 reference statements)

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“…If the trace element stoichiometry of life on Earth is but a sort of chemical ‘vestigial characteristic’ of the environment in which it emerged, one might expect lifeforms in extraterrestrial environments to use trace metals for redox metabolism in proportions that also mirror the environment of their emergence. Some extrasolar environments seem to provide an elemental supply radically different from Earth's (Young et al ., ); thus, we do not expect the trace elemental ranges reported in this study to hold for putative life that may have emerged in such exotic planetary settings.…”

Section: Discussionmentioning

confidence: 72%

Ordinary stoichiometry of extraordinary microorganisms

et al. 2015

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All life on Earth seems to be made of the same chemical elements in relatively conserved proportions (stoichiometry). Whether this stoichiometry is conserved in settings that differ radically in physicochemical conditions (extreme environments) from those commonly encountered elsewhere on the planet provides insight into possible stoichiometries for putative life beyond Earth. Here, we report measurements of elemental stoichiometry for extremophile microbes from hot springs of Yellowstone National Park (YNP). Phototrophic and chemotrophic microbes were collected in locations spanning large ranges of temperature (24 °C to boiling), pH (1.6-9.6), redox (0.1-7.2 mg L(-1) dissolved oxygen), and nutrient concentrations (0.01-0.25 mg L(-1) NO2-, 0.7-12.9 mg L(-1) NO3-, 0.01-42 mg L(-1) NH4 (+), 0.003-1.1 mg L(-1) P mostly as phosphate). Despite these extreme conditions, the microbial cells sampled had a major and trace element stoichiometry within the ranges commonly encountered for microbes living in the more moderate environments of lakes and surface oceans. The cells did have somewhat high C:P and N:P ratios that are consistent with phosphorus (P) limitation. Furthermore, chemotrophs and phototrophs had similar compositions with the exception of Mo content, which was enriched in cells derived from chemotrophic sites. Thus, despite the extraordinary physicochemical and biological diversity of YNP environments, life in these settings, in a stoichiometric sense, remains much the same as we know it elsewhere.

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Section: Discussionmentioning

confidence: 72%

Ordinary stoichiometry of extraordinary microorganisms

et al. 2015

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“…Though typically constituting only ∼1.5% of a star's mass, the elements with Z > 2 play an essential role in the origins and evolution of terrestrial planets. Young et al (2014) summarized the findings of several observational astronomy groups engaged in quantitative spectroscopic measurements of stars to determine element abundances and ratios-an effort known as "stellar stoichiometry." They concluded that stellar concentrations and relative amounts of such key elements as Al, C, Ca, Mg, Na, O, and Si may differ by factors of at least two compared to the Sun.…”

Section: Stellar Stoichiometrymentioning

confidence: 99%

Mineral Ecology: Chance and Necessity in the Mineral Diversity of Terrestrial Planets

Hazen¹,

Grew²,

Downs³

et al. 2015

Can Mineral

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Four factors contribute to the roles played by chance and necessity in determining mineral distribution and diversity at or near the surfaces of terrestrial planets: (1) crystal chemical characteristics; (2) mineral stability ranges; (3) the probability of occurrence for rare minerals; and (4) stellar and planetary stoichiometries in extrasolar systems.The most abundant elements generally have the largest numbers of mineral species, as modeled by relationships for Earth's upper continental crust (E) and the Moon (M), respectively: LogðN E Þ ¼ 0:22 LogðC E Þ þ 1:70 ðR 2 ¼ 0:34Þð4861 minerals; 72 elementsÞ LogðN M Þ ¼ 0:19 LogðC M Þ þ 0:23 ðR 2 ¼ 0mineral species await discovery or could have occurred at some point in Earth's history, only to be subsequently lost by burial, erosion, or subduction-i.e., much of Earth's mineral diversity associated with rare species results from stochastic processes.Measurements of stellar stoichiometry reveal that stars can differ significantly from the Sun in relative abundances of rock-forming elements, which implies that bulk compositions of some extrasolar Earth-like planets likely differ significantly from those of Earth, particularly if the fractionation processes in evolving stellar nebulas and planetary differentiation are factored in. Comparison of Earth's upper continental crust and the Moon shows that differences in element ratios are reflected in ratios of mineral species containing these elements.In summary, although deterministic factors control the distribution of the most common rock-forming minerals in Earth's upper continental crust and on the Moon, stochastic processes play a significant role in the diversity of less common minerals. Were Earth's history to be replayed, and thousands of mineral species discovered and characterized anew, it is probable that many of those minerals would differ from species known today.

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“…McKinnon et al (2008) cautioned that any direct extrapolation from present-day comets to volatiles accreted by KBOs overlooks evolutionary effects on cometary volatile-to-water ratios (e.g., Shock and McKinnon, 1993). Interstellar cloud abundances and direct observation of inner extrasolar disk compositions are also biased, because the bulk compositions of extrasolar systems may be widely different from that of the solar system (Young et al, 2014 (Mumma and Charnley, 2011) that are of same order of magnitude as those observed in extrasolar disks (Maret et al, 2006;Carr and Najita, 2008), although the CO 2 abundances differ significantly. The general consistency between these values provides guidance to estimate primordial volatile abundances in the solar system.…”

Section: Volatile Inventory Of Kbosmentioning

confidence: 99%

Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

Neveu

Desch

Shock

et al. 2015

Icarus

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Explosive extrusion of cold material from the interior of icy bodies, or cryovolcanism, has been observed on Enceladus and, perhaps, Europa, Triton, and Ceres. It may explain the observed evidence for a young surface on Charon (Pluto's surface is masked by frosts). Here, we evaluate prerequisites for cryovolcanism on dwarf planet-class Kuiper belt objects (KBOs). We first review the likely spatial and temporal extent of subsurface liquid, proposed mechanisms to overcome the negative buoyancy of liquid water in ice, and the volatile inventory of KBOs. We then present a new geochemical equilibrium model for volatile exsolution and its ability to drive upward crack propagation. This novel approach bridges geophysics and geochemistry, and extends geochemical modeling to the seldom-explored realm of liquid water at subzero temperatures. We show that carbon monoxide (CO) is a key volatile for gas-driven fluid ascent; whereas CO 2 and sulfur gases only play a minor role. N 2 , CH 4 , and H 2 exsolution may also drive explosive cryovolcanism if hydrothermal activity produces these species in large amounts (a few percent with respect to water). Another important control on crack propagation is the internal structure: a hydrated core makes explosive cryovolcanism easier, but an undifferentiated crust does not. We briefly discuss other controls on ascent such as fluid freezing on crack walls, and outline theoretical advances necessary to better understand cryovolcanic processes. Finally, we make testable predictions for the 2015 New Horizons flyby of the Pluto-Charon system.

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Astrobiological Stoichiometry

Cited by 29 publications

References 163 publications

Ordinary stoichiometry of extraordinary microorganisms

Ordinary stoichiometry of extraordinary microorganisms

Mineral Ecology: Chance and Necessity in the Mineral Diversity of Terrestrial Planets

Prerequisites for explosive cryovolcanism on dwarf planet-class Kuiper belt objects

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