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Astrobiology

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https://www.readbyqxmd.com/read/29345987/habitable-worlds-delivering-on-the-promises-of-online-education
#1
Lev B Horodyskyj, Chris Mead, Zack Belinson, Sanlyn Buxner, Steven Semken, Ariel D Anbar
Critical thinking and scientific reasoning are central to higher education in the United States, but many courses (in-person and online) teach students information about science much more than they teach the actual process of science and its associated knowledge and skills. In the online arena specifically, the tools available for course construction exacerbate this problem by making it difficult to build the types of active learning activities that research shows to be the most effective. Here, we present a report on Habitable Worlds, offered by Arizona State University for 12 semesters over the past 6 years...
January 2018: Astrobiology
https://www.readbyqxmd.com/read/29345986/vital-signs-seismology-of-icy-ocean-worlds
#2
Steven D Vance, Sharon Kedar, Mark P Panning, Simon C Stähler, Bruce G Bills, Ralph D Lorenz, Hsin-Hua Huang, W T Pike, Julie C Castillo, Philippe Lognonné, Victor C Tsai, Alyssa R Rhoden
Ice-covered ocean worlds possess diverse energy sources and associated mechanisms that are capable of driving significant seismic activity, but to date no measurements of their seismic activity have been obtained. Such investigations could reveal the transport properties and radial structures, with possibilities for locating and characterizing trapped liquids that may host life and yielding critical constraints on redox fluxes and thus on habitability. Modeling efforts have examined seismic sources from tectonic fracturing and impacts...
January 2018: Astrobiology
https://www.readbyqxmd.com/read/29321597/microbial-habitability-of-europa-sustained-by-radioactive-sources
#3
Thiago Altair, Marcio G B de Avellar, Fabio Rodrigues, Douglas Galante
There is an increasing interest in the icy moons of the Solar System due to their potential habitability and as targets for future exploratory missions, which include astrobiological goals. Several studies have reported new results describing the details of these moons' geological settings; however, there is still a lack of information regarding the deep subsurface environment of the moons. The purpose of this article is to evaluate the microbial habitability of Europa constrained by terrestrial analogue environments and sustained by radioactive energy provided by natural unstable isotopes...
January 10, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29319335/astrovirology-viruses-at-large-in-the-universe
#4
Aaron J Berliner, Tomohiro Mochizuki, Kenneth M Stedman
Viruses are the most abundant biological entities on modern Earth. They are highly diverse both in structure and genomic sequence, play critical roles in evolution, strongly influence terran biogeochemistry, and are believed to have played important roles in the origin and evolution of life. However, there is yet very little focus on viruses in astrobiology. Viruses arguably have coexisted with cellular life-forms since the earliest stages of life, may have been directly involved therein, and have profoundly influenced cellular evolution...
January 10, 2018: Astrobiology
https://www.readbyqxmd.com/read/29314901/secondary-electrons-as-an-energy-source-for-life
#5
Kamil B Stelmach, Marc Neveu, Trista J Vick-Majors, Rebecca L Mickol, Luoth Chou, Kevin D Webster, Matt Tilley, Federica Zacchei, Cristina Escudero, Claudio L Flores Martinez, Amanda Labrado, Enrique J G Fernández
Life on Earth is found in a wide range of environments as long as the basic requirements of a liquid solvent, a nutrient source, and free energy are met. Previous hypotheses have speculated how extraterrestrial microbial life may function, among them that particle radiation might power living cells indirectly through radiolytic products. On Earth, so-called electrophilic organisms can harness electron flow from an extracellular cathode to build biomolecules. Here, we describe two hypothetical mechanisms, termed "direct electrophy" and "indirect electrophy" or "fluorosynthesis," by which organisms could harness extracellular free electrons to synthesize organic matter, thus expanding the ensemble of potential habitats in which extraterrestrial organisms might be found in the Solar System and beyond...
January 9, 2018: Astrobiology
https://www.readbyqxmd.com/read/29310228/development-of-liquid-chromatography-high-resolution-mass-spectrometry-strategies-for-the-screening-of-complex-organic-matter-application-to-astrophysical-simulated-materials
#6
Balkis Eddhif, Audrey Allavena, Sylvie Liu, Thomas Ribette, Ninette Abou Mrad, Thierry Chiavassa, Louis Le Sergeant d'Hendecourt, Robert Sternberg, Gregoire Danger, Claude Geffroy-Rodier, Pauline Poinot
The present work aims at developing two LC-HRMS setups for the screening of organic matter in astrophysical samples. Their analytical development has been demonstrated on a 100-µg residue coming from the photo-thermo chemical processing of a cometary ice analog produced in laboratory. The first 1D-LC-HRMS setup combines a serially coupled columns configuration with HRMS detection. It has allowed to discriminate among different chemical families (amino acids, sugars, nucleobases and oligopeptides) in only one chromatographic run without neither a priori acid hydrolysis nor chemical derivatisation...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29298093/the-search-for-hesperian-organic-matter-on-mars-pyrolysis-studies-of-sediments-rich-in-sulfur-and-iron
#7
James M T Lewis, Jens Najorka, Jonathan S Watson, Mark A Sephton
Jarosite on Mars is of significant geological and astrobiological interest, as it forms in acidic aqueous conditions that are potentially habitable for acidophilic organisms. Jarosite can provide environmental context and may host organic matter. The most common extraction technique used to search for organic compounds on the surface of Mars is pyrolysis. However, thermal decomposition of jarosite releases oxygen into pyrolysis ovens, which degrades organic signals. Jarosite has a close association with the iron oxyhydroxide goethite in many depositional/diagenetic environments...
January 3, 2018: Astrobiology
https://www.readbyqxmd.com/read/29297697/the-impact-of-the-temporal-distribution-of-communicating-civilizations-on-their-detectability
#8
Amedeo Balbi
We used a statistical model to investigate the detectability (defined by the requirement that causal contact has been initiated with us) of communicating civilizations within a volume of the Universe surrounding our location. If the civilizations are located in our galaxy, the detectability requirement imposes a strict constraint on their epoch of appearance and their communicating life span. This, in turn, implies that our ability to gather empirical evidence of the fraction of civilizations within range of detection strongly depends on the specific features of their temporal distribution...
January 3, 2018: Astrobiology
https://www.readbyqxmd.com/read/29291590/patterns-of-cation-binding-to-the-aromatic-amino-acid-r-groups-in-trp-tyr-and-phe
#9
Shelby L Scherer, Amanda L Stewart, Ryan C Fortenberry
Previous joint experimental and theoretical work demonstrates that typically soluble peptides will be rendered insoluble in the presence of saturated sodium ions in aqueous solution due to disruption of cation-π interactions between Trp and Lys. The present work utilizes quantum chemical methods including density functional theory, symmetry-adapted perturbation theory, and even coupled cluster theory to determine the strengths of cation-π interactions for the aromatic R groups of Trp, Tyr, and Phe (approximated as skatole, methyl phenol, and toluene) with both alkali and alkaline-Earth atomic cations and electron-accepting R groups from Lys, Arg, and His approximated as methyl ammonium, guanidinium, and imidazolium cations...
December 27, 2017: Computational Biology and Chemistry
https://www.readbyqxmd.com/read/29283671/photobiological-effects-at-earth-s-surface-following-a-50%C3%A2-pc-supernova
#10
Brian C Thomas
We investigated the potential biological impacts at Earth's surface of stratospheric O3 depletion caused by nearby supernovae known to have occurred about 2.5 and 8 million years ago at about 50 pc distance. New and previously published atmospheric chemistry modeling results were combined with radiative transfer modeling to determine changes in surface-level solar irradiance and biological responses. We find that UVB irradiance is increased by a factor of 1.1 to 2.8, with large variation in latitude, and seasonally at high-latitude regions...
December 28, 2017: Astrobiology
https://www.readbyqxmd.com/read/29227156/the-characterization-of-biosignatures-in-caves-using-an-instrument-suite
#11
Kyle Uckert, Nancy J Chanover, Stephanie Getty, David G Voelz, William B Brinckerhoff, Nancy McMillan, Xifeng Xiao, Penelope J Boston, Xiang Li, Amy McAdam, David A Glenar, Arriana Chavez
The search for life and habitable environments on other Solar System bodies is a major motivator for planetary exploration. Due to the difficulty and significance of detecting extant or extinct extraterrestrial life in situ, several independent measurements from multiple instrument techniques will bolster the community's confidence in making any such claim. We demonstrate the detection of subsurface biosignatures using a suite of instrument techniques including IR reflectance spectroscopy, laser-induced breakdown spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy...
December 2017: Astrobiology
https://www.readbyqxmd.com/read/29227145/transport-induced-spatial-patterns-of-sulfur-isotopes-%C3%AE-34s-as-biosignatures
#12
Muammar Mansor, Khadouja Harouaka, Matthew S Gonzales, Jennifer L Macalady, Matthew S Fantle
Cave minerals deposited in the presence of microbes may host geochemical biosignatures that can be utilized to detect subsurface life on Earth, Mars, or other habitable worlds. The sulfur isotopic composition of gypsum (CaSO4·2H2O) formed in the presence of sulfur-oxidizing microbes in the Frasassi cave system, Italy, was evaluated as a biosignature. Sulfur isotopic compositions (δ34SV-CDT) of gypsum sampled from cave rooms with sulfidic air varied from -11 to -24‰, with minor deposits of elemental sulfur having δ34S values between -17 and -19‰...
December 11, 2017: Astrobiology
https://www.readbyqxmd.com/read/29195408/a-microfluidic-sub-critical-water-extraction-instrument
#13
Stewart Sherrit, Aaron C Noell, Anita Fisher, Mike C Lee, Nobuyuki Takano, Xiaoqi Bao, Thomas C Kutzer, Frank Grunthaner
This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction...
November 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29189763/formation-and-stability-of-prebiotically-relevant-vesicular-systems-in-terrestrial-geothermal-environments
#14
Manesh Prakash Joshi, Anupam Samanta, Gyana Ranjan Tripathy, Sudha Rajamani
Terrestrial geothermal fields and oceanic hydrothermal vents are considered as candidate environments for the emergence of life on Earth. Nevertheless, the ionic strength and salinity of oceans present serious limitations for the self-assembly of amphiphiles, a process that is fundamental for the formation of first protocells. Consequently, we systematically characterized the efficiency of amphiphile assembly, and vesicular stability, in terrestrial geothermal environments, both, under simulated laboratory conditions and in hot spring water samples (collected from Ladakh, India, an Astrobiologically relevant site)...
November 30, 2017: Life
https://www.readbyqxmd.com/read/29189043/an-antarctic-extreme-halophile-and-its-polyextremophilic-enzyme-effects-of-perchlorate-salts
#15
Victoria J Laye, Shiladitya DasSarma
Effects of perchlorate salts prevalent on the surface of Mars are of significant interest to astrobiology from the perspective of potential life on the Red Planet. Halorubrum lacusprofundi, a cold-adapted halophilic Antarctic archaeon, was able to grow anaerobically on 0.04 M concentration of perchlorate. With increasing concentrations of perchlorate, growth was inhibited, with half-maximal growth rate in ca. 0.3 M NaClO4 and 0.1 M Mg(ClO4)2 under aerobic conditions. Magnesium ions were also inhibitory for growth, but at considerably higher concentrations, with half-maximal growth rate above 1 M...
November 30, 2017: Astrobiology
https://www.readbyqxmd.com/read/29189040/organic-haze-as-a-biosignature-in-anoxic-earth-like-atmospheres
#16
Giada Arney, Shawn D Domagal-Goldman, Victoria S Meadows
Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8-2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and an M4V dwarf (GJ 876) and show that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates...
November 30, 2017: Astrobiology
https://www.readbyqxmd.com/read/29160728/selection-of-amino-acid-chirality-via-neutrino-interactions-with-14n-in-crossed-electric-and-magnetic-fields
#17
Michael A Famiano, Richard N Boyd, Toshitaka Kajino, Takashi Onaka
Previous work has suggested that the chirality of the amino acids could be established in the magnetic field of a nascent neutron star from a core-collapse supernova or massive collapsar. The magnetic field would orient the 14N nuclei, and the alignment of its nuclear spin with respect to those of the electron antineutrinos emitted from the collapsing star would determine the probability of destruction of the 14N nuclei by interactions with the antineutrinos. Subsequent work estimated the bulk polarization of the 14N nuclei in large rotating meteoroids in such an environment...
November 21, 2017: Astrobiology
https://www.readbyqxmd.com/read/29156444/survival-of-microbes-in-earth-s-stratosphere
#18
REVIEW
Priya DasSarma, Shiladitya DasSarma
The remarkable survival of microorganisms high above the surface of the Earth is of increasing interest. At stratospheric levels, multiple stressors including ultraviolet and ionizing radiation, low temperatures, hypobaric conditions, extreme desiccation, and nutrient scarcity are all significant challenges. Our understanding of which microorganisms are capable of tolerating such stressful conditions has been addressed by stratospheric sample collection and survival assays, through launching and recovery, and exposure to simulated conditions in the laboratory...
November 17, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/29148825/on-the-growth-and-detectability-of-land-plants-on-habitable-planets-around-m-dwarfs
#19
Duo Cui, Feng Tian, Yuwei Wang, Changshen Li, Chaoqing Yu, Le Yu
One signature of life on Earth is the vegetation red edge (VRE) feature of land plants, a dramatic change of reflectivity at wavelength near 0.7 μm. Potentially habitable planets around M dwarfs are tidally locked, which can limit the distribution of land plants. In this study, we used a biogeochemical model to investigate the distribution of land plants on potentially habitable planets around M dwarfs driven by climate data produced in a general circulation model (GCM). When considering the effects of clouds, the observation time needed for VRE detection on nearby p = 1 exoplanets around nearby M dwarfs is on the order of days using a 25 m(2) telescope if a large continent faces Earth during observations...
November 17, 2017: Astrobiology
https://www.readbyqxmd.com/read/29148823/space-dust-collisions-as-a-planetary-escape-mechanism
#20
Arjun Berera
It is observed that hypervelocity space dust, which is continuously bombarding Earth, creates immense momentum flows in the atmosphere. Some of this fast space dust inevitably will interact with the atmospheric system, transferring energy and moving particles around, with various possible consequences. This paper examines, with supporting estimates, the possibility that by way of collisions the Earth-grazing component of space dust can facilitate planetary escape of atmospheric particles, whether they are atoms and molecules that form the atmosphere or larger-sized particles...
November 17, 2017: Astrobiology
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