Fourth Symposium on Chemical Evolution and the Origin and Evolution of Life

This symposium was held at the NASA Ames Research Center, Moffett Field, California, July 24-27, 1990. The NASA exobiology investigators reported their recent research findings. Scientific papers were presented in the following areas: cosmic evolution of biogenic compounds, prebiotic evolution (planetary and molecular), early evolution of life (biological and geochemical), evolution of advanced life, solar system exploration, and the Search for Extraterrestrial Intelligence (SETI)

Nitriles in Prebiotic Chemistry and Astrobiology

Life appeared on Earth within a billion years of the planet’s formation. How? - no one knows. Theories regarding the origin of life involve reactions of molecules predicted to have existed on early Earth in what is called prebiotic chemistry. In this thesis, I use computational methods to investigate hypotheses in prebiotic chemistry and astrobiology. With computational chemistry, it is possible to predict the thermodynamics and kinetics of chemical processes. The long-term goal of this line of research is furthering our understanding of the origin of life.The first part of this thesis is devoted to hydrogen cyanide (HCN) chemistry. HCN is believed to have been present on early Earth. Molecular building blocks of DNA, RNA, and proteins have been detected among HCN reaction products. However, because of HCN’s reactivity, the molecule forms numerous other compounds as well. One such set of proposed reaction products are HCN-derived polymers - a diverse group of structures which have been proposed to form in many ways. Here I present a thermodynamic landscape of HCN-derived molecules and polymers. Using the thermodynamic map, some hypothesized reaction pathways are proven to be unfeasible. Polyaminoimidazole is estimated to be one of the most stable polymers, while the nucleobase adenine is computed as the most stable of all studied structures. We also investigate the first steps in the formation of two proposed HCN reaction products: diaminomaleonitrile and polyimine. Our results reveal that all studied competing reactions have similar activation barriers. These results open for the possibility of a diverse beginning to HCN oligomerization under kinetic control. The estimated timescale of HCN oligomerization suggests that reactions in low-temperature environments as cold as 200 K could occur within thousands of years. I discuss the implications of the predicted reaction rates for HCN chemistry in astrochemical environments like comets and Saturn’s moon Titan. The second part of the thesis investigates an astrobiological hypothesis: the possibility for cryogenically operable membranes in the seas of Titan. It is concluded that a previously suggested polarity-inverted membrane made from acrylonitrile, a so-called azotosome, cannot spontaneously self-assemble and is therefore unlikely to exist on Titan

Second Symposium on Chemical Evolution and the Origin of Life

Recent findings by NASA Exobiology investigators are reported. Scientific papers are presented in the following areas: cosmic evolution of biogenic compounds, prebiotic evolution (planetary and molecular), early evolution of life (biological and geochemical), evolution of advanced life, solar system exploration, and the Search for Extraterrestrial Intelligence (SETI)

Sixth Annual NASA Ames Space Science and Astrobiology Jamboree

Welcome to the Sixth Annual NASA Ames Research Center, Space Science and Astrobiology Jamboree at NASA Ames Research Center (ARC). The Space Science and Astrobiology Division consists of over 60 Civil Servants, with more than 120 Cooperative Agreement Research Scientists, Post-Doctoral Fellows, Science Support Contractors, Visiting Scientists, and many other Research Associates. Within the Division there is engagement in scientific investigations over a breadth of disciplines including Astrobiology, Astrophysics, Exobiology, Exoplanets, Planetary Systems Science, and many more. The Division's personnel support NASA spacecraft missions (current and planned), including SOFIA, K2, MSL, New Horizons, JWST, WFIRST, and others. Our top-notch science research staff is spread amongst three branches in five buildings at ARC. Naturally, it can thus be difficult to remain abreast of what fellow scientific researchers pursue actively, and then what may present and/or offer regarding inter-Branch, intra-Division future collaborative efforts. In organizing this annual jamboree, the goals are to offer a wholesome, one-venue opportunity to sense the active scientific research and spacecraft mission involvement within the Division; and to facilitate communication and collaboration amongst our research scientists. Annually, the Division honors one senior research scientist with a Pollack Lecture, and one early career research scientist with an Outstanding Early Career Space Scientist Lecture. For the Pollack Lecture, the honor is bestowed upon a senior researcher who has made significant contributions within any area of research aligned with space science and/or astrobiology. This year we are pleased to honor Linda Jahnke. With the Early Career Lecture, the honor is bestowed upon an early-career researcher who has substantially demonstrated great promise for significant contributions within space science, astrobiology, and/or, in support of spacecraft missions addressing such disciplines. This year we are pleased to honor Amanda Cook. We hope that you will make time to join us for the day in meeting fellow Division members, expanding knowledge of our activities, and creating new collaborations within the Space Science and Astrobiology Division

Biosignature storage in sulfate minerals- synthetic and natural investigations of the jarosite group minerals

The discovery of jarosite on Mars in 2004 generated increased interest in the properties of the mineral related to the search for life on other planets. Several studies indicate that the formation of jarosite can be linked to biological activity on Earth and biomolecules such as amino acids have been found associated with terrestrial jarosite samples. A series of natural and synthetic investigations using different jarosite end-members has been conducted and is presented in this dissertation to investigate the possibility that jarosite can store biosignatures. Natural samples were analyzed by x-ray diffraction, elemental carbon analysis and laser-desorption Fourier transform mass spectrometry (LD-FTMS) and were found to contain the amino acid glycine. Synthetic experiments were conducted in which the different end-members were synthesized in the presence of glycine as well as the amino acid alanine and the amino acid breakdown product methylamine. These samples were analyzed by x-ray diffraction, neutron diffraction, LD-FTMS and thermogravimetric analysis (TGA) techniques. Results of these experiments show that the detection of the biosignature and the effect that biomolecule has on the jarosite minerals is dependent on the end-member and indicate that the jarosite minerals are an excellent target for detecting potential signs of past life on other planets

Experimentální studium chemické evoluce biomolekul v podmínkách rané Země

Vznik života na Zemi je jedním z prázdných míst lidského vědění. Tato práce je zaměřena na odhalení několika dílků této skládačky. Prezentujeme současný stav poznání zejména ve spojení se syntézou biomolekul za prebiotických podmínek. V této práci jsou předloženy výsledky experimentů, jež naznačují, že neutrální planetární atmosféra obsahující představitele vulkanických plynů (CO2, N2, H2O) může být působením měkkého UV záření v přítomnosti minerálních katalyzátorů přeměněna na relativně reaktivní směs redukovaných plynů (CH4, CO). Ty mohou být dále transformovány vysoce energetickými procesy za vzniku biomolekul. Směs CH4, CO + N2 představuje prototyp běžné redukční atmosféry, jíž podobné lze nalézt např. na Titanu, největším Saturnově měsíci, nebo také v minulosti na naší planetě coby tzv. sekundární atmosféru. V následných experimentech byla ekvimolární směs CH4 : CO : N2 v přítomnosti vodní páry exponována vysoce energetickému plazmatu, jež simuluje dopad asteroidu - jednu ze série impaktních událostí, kterým byla raná Země vystavena během prvních 600 milionů let své existence. Po dodání celkové energie 3250 J v laserových pulzech byla zjištěna přítomnost organických molekul důležitých pro prebiotickou chemii. Mezi nimi jsou např. báze ribonukleové kyseliny (adenin, uracil, guanin, cytosin),...Origin of life is a still-enduring gap in human knowledge. This work is focused on revealing of several pieces of this puzzle. State of the art scenarios of biomolecules synthesis under prebiotic conditions are presented and discussed. This thesis presents our recent experiments suggesting a novel idea that neutral planetary atmosphere containing a mixture of neutral volcanic-type gasses (CO2, N2, H2O) can be converted over acidic mineral catalysts upon irradiation by a soft UV-radiation into a relatively reactive mixture of reducing gases (CH4, CO), which can be further reprocessed by high-energy chemistry. The resulting mixture (CH4, CO + N2) represents a common reducing atmosphere related e.g. to the chemistry of Titan, the largest moon of Saturn, as well as a possible representation of the secondary atmosphere of our planet. Also, photocatalytic reduction of CO2-rich atmosphere can explain the abiotic origin of methane on current Mars or other terrestrial planets. In our subsequent experiments, corresponding equimolar model mixture of CH4 : CO : N2 in presence of water vapour was subjected to reprocessing by high-power laser plasma simulating an asteroid impact - one of a series of impact events which the young Earth experienced during the first 600 million years of her history. Upon delivery...Katedra fyzikální a makromol. chemieDepartment of Physical and Macromolecular ChemistryPřírodovědecká fakultaFaculty of Scienc

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 360)

This bibliography lists 217 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during February 1992. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

5th Annual NASA Ames Space Science and Astrobiology Jamboree

No abstract availabl

Ice structures, patterns, and processes: A view across the ice-fields

We look ahead from the frontiers of research on ice dynamics in its broadest sense; on the structures of ice, the patterns or morphologies it may assume, and the physical and chemical processes in which it is involved. We highlight open questions in the various fields of ice research in nature; ranging from terrestrial and oceanic ice on Earth, to ice in the atmosphere, to ice on other solar system bodies and in interstellar space

The Origin and Early Evolution of Life

What is life? How, where, and when did life arise? These questions have remained most fascinating over the last hundred years. Systems chemistry is the way to go to better understand this problem and to try and answer the unsolved question regarding the origin of Life. Self-organization, thanks to the role of lipid boundaries, made possible the rise of protocells. The role of these boundaries is to separate and co-locate micro-environments, and make them spatially distinct; to protect and keep them at defined concentrations; and to enable a multitude of often competing and interfering biochemical reactions to occur simultaneously. The aim of this Special Issue is to summarize the latest discoveries in the field of the prebiotic chemistry of biomolecules, self-organization, protocells and the origin of life. In recent years, thousands of excellent reviews and articles have appeared in the literature and some breakthroughs have already been achieved. However, a great deal of work remains to be carried out. Beyond the borders of the traditional domains of scientific activity, the multidisciplinary character of the present Special Issue leaves space for anyone to creatively contribute to any aspect of these and related relevant topics. We hope that the presented works will be stimulating for a new generation of scientists that are taking their first steps in this fascinating field