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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Evolution of the Early Earth and Its Biosphere

The history of life on Earth is a rich tapestry of adaptation and innovation which was shaped, at least in part, by the changing surface environment of our planet. To the extent that all rocky planets have followed similar evolutionary paths, studies of our own biosphere can guide us in our search for extraterrestrial life. Understanding the nature, timing, and causes of long-term changes in the global environment is a key objective.

DesMarais, David J.↗
NASA NTRS2000

Reduced Gas Cycling in Microbial Mats: Implications for Early Earth

For more than half the history of life on Earth, biological productivity was dominated by photosynthetic microbial mats. During this time, mats served as the preeminent biological influence on earth's surface and atmospheric chemistry and also as the primary crucible for microbial evolution. We find that modern analogs of these ancient mat communities generate substantial quantities of hydrogen, carbon monoxide, and methane. Escape of these gases from the biosphere would contribute strongly to atmospheric evolution and potentially to the net oxidation of earth's surface; sequestration within the biosphere carries equally important implications for the structure, function, and evolution of anaerobic microbial communities within the context of mat biology.

Hoehler, Tori M.↗
NASA NTRS1994

Use of Molecular Fossils for the Interpretation of Paleoenvironments on Early Earth: The Synthesis of Lipid Biomarkers by Methane-Oxidizing Bacteria

Over the course of Earth's history, the most important biological influence has come from the evolution of oxygenic photosynthesis and the development of an oxygen-rich biosphere. Although the availability of free oxygen had profound effects on subsequent biological and planetary evolution, clear paleobiological evidence of the timing of this transition is lacking. Recent technical advances in the microanalysis of organic matter has made it possible to detect residual molecules (biomarkers) in proterozoic (2.5 to 0.6 billion years) sedimentary rock characteristic of specific groups of microorganisms. When coupled with the carbon isotopic fractionations characteristic of biological systems and the new field of compound specific isotope analysis, biomarkers could prove to be a powerful tool for decoding ancient biochemistry from the geological record. We have been studying the carbon isotope fractionations associated with the synthesis of organic biomarker molecules in several types of methane-oxidizing bacteria that should have been key to carbon cycling in paleoenvironments after the evolution of oxygenic photosynthesis.

Jahnke, Linda L.↗
NASA NTRS1996

Searching for Life: Early Earth, Mars and Beyond

We might be entering a golden age for exploring life throughout time and space. Rapid gene sequencing will better define our most distant ancestors. The earliest geologic evidence of life is now 3.8 billion years old. Organic matter and submicron-sized morphologies have been preserved in the martian crust for billions of years. Several new missions to Mars are planned, with a high priority on the search for life, past or present. The recent discovery of large extrasolar planets has heightened interest in spacecraft to detect small, earth-like planets. A recent workshop discussed strategies for life detection on such planets. There is much to anticipate in the near future.

DesMarais, David J.↗
NASA NTRS1997

Glycolonitrile oligomerization: structure of isolated oxazolines, potential heterocycles on the early earth

A study of glycolonitrile polymerization has led to the isolation and characterization of two 2,5-dihydro-4-aminooxazoles, 4 and 5. Previous reports have misassigned these structures as s-triazines or pyrimidines. X-ray diffraction analysis of crystals of 4 and an acetylated oxazole derivative of 5 (6) confirm the proposed structures. Ab initio computations are used to assess the relative thermodynamic stability of three trimer isomers (an s-triazine, an aminohydroxypyrimidine, and an aminooxazoline), and the results indicate that 4 is a novel kinetic product. Mechanistic considerations rationalize kinetic oxazole formation over the more customary triazine or pyrimidine trimers.

Non-NASA Center↗
NASA NTRS2004

Biogeochemical Cycles of Carbon and Sulfur on Early Earth (and on Mars?)

The physical and chemical interactions between the atmosphere, hydrosphere, geosphere and biosphere can be examined for elements such as carbon (C) and sulfur (S) that have played central roles for both life and the environment. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. These multiple roles of C and S interact across a network of elemental reservoirs interconnected by physical, chemical and biological processes. These networks are termed biogeochemical C and S cycles.

DesMarais, D. J.↗
NASA NTRS2006

Prebiotic materials from on and off the early Earth

One of the great puzzles of all time is how did life arise? It has been universally presumed that life arose in a soup rich in compounds made mostly of carbon, the kind of which we are currently composed. Where did these organic molecules come from? In this talk I will review proposed contributions to pre-biotic organic chemistry from both terrestrial processes (i.e., hydrothermal vents, Miller-Urey syntheses) and also from space. While the former is perhaps better known and more commonly taught in school, we now know that comet and asteroid dust deliver tons of organics to the Earth every day, and there is a growing consensus among scientists that molecules from space played an important role in making the Earth habitable, and perhaps even provided specific compounds that were directly related to the origin of life.

Bernstein, Max↗
NASA NTRS2011

Composition of LHB Comets and Their Influence on the Early Earth Atmosphere Composition

Two main processes were responsible for the composition of this atmosphere: chemical evolution of the volatile fraction of the accretion material forming the planet and the delivery of gasses to the planetary surface by impactors during the late heavy bombardment (LHB). The amount and composition of the volatile fraction influences the outgassing of the Earth mantle during the last planetary formation period. A very weakened form of outgassing activity can still be observed today by examining the composition of volcanic gasses. An enlightenment of the second process is based on the sparse records of the LHB impactors resulting from the composition of meteorites, observed cometary comas, and the impact material found on the Moon. However, for an assessment of the influence of the outgassing on the one hand and the LHB event on the other, one has to supplement the observations with numerical simulations of the formation of volatiles and their incorporation into the accretion material which is the precursors of planetary matter, comets and asteroids. These simulations are performed with a combined hydrodynamic-chemical model of the solar nebula (SN). We calculate the chemical composition of the gas and dust phase of the SN. From these data, we draw conclusions on the upper limits of the water content and the amount of carbon and nitrogen rich volatiles incorporated later into the accretion material. Knowing these limits we determine the portion of major gas compounds delivered during the LHB and compare it with the related quantities of the outgassed species.

Tornow, C.↗
NASA NTRS2015

Environmental Consequences of Big Nasty Impacts on the Early Earth

The geological record of the Archean Earth is spattered with impact spherules from a dozen or so major cosmic collisions involving Earth and asteroids or comets (Lowe, Byerly 1986, 2015). Extrapolation of the documented deposits suggests that most of these impacts were as big or bigger than the Chicxulub event that famously ended the reign of the thunder lizards. As the Archean impacts were greater, the environmental effects were also greater. The number and magnitude of the impacts is bounded by the lunar record. There are no lunar craters bigger than Chicxulub that date to Earth's mid-to-late Archean. Chance dictates that Earth experienced no more than approximately 10 impacts bigger than Chicxulub between 2.5 billion years and 3.5 2.5 billion years, the biggest of which were approximately30-100 times more energetic, comparable to the Orientale impact on the Moon (1x10 (sup 26) joules). To quantify the thermal consequences of big impacts on old Earth, we model the global flow of energy from the impact into the environment. The model presumes that a significant fraction of the impact energy goes into ejecta that interact with the atmosphere. Much of this energy is initially in rock vapor, melt, and high speed particles. (i) The upper atmosphere is heated by ejecta as they reenter the atmosphere. The mix of hot air, rock vapor, and hot silicates cools by thermal radiation. Rock raindrops fall out as the upper atmosphere cools. (ii) The energy balance of the lower atmosphere is set by radiative exchange with the upper atmosphere and with the surface, and by evaporation of seawater. Susequent cooling is governed by condensation of water vapor. (iii) The oceans are heated by thermal radiation and rock rain and cooled by evaporation. Surface waters become hot and salty; if a deep ocean remains it is relatively cool. Subsequently water vapor condenses to replenish the oceans with hot fresh water (how fresh depending on continental weathering, which might be rather rapid under the circumstances). (iv) The surface temperature of dry land is presumed to be the same as the lower atmosphere. A thermal wave propagates into the land at a rate set by conduction. Impacts not greatly larger than Chicxulub can raise the surface temperature by tens, hundreds, or even thousands of degrees, and evaporate meters to hundreds of meters of water. The biggest should have vitrified exposed dry land. More results are for the talk, as here we have run out of space.

asteroids↗
NASA NTRS2015

Environmental Consequences of Big Nasty Impacts on the Early Earth

The geological record of the Archean Earth is spattered with impact spherules from a dozen or so major cosmic collisions involving Earth and asteroids or comets (Lowe, Byerly 1986, 2015). Extrapolation of the documented deposits suggests that most of these impacts were as big or bigger than the Chicxulub event that famously ended the reign of the thunder lizards. As the Archean impacts were greater, the environmental effects were also greater. The number and magnitude of the impacts is bounded by the lunar record. There are no lunar craters bigger than Chicxulub that date to Earth's mid-to-late Archean. Chance dictates that Earth experienced no more than approximately 10 impacts bigger than Chicxulub between 2.5 billion years and 3.5 billion years, the biggest of which were approximately 30-100 times more energetic, comparable to the Orientale impact on the Moon (1x10 (sup 26) joules). To quantify the thermal consequences of big impacts on old Earth, we model the global flow of energy from the impact into the environment. The model presumes that a significant fraction of the impact energy goes into ejecta that interact with the atmosphere. Much of this energy is initially in rock vapor, melt, and high speed particles. (i) The upper atmosphere is heated by ejecta as they reenter the atmosphere. The mix of hot air, rock vapor, and hot silicates cools by thermal radiation. Rock raindrops fall out as the upper atmosphere cools. (ii) The energy balance of the lower atmosphere is set by radiative exchange with the upper atmosphere and with the surface, and by evaporation of seawater. Susequent cooling is governed by condensation of water vapor. (iii) The oceans are heated by thermal radiation and rock rain and cooled by evaporation. Surface waters become hot and salty; if a deep ocean remains it is relatively cool. Subsequently water vapor condenses to replenish the oceans with hot fresh water (how fresh depending on continental weathering, which might be rather rapid under the circumstances). (iv) The surface temperature of dry land is presumed to be the same as the lower atmosphere. A thermal wave propagates into the land at a rate set by conduction. Impacts not greatly larger than Chicxulub can raise the surface temperature by tens, hundreds, or even thousands of degrees, and evaporate meters to hundreds of meters of water. The biggest should have vitrified exposed dry land. More results are for the talk, as here we have run out of space.

Archean Earth↗
NASA NTRS2017

PHYS: Division of Physical Chemistry 258 - Properties and Origins of Cometary and Asteroidal Organic Matter Delivered to the Early Earth

Comets and asteroids may have contributed much of the Earth's water and organic matter. The Earth accretes approximately 4x10(exp 7) Kg of dust and meteorites from these sources every year. The least altered meteorites contain complex assemblages of organic compounds and abundant hydrated minerals. These carbonaceous chondrite meteorites probably derive from asteroids that underwent hydrothermal processing within the first few million years after their accretion. Meteorite organics show isotopic and chemical signatures of low-T ion-molecule and grain-surface chemistry and photolysis of icy grains that occurred in cold molecular clouds and the outer protoplanetary disk. These signatures have been overprinted by aqueously mediated chemistry in asteroid parent bodies, forming amino acids and other prebiotic molecules. Comets are much richer in organic matter but it is less well characterized. Comet dust collected in the stratosphere shows larger H and N isotopic anomalies than most meteorites, suggesting better preservation of primordial organics. Rosetta studies of comet 67P coma dust find complex organic matter that may be related to the macromolecular material that dominates the organic inventory of primitive meteorites. The exogenous organic material accreting on Earth throughout its history is made up of thousands of molecular species formed in diverse processes ranging from circumstellar outflows to chemistry at near absolute zero in dark cloud cores and the formative environment within minor planets. NASA and JAXA are currently flying sample return missions to primitive, potentially organic-rich asteroids. The OSIRIS-REx and Hayabusa2 missions will map their target asteroids, Bennu and Ryugu, in detail and return regolith samples to Earth. Laboratory analyses of these pristine asteroid samples will provide unprecedented views of asteroidal organic matter relatively free of terrestrial contamination within well determined geological context. Studies of extraterrestrial materials and returned samples are essential to understand the origins of Solar System organic material and the roles of comets and asteroids to providing the starting materials for the emergence of life.

Messenger, Scott↗
NASA NTRS2018

Early Earth and Rocky Extrasolar Planet Characterization

Scientists are currently designing instruments, telescopes, and spacecraft to search for evidence of life beyond Earth. This search for life beyond Earth comes with an expectation to detect life that is different than the life found on modern-day Earth. But scientists will also be expected to provide compelling proof behind any claims that we are not alone. These two expectations are seemingly at odds with each other, because it will be easiest to provide compelling evidence for life when we have a deep understanding of the life we are looking at.The study of Earth history provides a means to reconcile this tension. Different periods of Earth history present us with biospheres that are dramatically different from modern-day Earth, but for which we have abundant data. This informs our understanding of habitability, because of the variety of global chemical and climatic conditions in Earth history for which we know life has thrived. The study of Earth history also informs our understanding of how to detect life; as the global influences of life have completely changed, so have the detectable features of Earth's biosphere.The appreciation of our home planet as a tightly coupled system also provides us top-level lessons for how to search for an even broader set of biospheres with a wider variety of detectable features. The study of Earth history has taught us that life is a both a function of and critical forcing on the planetary environment. Numerical models of these interactions can by driven by our understanding of Earth history, and be validated against the geological and geochemical data. These models can then be applied to a wider variety of planetary conditions. This will help scientists determine what kinds of life are possible, and eventually help them recognize and confirm the presence of life on rocky planets around other stars.

Domagal-Goldman, Shawn D.↗
NASA NTRS2000

The Geologic History of Mars: An Astrobiology Perspective

Fourteen SNC meteorites contain information which must be incorporated with recent spaceflight data for developing Mars' geologic history. SNCs have crystallization ages of 4500 to 160 m.y. Tle oldest meteorite ALH84001 contains information on the Noachian period of Mars' history. There are no meteorites from the Hesperian period and the remaining 13 meteorites fall into two age groups within the Amazonian: The nakhlites around 1300 m.y. and the shergottites between 800-160 m.y. Oxygen isotopic analysis of Martian samples shows two distinct O2 reservoirs throughout Martian history indicating late additions of volatiles and a lack of plate tectonics prior to 3.9 Gy. Evidence for percolation of aqueous brines through impact-produced fractures in the rocky surface is contained in the 3.9 Gy-old ALH84001 carbonate deposits. These carbonates precipitated at approx. 100 C. At this time life had already evolved on Earth. Early Mars could have hosted life similar to the bacteria that inhabited early Earth. Potential microorganisms could have been transported into fractures by carbonate-bearing waters and their remains could have become incorporated into the precipitated carbonate. Since Mars had a weak magnetic field at this time, it can be hypothesized that some of the Martian microorganisms may have been similar to terrestrial magnetotactic bacteria. Over geologic time episodic cratering, and tectonic events have occurred on Mars along with the periodic release of subsurface waters which may have produced clays within SNC meteorites. The geochemical data contained within SNC meteorites complements previous observational data and the recent Mars Global Surveyor data to provide a geological and environmental history which spans almost the entire lifespan on Mars. One of the outstanding features of this model is the possible creation of an early (about 4 Gy) volatile reservoir distinct from the outgassed Mars volatiles, and the persistence of this reservoir throughout most, if not all of subsequent Mars' history. Within the framework of this history a potential scenario for a possible record of living organisms is provided by suggestive structures and organic signatures trapped within secondary mineral deposits and alteration features of some SNC meteorites. Tracing the differences in oxygen isotopic compositions within Martian components allows us to gain insight in the history of Mars.

Gibson, Everett K.↗
NASA NTRS1983

The chemical composition and climatology of the earth's early atmosphere

The earth's climate as it relates to the evolution of life is discussed.. Seven fundamental characteristics of the early evolutionary environment are examined, including a carbon dioxide and water vapor atmosphere, atmospheric mass between 500 and 1000 mb, a global hydrosphere, lowered solar luminosity, hospitable average global temperatures, a convectively active atmosphere, and trace gases. The influence of the early earth's extensive hydrosphere on the origin of life is considered. The warming of that hydrosphere due to radiative fluxes and the greenhouse effect is examined, and the nature of the feedback between clouds and climate is addressed.

Henderson-Sellers, A.↗