Missed the last seminar series?
See below for a list of past UWAB seminars, including video recordings (when available).
Approximately half a dozen short presentations by UW Astrobiology faculty and students.
Formation and Detection of Habitable Exomoons
While about 4,000 planets and planet candidates have been found outside the solar system, no moon around an exoplanet (or "exomoon") has been found so far. New simulations indicate that moons similar in mass to planet Mars exist around the biggest planets outside the solar system, and recent advances in exomoon searching methods suggest that these large moons are observable with current and near-future technology. The detection of these moons would not only provide extremely valuable insights into planet formation and evolution, but could also reveal a recently predicted class of Mars-mass moons in the stellar habitable zones. These moons would be several times as massive as Ganymede, the most massive moon in the solar system, and they could be abundant extrasolar habitats with odd day-night cycles.
Is there Methane on Mars? III. Revenge of the Cows
The quest to measure methane has become a driver of 21st century Mars science. Dr. Zahnle will review why the published reports of methane on Mars should be regarded with skepticism, before addressing why the question may never go away.
The rise (and fall) of oxygen in Earth’s oceans and atmosphere and the co-evolution of early life
The oldest signs of animal life appear in the geologic record 600 to 700 million years ago. For the four billion years prior, our planet experienced dramatic changes that paved the way for this milestone. Beyond the establishment of the Earth’s earliest oceans perhaps as early as 4.4 billion years ago (Ga), the single most important environmental transformation in history may have been the first permanent rise of atmospheric oxygen around 2.3 to 2.4 Ga, at the so-called Great Oxidation Event (GOE). Before then, Earth’s atmosphere and oceans were virtually devoid of this gas, which forms the basis for all macroscopic life. Yet key questions remain about the timing and triggers of the first biological O2 production, now tentatively placed at 3 Ga, and the first appearance of animals almost two-and-half-billion years later. This talk will lay out the history of early oxygenation with an emphasis on the long delay between initial oxygenation and the expansion of complex life.
Recent work suggests that the initial rise of oxygen may have been protracted, occurring in fits and starts rather than a single step—and that once permanently present in the atmosphere, oxygen likely rose to very high levels and then plummeted. At least a billion years of dominantly oxygen-free conditions in the deep ocean followed beneath an atmosphere and shallow ocean that may still have been oxygen lean. Oxygen and associated nutrient deficiencies may, in turn, have set a challenging course for many of the ocean’s simple microscopic inhabitants, including persistently low populations and diversities of the earliest eukaryotic organisms. The newest data suggest that these billion-plus years of ‘intermediate’ oxygen and life were followed by increases in ocean/atmosphere oxygen contents and eukaryotic diversity that appear to anticipate the famous snowball Earth glaciation that began roughly 700 million years ago. The discussion will emphasize new proxy perspectives on these evolving redox conditions and their cause-and-effect relationships with early life.
Seeing Through the Clouds: The Thermal Emission and Reflected Light of Super-Earths with Flat Transmission Spectra
Vast resources have been dedicated to characterizing the handful of planets with radii between Earth’s and Neptune’s that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Of the ~four small planets studied to date, all have radii in the near-IR consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. I will explore the types of clouds and hazes that can completely obscure transmission spectra. I will then show the effect that these thick clouds have on the thermal emission and reflected light spectra of small exoplanets. I present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can potentially break the degeneracies and better constrain the atmospheric compositions.
Self-Organizing Chemical Systems: From Materials Science to Astrobiology
Self-organizing processes in chemical reaction/precipitation systems can lead to a variety of complex structures, including chemical gardens and inorganic membranes. They key aspects of these systems are the steep concentration gradients and far-from-equilibrium conditions, which in turn are determined by environmental and chemical factors. Chemical garden systems form complex self-organized structures and are now known to have many interesting and useful aspects, such as the ability to generate electrochemical energy and act as catalysts, and there is much interest in learning to control the precipitation process in such systems in order to produce useful materials. Chemical garden precipitates exist in nature as well, including hydrothermal chimneys, which form at the interface of contrasting seawater and vent fluids. Seafloor hydrothermal systems generate disequilibria through water-rock reactions in the form of redox, pH, chemical and thermal gradients; and the inorganic precipitates formed in these gradients could have played a role in prebiotic chemistry and the origin of life on the early Earth, and also could affect habitability and energy availability on other worlds with water-rock interfaces.
Wolf Clifton (Graduate Student, University of Washington)
Research Rotation Presentation: Growth of Cold-Adapted Bacteria Under Different Pressures and Temperatures
The subsurface ocean of Jupiter’s moon Europa is considered to be among the best prospective habitats for extraterrestrial life in our solar system. However, it is not known whether Earth organisms can grow at Europan seafloor pressures, which by many estimates exceed the maximum hydrostatic pressure observed in Earth’s oceans. Previous studies have shown a synergistic relationship between high temperature and high pressure tolerance for several organisms, suggesting that the warming effect of hydrothermal systems on the Europan seafloor could enable microbial growth under the high pressures experienced there. This rotation project sought to test the hypothesis that increased temperature boosts growth at high pressures for cold-adapted marine bacteria, using the organisms Colwellia psychrerythraea 34H and Psychrobacter strain P7E. These organisms were incubated at several combinations of temperature (8 and 18o C) and pressure (200, 400, and 600 atm), with cell counts taken periodically to measure growth over time. A synergistic relationship between temperature and pressure tolerance was observed for P7E, which grew better at 400 atm if the temperature was elevated to 18oC. No synergistic relationship was observed for 34H; nonetheless, the results are significant for demonstrating that 34H can grow at higher pressures than previously observed. Although the project’s findings do not directly address the question of whether Earth-like life can grow under Europan seafloor pressures, which greatly exceed those tested in this experiment, the results offer several insights relevant to astrobiology that may inform the design of future studies testing conditions for habitability in the Europan ocean and other high-pressure extraterrestrial environments.
Steven Wood (Research Assistant Professor, University of Washington)
Evidence, Explanation, and Implications for Recent, Cyclic, 20x Variation in the Mass of the Martian Atmosphere
The obliquity, or tilt, of Mars' spin axis is currently 25.19°, similar to that of the Earth, and seasonal variation in polar temperatures cause CO2 - which makes up 95% of the atmosphere - to condense each winter and form a seasonal "cap" of CO2 ice about 1 to 2 m thick. This cap evaporates away in spring and this cycle causes a 20% variation in the global average surface pressure which was first predicted by Leighton and Murray in 1966 and confirmed by the Viking Landers.
Construction and Destruction of Mountains on Mars
stability. Mars’ sedimentary record is the only known archive of a major planetary habitability transition. No rivers flow on today's Mars, but rovers and orbiters have found >3 Ga-old sedimentary rocks, dry rivers and paleolakes, and aqueous minerals. The nature of the early wet era, the processes that allowed surface liquid water, and the cause of climate deterioration are all unknown.
The "Curiosity" rover is currently exploring the moat encircling a 5km-high sedimentary rock mound in Gale Crater. This moat-and-mound pattern is common in Mars craters and canyons, but its origin is unknown. I will set out the evidence that moats and mounds grew together, shaped by slope winds down the crater and mound flanks, and discuss the implications for liquid water sources on early Mars and for Mars habitability. If time allows, I will discuss ongoing work on connections between time gaps in the Mars sedimentary record (including at Gale Crater) and climate modelling of late bursts of habitability on Mars.
Research Rotation Presentation: Measuring Gas Production by Anoxygenic Photrophic Bacteria
The success of detecting life on another planet is contingent upon our understanding of possible biosignatures. In recent years, research has focused on O2 and O3 as candidates for gaseous biosignatures. But it is not just O2-producers who call Earth home. Microorganisms have dominated Earth for around 80% of its history, and among the most primitive organisms are anoxygenic phototrophs – microbes that use electron donors other than water and do not produce oxygen. Currently, there are no known observable biosignature gases produced by these organisms. During my research rotation, I worked with Dr. Niki Parenteau, at NASA Ames Research Center, to characterize gas production by anoxygenic photrophs using a membrane-inlet mass spectrometer newly-acquired by the Ames group. We initially focused on biogenic S gases that can form from small molecular weight organic compounds produced by the phototrophs combining with sulfide. We calibrated the instrument and then measured gas production from two samples: 1) a culture of purple non-sulfur bacteria and 2) an environmental sample of purple sulfur bacteria that we collected from a sulfidic hot spring in northern California. We observed distinct changes in gas production as we exposed them to oscillating conditions of darkness and light. We conclude the new mass spectrometer looks promising for doing further analysis on gas production from other microbial cultures and natural communities. An unexpected result was that the culture of purple non-sulfur bacteria produced CO2 when exposed to light. The origin of this CO2 remains unknown and deserves further investigation.
Donald Brownlee (Professor, University of Washington)
The role of interstellar molecules and large-scale mixing in making habitable planets
The laboratory study of collected comet samples indicate that interstellar solids were largely destroyed during the formation of the solar system and that it is unlikely that interstellar molecules played a significant role in the origin of life on Earth. Nearly all of the rocky components (most of their mass) of the solar system’s original ice-rich planetesimals appear to have formed at high temperatures in hot inner nebula regions by the same processes that made the best preserved nebular materials found in primitive meteorites. The dispersion of isotopic and minor element compositions of comet silicates differs from what is found in meteorites, suggesting that distant solar system bodies contain an averaged mix of inner solar system materials. These materials were derived from a broad range of nebular regions and transported over great distances. The data suggest that comet accretion times were longer than nebular mixing times, in contrast to meteorites that retain regional properties because they accreted faster than solids could be mixed between nebular regions. These results shed new insight into the mystery of why carbon and water are two orders of magnitude less abundant in terrestrial planets than they are in comets, the dominant class of early solar system planetesimal.
Choose Your Own Adventure: Multiplicity of Planets among the Kepler M Dwarfs
Life, Jim, but Not as We Know It: Prospects for Life in Titan's Hydrocarbon Seas
From Iceland to Titan and beyond: Using laboratory investigations and analogue field sites to explore the boundaries of prebiotic and biotic
In parallel, an international collaboration inspired by the 2012 NASA Nordic Astrobiology Summer School, successfully completed a field expedition to Iceland to test life detection techniques and decision-making strategies in a Mars-like analogue environment. We discovered that habitability and microbial diversity may vary widely, even in areas that appear to be geologically homogeneous. This has implications for field sampling and analysis of volcanic regions on Mars. Sampling strategies should target as many spatially separated sites as practical to improve the chances of detecting life.
Modeling of serpentinization driven hydrothermal circulation on icy satellites
Hydrothermal systems on Earth are often environmental niches highly favorable to microbial life. In particular, hydrothermal systems driven by exothermic serpentinization reactions are able to sustain themselves via predominantly geochemical drivers, even in the absence of magmatic or other heat sources from below. Significant work has been done studying these terrestrial systems, specifically in trying to understand what factors control how much heat in a particular system stems from serpentinization. For her astrobiology rotation project, Elena went to the Jet Propulsion Laboratory to work with AB program alum, Dr. Steve Vance, to model how serpentinizing systems might behave on icy satellites like Enceladus and Europa. She will present how they approached this question and their initial results.
Veteran's Day. No colloquium.
Earliest Earth to the Origin of Life
The present Earth-Moon system formed in the wake of the collision of a Mars-sized and Venus-sized planet. Tides strongly heated the interior of the Earth. A massive C)2 and water atmosphere blanketed the Earth. Choline and sulfur species made it opaque so heat escaped at the runaway greenhouse threshold. After ~10 m.y, the interior froze and water rained out. The surface temperature was ~200C and the CO2 pressures was ~200 bars. The Earth did not become inhabitable until the CO2 subducted into the mantle. Arc volcanics formed from CO2-rich oceanic crust. They were K-rich peralkaline and strongly reducing. Fluids in these rocks tend to stabilize ribose aiding production of RNA. This environment adds to the tradition serpentine environement under the ocean and on land. It may have left tracks in modern life The ocean may well have had K/Na much greater than present, like cellular fluids. BY ~3.8 Ga, the climate was clement and CO2 near modern levels. Subducted material in the mantle may preserve evidence, but none has been found to date.
The origin of microbial species: Peering into microbial genomes to understand microbial adaptation into new ecological niches
Metal and Metalloid Tolerance Mechanisms of Metal Hyperaccumulator Plants and their Applications for Human Extraterrestrial Colonies
Worldwide more than 400 plant species have evolved the extreme ability to hyperaccumulate the following elements in their shoots; metals (nickel, zinc, cadmium, cobalt, or manganese) the metalloids (arsenic and selenium). Of these species, almost one-quarter are Brassicaceae family members, including numerous species that hyperaccumulate metals up to 3% of shoot dry weight. Brassicaceae model species have been developed to study the molecular mechanisms of metal tolerance and hyperaccumulation and our recent findings hold promise for improving plant growth in metal enriched environments which is useful for rhizofiltration of water, phytoremediation of soils and for increasing the mineral nutrition of crop plants. The knowledge gained by researching metal hyperaccumulator plants clearly holds potential value for developing plant based applications for use in the phytoremediation of earth’s polluted environments and also for use in developing bioengineered life support systems required for long term manned space travel and for in situ resource utilization (ISRU), which are required processes for the long term human colonization of extraterrestrial planetary bodies.
Modeling The Climate Effects of Deccan Traps Flood Volcanism (UWAB Research Rotation Presentation)
Measuring Interdisciplinarity Using Citations (UWAB Research Rotation Presentation)
Characterizing A New Kind of Exoplanet: Low-Mass Low-Density Exoplanets
Bulk Composition and Habitability of Sub-Neptune-Size Exoplanets
The Origins of the Moon, Rise of Atmospheric Oxygen, Volcanic Eruption, and Continental Weathering: A Non-Traditional Isotope Perspective
Microbial Systems: Nexus roles for Astrobiology, Energy and Space
Remote Sensing of Extrasolar Planets
Microbial Habitability of Icy Worlds
Dynamics of Titan's Troposphere and Formation of Equatorial Dunes
The Influence of Extracellular Polysaccharides on Ions in Sea Ice Brine Pockets (UWAB Research Rotation Presentation)
Rise of the Machines: Mining the Kepler Data for Astrobiology
Research Rotation Talk: From Microbiology to Radiative Transfer: Investigating the Spectral Reflectance of a Cross-section of Microrganisms on Earth and the Possible Implications for Surface Reflectance Biosignatures on other Earth-like Worlds
Topic: Planetary internal processes, magnetism and habitability
Measuring Atmospheric Carbon Dioxide from Space – the NASA Orbiting Carbon Observatory-2 (OCO-2)
Liquid Water on Mars Down to –120°C: Experimental Evidence for Supercooled Brines and Low-Temperature Perchlorate Glasses
Meteorites and Ice - A Cosmic Cocktail
Once More Unto the Evolutionary Breach: Microfossils and the Mesoproterozoic Rise of Complexity
The New Colors of the Red Planet: Reflectance Spectroscopy and the Habitability of Ancient Mars
Organic Geochemistry: From Hydrothermal Vents on Earth to the Great Lakes of Titan
An Early Earth Predisposed to Phosphorylation of Organics
Ammonia Oxidizing Archaea Survival Mechanisms in Low-Nutrient Environments
Making Time for Astrobiology Outreach: How teaching English through Astrobiology in East Africa led to the Astrobiology e-mentoring network, SAGANet.org-- and how you can get involved!
Do Magnetospheres Matter?
Indication of Insensitivity of Planetary Weathering Behavior and Habitable Zone to Surface Land Fraction
A coupled geochemical-bioenergetic model to constrain the potential for methanogenesis in serpentinizing systems
Interrogating the DNA of arsenate-grown GFAJ-1 cells: tools, techniques, and data
The Algorithmic Origins of Life
Modeling the Climate of Exoplanets with GCMs
Influence of Precipitation on the Movement of Salts Through Hyper-Arid Desert Soil
Sixty Minutes to Near-Space: Using High Altitude Ballooks as Inexpensive, Mission-driven Experiences in the Space Sciences
Teaching the Teachers: Integrating Astrobiological Concepts into Secondary Education by Reaching Teachers at the Masters Level
The Meaning of "Life": Astrobiology and Philosophy
The Earliest Aqueous, Habitable(?) Environments on Mars: A View from Orbit
Geochemistry Meets Biochemistry in Hydrothermal Ecosystems
Tales of Habitability: The Curious Case of M Dwarf Planets
The Future of Human Life: Mars, Exoplanets, and the 100-year Starship Project
Exploring Mars for Evidence of Habitable Environments and Life
How the Migration of Jupiter Shaped the Inner Solar System: "The Grand Tack"
The Importance of Tidal Flow in Maintaining an Abundance of Liquid Oceans in the Universe
The Role of Sulfur in Regulating Earth Surface Oxygen Levels
A Self-Assembly Approach to the Proto-RNA World
Subglacial Environments: The Other Deep Biosphere
A Rainbow of Ocean States
The (Sub)glacial Biosphere: Microbial Activity at Zero Degrees Celsius and Below
The Habitability of Icy Moons
Atmospheric Composition and Climate on the Early Earth
High Energy Processing of Phosphorus on the Early Earth
Microbial Mat - Environment Interactions in Lake Joyce, Antarctica, and Implications for Archean Microbialites
The 1953 Miller Experiment and the Origins of Life: The Ghosts Behind the Molecules
Lunar Impact Cataclysm: Implications for Astrobiological Conditions Throughout our Solar System & in Other Planetary Systems
Starshades and Direct Observation of Exoplanets
Where Did Protein Come From?
Efficiency of Photon Energy Use for Life Processes: Implications for Spectral Biosignatures
Joule Heating of the South Polar Terrain on Enceladus
Results from the Mars Phoenix Mission for Mars Habitability and Comparisons to Mars-like places on Earth
The Diversity of Extrasolar Terrestrial Planets
Understanding the Origin of Life
Mars, Venus, and What's Life Got To Do With It
Geobiochemistry and Evolutionary Metallomics: The Evolution of Life and the Biochemical Consequences of Earth History
Mars Subsurface Warming at Low Obliquity: Potential for Periodic Production of Liquid Water
Geomimetic Biochemistry: How the Origin of Biochemistry may be Linked to the Earth's Early Abiotic Organic Landscape
Abiotic Chemistry, Atmospheric Hazes, Titan, and the Early Earth
Quantifying Habitability as Organism/Environment Energy Balance
A Complex Compositional and Aqueous History of Mars
Habitability of Tidally-Locked Terrestrial Exoplanets
Cyanobacteria in a Lunar Environment
Was the Early Earth Hot?
Using Polarization to Detect and Characterize Extrasolar Planets
Earth System Analysis: Applications to Astrobiology
Stromatolites: What's Sulfur Got to Do With It?
Phosphorus and the Origin of Life
Upper Atmosphere Interactions Within the Saturn/Titan System
Exotic Earths: Hot Jupiters, Tidal Evolution, and Ocean Planets
Measuring CO2 From Space: The Orbiting Carbon Observatory (OCO) Mission
Mars: Where Did All The Water Go?
Four Billion Years of Climate Change (Lessons from the Precambrian): From Oxygen Poisoning to Snowballs & True Polar Wander
Left & Right: Geochemical Origins of Life's Homochirality
Gas Hydrates as Planetary-Scale Water and Greenhouse Gas Reservoirs: Implications for Astrobiology
From Carbon Planets to Water Planets: The Composition of Low-Mass Extrasolar Planets
Planets Around Other Stars: Exploring Habitability and Spectral Signatures
Self-Assembly Processes in the Prebiotic Environment
A (Not So) Brief History of Carbon on Earth
1) Very early, Rubey pointed out the drastic geochemical and sedimentological consequences of a large CO2-rich atmosphere, including both severe weathering effects and consequent massive deposition of carbonate rocks, for which there is little or no evidence in the early Archean.
2) The delay in oxygenation of the atmosphere following the advent of oxygenic photosynthesis in cyanobacteria, as early as 2.8 BYBP (perhaps even earlier) is a long recognized (if often ignored) problem. Analysis of various sinks and nutrient constraints does not eliminate this problem.
3) The record of carbon isotopes in sediments points to a longstanding (at least since ca. 3.5 BYBP) balance between carbonate carbon and biogenic (fixed organic) carbon at a ratio of about 4 to 1. This implies substantial (and very early) fixation of large amounts of biogenic carbon and release of proportional amounts of free oxygen, which is inconsistent with geologic and isotopic evidence for an anoxic surface environment until ca. 2.1-2.3 BYBP.
These problems could be solved if one could identify a reservoir to hold the degassed carbon and release it into the biosphere on a geologic time scale. The lack of residual early Archean carbonate sediments (or metasediments) from such a hypothetical reservoir speaks against carbonate as the reservoir substance. The likelihood of early degassing precludes a deeper (e.g. upper mantle) reservoir. The only remaining choice is a reduced carbon reservoir at or near the surface. This reservoir cannot be atmospheric methane (or other gaseous hydrocarbon) because photochemical reactions rapidly remove such compounds from the atmosphere. An early ocean with a high concentration of photochemically (and electrically) produced complex organic compounds solves all of these problems, with the added attraction that it is a favorable environment for the emergence of life. The oxidation of subducted organic rich sediments during upper mantle magmagenesis slowly provides CO2 to the surface environment, on a time scale consistent with the time scale for oxygenation of the surface environment by photosynthetic cyanobacteria, with the record of carbon isotopes in sedimentary rocks, and with the record of carbonate sedimentation. An early reduced carbon reservoir at/near Earth’s surface follows directly from early degassing, under reducing conditions, of the original (and/or hydrogenated) meteoritic carbon compounds. The largely methane atmosphere so produced is short lived, but the photochemical products accumulate in the ocean and are continuously recycled into the atmosphere as methane by low temperature hydrothermal activity. This model provides a suitable source of the early (methane) enhanced greenhouse effect.
Cosmology and Life
The Future of Extrasolar Planet Searches
Life in Igneous Rocks on Earth and Mars
Life in Igneous Rocks on Earth and Mars
The Ring of Life Provides Evidence for a Genome Fusion Origin of Eukaryotes
Life Below and Life "Out There": The Role of Caves in Astrobiology
The Mars Exploration Rover Mission
The Suboxic Zone in the Black Sea
In the Rearview Mirror: Studying the Role of Comets in the Formation and Ongoing Evolution of a Planetary System
Why There Were Dinosaurs; Why There Are Birds
Methane Greenhouses and Anti-Greenhouses on the Early Earth
The Transition from Anoxygenic to Oxygenic Photosynthesis and How It Changed the Earth
A Subsurface Biota in the Archean?
Energetic Habitability: Boundary Conditions for Life-As-We-Know-It
Microbial Biosedimentology of Some Extreme Terrestrial Environments with Implications for the Exploration for Extraterrestrial Life
Geochemical Seasonality in a Unique Aquatic Environment: Who Needs Oxygen, Anyway?