University of Washington Seminars Seminars University of Washington seminar series is hosted by the NAI Virtual Planetary Lab (VPL) team live from the University of Washington campus in Seattle. Seminarsen-usSat, 06 Jun 2020 05:18:33 +0000Getting Under Europa’s Skin is one of the most enticing targets in the search for life beyond Earth. With an icy outer shell hiding a global ocean, Europa exists in a dynamic environment where immense tides from Jupiter potentially power an active deeper interior and intense radiation and impacts bathe the top of the ice, providing sources of energy that could sustain a biosphere. Europa’s icy plate tectonics, and evidence for shallow water within the ice, implies that rapid ice shell recycling could create a conveyor belt between the ice and ocean, allowing ocean material to one day be detected by spacecraft. Beneath ice shelves on Earth, processes such as accretion, melt and circulation mediate the ice as an important element of the climate system. Here, ice-ocean exchange may be similar to that on Europa, but is difficult to observe given the harsh environment and thickness of the ice. Thus exploring the cryosphere can form the foundation of our understanding of other ocean worlds and a test bed for their exploration. In this presentation, we will explore environments on Europa and their analogs here on Earth. NASA will launch the Europa Clipper Mission in 2021, but while we wait to get there, we are looking to our own cosmic backyard to help us to better understand this enigmatic moon. I will describe our work on the McMurdo and Ross Ice Shelves under our 2017-2020 field program, RISE UP, using the under ice AUV/ROV Icefin built by our lab. We will also describe our work in collaboration with the University of Otago and Antarctica New Zealand on the Ross Ice Shelf Programme, and with the NERC-NSF International Thwaites Glacier Collaboration. Using this new robotic capability, we are working to gather unique new data relevant to climate and planetary science, and develop techniques for together exploring the Earth and one day Europa, an ice-covered world not so unlike our own. Formation and Evolution of Outer Solar System Bodies Through Stable Isotopes and Noble Gas Abundances of 14 N/ 15 N in HCN and N 2 in the atmosphere of Titan provides direct evidence of how photochemistry influences stable isotopes. We have used these observations to determine that Titan’s nitrogen originated as NH 3 in the protosolar nebula. All of this work relies on spacecraft-based observations made at Titan. Ground-based observations combined with spacecraft observations are also of high value. The lower limit observed for 14 N/ 15 N in HCN in Pluto’s atmosphere by ALMA combined with New Horizons observations of the atmospheric composition provides a valuable tool for determining the origin of nitrogen for Pluto if the influences of condensation and aerosol trapping on isotopes can be constrained for which work is ongoing. All of this work is relevant to a future Ice Giants mission to Neptune, where the same methods could be applied to Triton and combined with ALMA observations. Furthermore, a mission to Io that makes in situ observations of the isotopic composition of the atmosphere could provide important information about volatile loss and interior processes at Io, assuming production and loss processes can be well constrained. Finally, noble gas abundances have been an important tool for understanding the origin and evolution of volatiles in the terrestrial planet atmospheres. The recent measurement of cometary noble gas abundances provides important information on the composition of the icy bodies that contributed to the formation of the gas giants, providing constraints for future in situ measurements that should be made with an atmospheric probe., a Planetary Revolution is the most important bioenergetic innovation in the history of the biosphere and it engendered Earth’s most marked environmental change: the rise of dioxygen. Photosynthesis dramatically increased global primary production and transformed Earth's chemical cycles. At the same time, this new photosynthetic source of oxygen brought about tremendous biological change. Oxygen rewrote life’s recipe book, facilitating evolution of the richness we associate with modern biology. In this talk I will present observations from a range of perspectives including genomes, chemistry, and the ancient sedimentary rock record to illustrate what we can learn about how this process emerged two-and-a-half billion years ago—drawing specifically on the special role of the element manganese in this history. King of the Gases is the heaviest gas in the atmosphere, yet it is also, next to helium, the gas for which there is the greatest evidence of escape to space. Trapped gases in old rocks indicate that Xe escape occurred throughout the first half of Earth's history. Here we discuss how Xe can preferentially escape from Earth as an ion, which maps to constraints on the hydrogen abundance in Earth's ancient atmosphere. We find that hydrogen (or methane) mixing ratios must have exceeded 1% for Xe to escape. We conclude that hydrogen (or methane) was a major gas in Earth's atmosphere at times through the first half of Earth's history --- although not persistently --- and that Earth probably lost the hydrogen from an ocean of water before embarking on the Neoproterozoic 2.4 billion years ago. Molecules Matter: Phosphorus and Its Sources on the Early Earth earth scientists usually view phosphorus as being synonymous with phosphate, with the two terms often being interchangeable. Instead, the ion phosphite may have been more important on the early earth, especially with respect to being a phosphorus source for developing life. Recently, several sources of phosphite have been identified, including lightning, meteoritic corrosion, diagenesis of iron-bearing sediments, and serpentinites. As the phosphite ion is notably more soluble than phosphate, it may have controlled early P availability on the earth. A geochemical justification for phosphite is reviewed in this talk. Exoplanetary Atmospheres With JWST: Insights From Solar System Science will soon have the technological capability to measure the atmospheric composition of temperate Earth-sized planets orbiting nearby stars. Interpreting these atmospheric signals poses a new challenge to planetary science. In order to understand the degree to which we will learn of terrestrial planets from their atmospheres, I use the mystery of early Mars as a case study. I describe how we leverage models to learn of Mars’ ancient past, and make the case that this will be a very similar problem to the characterization of terrestrial planets with JWST. Then, I lay the framework for an information content-based approach to optimize our observations and maximize the retrievable information from exo-atmospheres. First I test the method on observing strategies of the well-studied, low-mean-molecular weight atmospheres of warm-Neptunes and hot Jupiters. Upon verifying the methodology, I finally address optimal observing strategies for temperate, high-mean-molecular weight atmospheres (Earths/super-Earths) and discuss what we can hope to learn from terrestrial exoplanets. Exoplanet Atmospheric Loss by Observing Isotopologue Bands With the James Webb Space Telescope planets orbiting M dwarfs may soon be observed with the James Webb Space Telescope (JWST) to characterize their atmospheric composition and search for signs of habitability or life. These planets may undergo significant atmospheric and ocean loss due to their host stars superluminous pre-main-sequence phase, which may leave behind abiotically-generated oxygen, a false positive for the detection of life. Determining if ocean loss has occurred will help assess potential habitability and whether or not any O2 detected is biogenic. In the Solar System, differences in isotopic abundances have been used to infer the history of ocean loss and atmospheric escape (e.g. Venus, Mars). I will show how H2O and CO2 isotopologue measurements using transit transmission spectra of terrestrial planets around late-type M dwarfs like TRAPPIST-1 are possible with JWST, if the escape mechanisms and resulting isotopic fractionation are as severe as Venus, and could be considered as indicators of ocean loss and atmospheric escape, as they have in our Solar System. Phototrophy: Crazy? You Tell Me is quintessentially a disequilibrium process. In other words, the dissipation of free energy underpins life’s ability to perform the myriad other functions that we ascribe to the living state—homeostasis, autocatalysis, order, complexity, information storage, replication, learning, etc. The pathways that begin with the liberation of free energy and culminate in biological order are captured in the various metabolisms of life on Earth. However, it is far from guaranteed that life on Earth encompasses all possible ways that an organometallic system in aqueous solution can harness free energy to self-assemble, grow, and replicate. Here, we envision a new pathway called “inverse phototrophy,” in which life utilizes sunlight in an oxidant-starved environment to produce an in-house electron acceptor for metabolism. Acid Membranes, Peptide Production, and the Origin of Life life on Earth consists of protein and nucleic acid biopolymers encapsulated by a semi-permeable membrane. Any reasonable theory for the origin of cells must explain the formation of the two types of macromolecule, as well as their co-localization within a membrane bounded space. Here I describe a membrane-centric theory for the origin of cellular life, where prebiotic fatty acid molecules self-assemble into a bilayer membrane, this membrane binds amino acids, and eventually helps catalyze their polymerization into peptides. I will explain how extant life informs us of possible prebiotically relevant peptide precursors, and how membranes could promote and isolate polymerization reactions. Archean pCO2 With Micrometeorites talk is the culmination of my research rotation with Don Brownlee (UW Astronomy department) and Roger Buick (UW Earth and Space Sciences department). The goal of this project was to find iron micrometeorites in Archean sedimentary rocks and analyze their composition. Metallic micrometeorites melt when entering Earth’s atmosphere and Archean samples could provide a record of the Archean upper atmosphere, in which they were molten and readily reacted with the surrounding gases. This talk will focus on the lab techniques I learned and used to look for micrometeorites as well as the modeling effort needed to constrain atmospheric composition based on the micrometeorite measurements.