Welcome to the 2017 Spring Astrobiology Colloquium Series!
We have an exciting line-up for the Spring! From biosignatures and planetary analogs to icy worlds and Proxima Cen b!
Do Microbe-Mineral Interactions Produce "Biosignatures"?
by Aude Picard (Dept. of Organismic and Evolutionary Biology, Harvard University)
On Earth, atmospheric oxygen played a significant role in the evolution of complex life. Oxygen levels in the atmosphere are controlled over geological time scales by the burial of iron sulfide minerals and organic carbon in sediments. Microorganisms drive the redox transformations of Fe, S and C from the surface of the Earth down to the depths of the continental and oceanic crusts. Due to their metabolic capabilities, as well as to their surface properties, microorganisms can mediate the precipitation – and influence the morphology and composition – of a variety of minerals. For this talk, I will present experimental work demonstrating the role of sulfate-reducing microorganisms in producing iron sulfide minerals with unique physical characteristics and composition. I will then discuss the potential for microbe-iron sulfide mineral interactions to be used as “biosignatures” for the presence of microbial life in ancient anoxic environments on Earth or elsewhere.
Thinking Alien Abysses: How High-Pressure Experimental Thermodynamics of Aqueous Systems Help Us Constrain the Structure and Habitability of Deep Planetary Hydrospheres
by Olivier Bollengier & Baptiste Journaux (Earth and Space Sciences, UW)
The possible presence of deep aqueous salty oceans in icy moons (Europa, Ganymede, Titan, etc.), and potentially in water-rich exoplanets, has generated a lot of enthusiasm in the astrobiology community and is one of the focus of future NASA and ESA missions (Europa Clipper and JUICE, respectively). However, as the pressure, temperature and chemistry expected to characterize these oceans lie beyond those encountered in Earth’s natural environments, our understanding of these alien places remains hindered by a historical lack of experimental and theoretical constraints of aqueous systems at these specific conditions. Pressure, temperature and chemistry induce important changes to the physical properties of fluids and ices (e.g. density, crystallographic structure), to the extent that structural models of icy worlds can not rely solely on extrapolated properties of pure water. We will present current experiments and models from our team at the ESS-UW and highlight potential effects of these altered properties on the structure and habitability of large icy worlds.
Missions to Planetary Analogs: Science and Technology that Enable Robotic Planetary Exploration
by Pablo Sobrón (SETI Institute)
Studies of different, extreme environments on Earth have revolutionized our understanding of how life on Earth might have emerged, and also have advanced our knowledge of possible environments where life could exist on other planets. To advance this knowledge further and to prepare for the exploration of potential habitable environments elsewhere, there is a need for new, innovative in-situ exploration technologies and analytical methods. In this talk I will review our most recent field campaigns to planetary analog environments, from desert to Antarctic settings, where we have tested and refined new technologies and operational strategies for the in-situ astrobiological exploration of Mars, Europa, and beyond.
Discovery of Proxima Centauri b
by Guillem Anglada-Escudé
by Ariel Anbar (Arizona State University)
by Sheri B. Wells-Jensen (Bowling Green State University)
The Promise of Polarimetry for Biosignatures and Habitability Markers
by Kim Bott (Astronomy, University of Washington)
The practical utility of polarimetry in determining cloud species, identifying biomarkers, and detecting ocean glint is assessed with a first order example in the form of the Earth as an exoplanet. Polarimetric surface mapping can provide detailed information about terrestrial exoplanets which may be crucial to exotic worlds such as super Earths and planets around red dwarfs. We explore the capabilities of polarimetry in the context of state-of-the-art Earth-based imaging and aperture polarimeters (e.g. SPHERE or HiPPI) and next era space telescopes (e.g. HabEx or LUVOIR). This research is relevant to upcoming large ground-based and future NASA exoplanet characterization missions, such as the proposed HabEx and LUVOIR telescope concepts.
The Climate of Archaean Earth Under a Thin Atmosphere
by Rodrigo Luger (Astronomy, University of Washington)
Recent studies have suggested that Earth's atmospheric pressure during the Archaean may have been significantly lower than today. This fact appears to be at odds with the well accepted notion that the Earth maintained habitable surface temperatures during the Archaean, since under a fainter Sun and a thinner atmosphere the Earth would have been far more susceptible to runaway glaciation. We report on preliminary results showing how changes to the dynamics of Hadley circulation under a thinner atmosphere may have kept the majority of Earth's surface habitable 3-4 Gyr ago.
Geophysical Constraints on the Habitability of Icy Ocean Worlds
by Steve Vance (JPL)
Earth's habitability depends on its interior structure and dynamics. Similarly, the habitability of ocean worlds must be understood in terms of their interior structures and evolution. Combined seismology, gravity, and magnetic investigations can constrain the radial structure and configuration of the ices, oceans, rocky interiors, and metallic cores. They may also be able to infer ocean composition and constrain the extent of water-rock alteration in the rocky interior. However, this requires understanding possible degeneracies of those geophysical measurements in the continuum of possible compositions. Here we present self-consistent 1-D structural forward models that predict interior density, temperature, sound speed, and estimated electrical conductivity. The models are limited by the availability of thermodynamic data, including suitable properties of ices at low temperatures; insufficient coverage in pressure, temperature, and composition for end-member salinities of MgSO4 and NaCl; and no suitable data for aqueous mixtures of Na-Mg-Cl-SO4-NH3. While models for Europa illustrate these problems for high concentrations of NaCl modeled as seawater, they also show the potential for unique signatures of ocean temperature, density, sound speeds, and electrical conductivity. Titan's gravity field requires a salty ocean that may eliminate or drastically reduce the presence of high pressure ices. Enceladus has a highly porous interior consistent with extensive fluid-rock interaction. Ganymede has the deepest silicate layer, with pressures at the its water-rock interface approaching 16,000 atmospheres. Callisto's internal structure is less constrained, but its silicate depth is intermediate to those of Ganymede and Europa, and its geology suggests a nearly-frozen eutectic, implying the presence of buoyant high-pressure ices.
Missed the last seminar series? See our archive for abstracts and video recordings of all past talks from 2003 - Present.