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Astrobiology Autumn Colloquium Series - Max Showalter (University of Washington, Oceanography) and Andrew Lincowski (University of Washington, Astronomy)
WhenTuesday, Oct 29, 2019, 3 – 4 p.m.
Campus locationPhysics / Astronomy Auditorium (PAA)
Campus roomPAA 102
Event typesLectures/Seminars
Target AudienceUWAB Community including General Public

Modeling Virus-Host Dynamics in Ice

Bacteriophage, viruses which infect bacteria, are important drivers of biogeochemical cycling in marine environments, “short-circuiting” the microbial loop in a process known as the viral shunt. It has been observed that bacteriophage are especially concentrated in sea ice and therefore may play a similar role in sea ice brine ecosystems - on Earth, or on icy moons like Europa. However, the existence and potential importance of a viral shunt within sea ice remains understudied. I will present results from my summer rotation at the University of Tennessee, Knoxville, where I sought to develop a mathematical model to evaluate the existence of a viral shunt within sea ice and estimate its impacts on biogeochemical cycling. This model, constrained by field observations and laboratory studies of sea ice isolate systems, can then be used to extrapolate habitability of analogous environments on icy moons such as Europa and Enceladus.

The Carbon Cycle for Ocean Worlds

Ocean-covered planets may represent the best path to habitability for the types of small planets that may be observed with the James Webb Space Telescope (JWST). The TRAPPIST-1 system, hosting seven terrestrial-sized planets in and around the star’s liquid water habitable zone, is currently the best target for JWST to probe the atmosphere of a temperate planet. The slightly low planet densities suggest they may have a higher fraction of water than Earth, and so may be completely ocean-covered. From Earth, it is typically invoked that the buffering feedback for CO2 (and hence, climate) is the carbonate-silicate cycle, and that this cycle requires exposed land near water bodies to function. Recently, a mechanism called “reverse weathering” has been introduced, which may enhance the equilibrium CO2 in the atmosphere-ocean system. Here we include reverse weathering in a global carbon model to explore the potential habitability of ocean worlds that may exist in the TRAPPIST-1 and other exoplanetary systems.…
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