Fall 2015

An Update from our Students

By Giada Arney
Student Representative, UW Astrobiology Steering Group

2015 marked the 25th anniversary of the Voyager "Pale Blue Dot" image made famous by Carl Sagan. Fittingly, many exciting events related to astrobiology happened this year. On Mars, NASA recently announced the discovery of concentrated salty water in recurring slope lineae (seasonal flows on sloped surfaces). Farther away, New Horizons whizzed by Pluto in July and took the first ever close-up photos of this distant dwarf planet. Pluto may be similar in composition to the cometary material that supplied some of Earth's water inventory, and New Horizons has shown us that this tiny world is truly amazing and surprising. Even farther out, the number of known exoplanets is now at 1600, while the number of planetary candidates numbers at 3700! To think that just twenty-odd years ago, we only knew of the planets in our solar system...! Our astrobiology workshop this year was at Yellowstone National Park, and the students who attended had an amazing time analyzing the extreme microbes that inhabit the colorful hydrothermal pools (check out the workshop writeup via the link on the homepage!). UW astrobiology students are at the forefront of advancing our knowledge of Earth and its biosphere, worlds across our solar system, and distant exoplanets.  Here are some of the exciting projects we are tackling right now.

Untangling the Web of Earth's Biosphere

To understand life elsewhere, we must start with life on Earth. Anna Simpson recently collected sediments from beneath the snowpack on the Muir Snowfields in Washington state in areas that may have been exposed to the surface for the first time in decades. She is looking for differences in the microbial community with ice and snowmelt.  Osazonamen (Osa) Igbinosun spent the summer quarter screening plant growth in planetary (Mars/Lunar) simulant soils inoculated with willow and poplar endophytes for her research rotation project. Results suggest that crop plants such as broccoli and tomatoes perform well in Mars soils (unfortunately, potatoes were not used in this study!). Matt Koehler is on his research rotation at St. Andrews University in Scotland working with former UWAB alum Mark Claire and is conducting microbiology experiments to determine how bacteria that use hydrogen sulfide and elemental sulfur turn oceanic nitrate into nitrogen gas. Jon Zaloumis is a first year graduate student interested in characterizing early life via chemical signatures in the rock record. He will be working with Professor Roger Buick on trace metal and stable isotope signatures of life in 3.5 billion year sedimentary rocks from the Pilbara region of Western Australia. Jaclyn Saunders is researching bioinformatic approaches to investigate arsenic-based metabolisms in global oxygen minimum ozones, which are excellent proxies of ancient anoxic oceans. Robert Tournay has been isolating and characterizing non-pathogenic bacteria colonizing the internal tissues of plants growing on metal-rich soils to investigate the role of the plant microbiome in conveying host-plant tolerance to soil heavy metals. The short generational timescales and proclivity for sharing genetic information between species means these mutalistic bacteria could act as a mechanism of rapid host plant adaption when colonizing novel habitats. Chloe Hart is finishing her AB research rotation with John Leigh (microbiology), focused on isolating marine microorganisms that participate in synthrophic interaction. These organisms require each other's presence to break down complex organics and ultimately produce methane. Gordon (Max) Showalter is researching bacterial motility in low temperatures for use as a potential biosignature in extreme environments, including the Arctic or Icy Moons. 

The Next Best Thing to a Time Machine: Earth's Current and Past Environments

As our (so far!) one example of existing life in the universe, Ancient Earth is a natural laboratory for studying how life arose and evoloved. Michael Kipp is using geochemical proxies to study the evolution of Earth's atmosphere across the Proterozoic Eon (2.5-0.54 billion years ago) and is conducting microbial experiments to develop new proxies for gauging greenhouse fluxes in this time period. Paul Kitner has been working to create complex high power cartridge heaters to understand the habitability of Lake Vostok in Antarctica using radioglaciological techniques. Giada Arney is using computer simulations constrained by geochemical evidence to examine haze formation in the Archean (4-2.5 billion years) and understand how these hazes would impacted early Earth's climate and acted as a UV shield before the rise of the ozone layer. Matt Koehler is exploring nitrogen cycles in the Neoarchean (about 2.7 billion years ago) and Mesoproterozoic (1.4-1.6 billion years ago), trying to figure out how Earth's oxygenation through time may have affected the availability of nitrogen to microbial life. This is important because all life as we know it requires nitrogen. Jaclyn Saunders will be completing a research rotation this fall looking at arsenic abundances in the geological record. Aaron Brewer is developing a method for analyzing potassium isotopes to be applied to a variety of geochemical and cosmochemical processes.

Our Neighborhood, the Solar System

UW astrobiologists continue to excel in developing our understanding of potential habitats elsewhere in the solar system. Matt Tilley continues to study the effects of variable plasma pressures in Saturn's magnetosphere to see they might affect Titan's habitability and atmospheric evolution. Michael Diamond is studying cloud-aerosol impacts on planetary climates and whether it is possible to detect microbes that could be ejected from water plumes on Saturn's moon Enceladus. First year grad student Owen Lehmer is interested in modeling the atmospheric evolution of the moons of Jupiter. Steven Sholes is modeling the Martian atmosphere to show how volcanic gas emissions in the past may have created a more habitable atmosphere. Joshua Krissansen-Totton has been studying chemical disequilibria in planetary atmospheres as a potential biosignature in the context of varied solar system worlds and exoplanets. Elena Amador is using satellite imagery of the Martian surface to identify areas that once may have been altered by water in the distant past. 

Pale Blue (And Other Colored) Dots: Distant Exoplanets

UW graduate students are at the forefront of developing techniques to model and characterize distant planets and planetary systems. Matt Tilley is studying stellar flare effects on the habitability of planets orbiting low-mass "M dwarf" stars by examining the impact of ion chemistry and atmospheric energy deposition on Saturn's moon Titan. Jacob Lustig-Yaeger is developing a suite of tools to measure the composition of an exoplanet's atmosphere given the limited data we will have from the first direct exoplanet observations of habitable planets. Nichole Barry is researching the 21 centimeter hydrogen hyperfine transition as a signal of the epoch of reionization, when the first stars turned on. She hopes to translate her radio data analysis techniques to an astrobiological context through study of exoplanet magnetic fields or ice rings. Brett Morris is investigating the use of transiting exoplanets to study their host star's stellar activity level. Russell Deitrick is studying orbital and rotational dynamics of exoplanets and the resulting impacts on climate. He is working to incorporate these processes into a larger model that couples many physical processes to understand the habitable zone in a comprehensive, integrated context. Rodrigo Luger is investigating the habitability of planets around stars less massive than the Sun, focusing on their atmospheric evolution and on the stability of their surface water. He is also analyzing populations of Kepler planets to constrain tidal evolution in exoplanet systems. Eddie Schwieterman published a paper studying nonphotosynthetic pigments as surface biosignatures on exoplanets. He also recently published a paper quantifying the detectability of nitrogen gas in exoplanet atmospheres.  Giada Arney is studying how hazes form around planets orbiting varied types of stars and whether these hazes can serve as non-gaeous atmospheric biosignatures. Steven Sholes, Joshua Krissansen-Totton, Matt Koheler and former UWAB graduate student Amit Misra collaborated on a project that investigated the detection of volcanism on exoplanets. Andrew Lincowski has begun investigating the effect of carbon dioxide ice clouds on the outer edge of the habitable zone; previous work has assumed these clouds would warm their planets, but more recent studies suggest their net effect would actually be cooling. Diana Windemuth is working to create a pipeline to search for transiting circumbinary planets (i.e. planets orbiting two stars at once) in the Kepler eclipsing binary catalog. Joshua Krissansen-Totton has been investigating whether planet color could be used to identify potentially Earth-like exoplanets.

Education and Public Outreach

At UW, we know that engaging with the public, communicating our work, and educating the community is an important part of astrobiology and science in general. Marshall Styczinski studies the impact of online homework and simulations in introductory science classes. Matt Tilley is a Pacific Science Center fellow and is presenting a Science Cafe in Kirkland on November 17. Brett Morris is an organizer of the wildly popular public talk series Astronomy on Tap. Russell Deitrick has been a presenter at Astronomy on Tap, and Eddie Schwieterman is presenting there later in October. Anna Simpson attended a science communication workshop series at the Pacific Science Center this summer and she has been answering online questions submitted to the Center by children about "gross" topics.  Steven Sholes did a "What is Life?" activity with elementary school students at Lister Elementary in Tacoma. In March, he helped teach a Mars/Rover identifying powders lab experiment to third graders at Cougar Ridge in Bellevue. Eddie Schwieterman and Giada Arney participated in the science communication competition "FameLab" last summer in Chicago. On campus, Giada Arney, Eddie Schwieterman, Diana Windemuth, Brett Morris, and Russell Deitrick have given planetarium shows to many K-12 groups to help inspire the next generation of scientists. These five students are also involved with the astronomy department's Pre-MAP program, which helps entering students gain research experiment their first quarter at UW.

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