The Living, Breathing Planet
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Hampton University Department of Atmospheric and Planetary Sciences has been selected to lead a team within the Nexus for Exoplanet Systems Science (NExSS). As one of 17 teams, we work to advance NASA’s search for life by bringing together Planetary Science, Heliophysics, Astrophysics, and Astrobiology to deepen our understanding of what makes planets habitable and habitats detectable.
The specific goals of The Living, Breathing Planet team are to understand how planets and particularly their atmospheres evolve over time through interactions with the space environment and parent star. Our team consists of researchers and students from Hampton University, the University of Maryland, College Park, the University of Virginia, Virginia Tech, NASA Goddard Space Flight Center, the Harvard-Smithsonian Center for Astrophysics, the National Institute of Aerospace, and Science Systems and Applications, Inc.
The concept of habitability is central to the discipline of Astrobiology. Searching for, identifying, characterizing, and even defining the term has been a primary task of the Institute’s first decades, and will continue to be an important effort underlying the work of the next decade. As our ability to find and characterize extrasolar planets continues to strengthen, so will our need to refine our understanding of habitability and the processes that establish and destroy potential habitats.
The atmosphere has long been recognized as being deeply woven into the web of reactions and exchanges that support life on Earth. Through the generic metabolic process of extracting energy from chemical bonds, complex molecules are broken into smaller, more volatile molecules. Many of these metabolic products will be gases that escape into the atmosphere, a feature that affords life an easy way to disperse waste. We can expect this to be true of life elsewhere, and thus our search for such life on other planets naturally begins by interrogating the atmosphere. The Living, Breathing Planet team proposes to undertake a multidisciplinary investigation into the ways in which the space and stellar environment influence the evolution of planetary atmospheres and the detectability of habitable planets. Specifically, we propose to conduct a detailed investigation into a fundamental mechanism of planetary atmospheric evolution — the irreversible loss of light constituents to space.
Hydrogen escape has long been known to have significant effects on planetary chemistry over geologic time. Both Mars and Venus display the effects of hydrogen loss in their elevated deuterium-hydrogen (D/H) ratios, dry surfaces and atmospheres, and oxidized chemistry. The relevance of atmospheric evolution by hydrogen escape for the assessment of habitability was sharply driven home in 1976 by the results of the Viking lander biology experiments which were confounded by the highly oxidized Martian soil. The importance of hydrogen and water for habitability mean that future attempts to find life by analysis of planetary atmospheres must account for atmospheric evolution driven by escape.
The Living, Breathing Planet team’s investigation will reach across vast distances using data collected from telescopic and spacecraft investigations of the planets orbiting our Sun and other stars. We will integrate geochemical, atmospheric sampling, remote sensing and telescopic observations with detailed physical models to investigate the processes that link the destiny of a planet’s atmosphere with the dynamics of its host star and space environment in order to test fundamental hypotheses about what makes a planet habitable and how habitability can be reliably identified.