COLLEGE OF SCIENCES

SCHOOL OF EARTH AND ATMOSPHERIC SCIENCES

EAS Ph.D. Defense

George McDonald

July 11, 2018

11:30 PM

Earth and Atmospheric Sciences

Ford Environmental Science & Technology (ES&T)311 Ferst Drive, ES&TAtlanta, GA 30332-0340Web: eas.gatech.edu

ES&T

L1114

Title: The impacts of atmospheric radiation on studies of planetary habitability

Committee members: Dr. Simon, Dr. Wray, Dr. Sokolik, Dr. Steffes(ECE), Dr. Lopez (NASA)

Announcement Abstract: Announcement Abstract: The conditions required for Earth-like life to emerge on a planetary body are thought to include the presence of liquid water, the availability of energy and the existence of organic material. There are situations when determining whether the above conditions exist on a planetary body is not possible without a detailed understanding of the radiative processes occurring in a planet's atmosphere. In this work, studies of the radiative flux and transfer within planetary atmospheres are carried out in order to elucidate whether certain planetary bodies may be habitable. The first section of this work quantifies the impinging X-ray flux on sub-Neptune sized planets in the Kepler spacecraft dataset to determine the conditions for such planets to be stripped of their primordial atmospheres, with implications for the stability of liquid water on their surfaces. In the second part, the absorption of light in the atmosphere of Saturn's largest moon Titan due to methane and other gases is modeled in order to understand how close to the surface one has to be to detect organic molecules of prebiotic relevance, including amino acids and nucleobases.