Project Report

This project was completed at the University of Tokyo in the summer of 2011 as part of the East Asia and Pacific Summer Institute. Weaddressed two large questions concerning Titan's atmosphere; how does the atmosphere contain so much methane given its destruction time in the atmosphere of ~30 Mys, and are there different stable configurations (i.e. different amounts of methane and aerosol haze) for Titan's atmosphere with the current volatile inventory. To address these questions, we used a mix of laboratory results and numerical modeling. We created Titan "tholin" analogues in the lab at methane/nitrogen ratios of 0.02 - 0.1. Tholins is greek for mud, and is the condensate that accumulates in the test tubes when combining these gasses and a high energy source, such as a cold plasma, like we used. We found that the tholin production is nonlinear with methane concentration and peaks at about 6% methane. The optical properties, absorption and scattering, of the tholins is also affected by the methane concentration used. We use a numerical model to understand the climatic implications of our lab results. We use a greenhouse/antigreenhouse climate model to calculate the surface temperature on Titan given the atmospheric components and haze properties. We find that under Titan's current conditions and with best estimates of current methane abundance in the atmosphere and lakes, Titan can have multiple stable states. A cool hazy state that Titan is currently in, and a warm haze free state. Since Titan is currently in the cool state, we can put constraints on the amount and time since the last methane outgassing event. No more than about twice the current methane could have been released in the last outgassing event without causing Titan to fall into the warm haze free state. The results of this project have been shared with the academic and public audiences in many ways. This work is submitted to a peer reviewed journal. The preliminary results of this have been presented at two conferences. Presentations have also been given to a wider academic and public audience at the University of Colorado. Finally, this opportunity provided the participants a unique opportunity to do fundamental science in an international setting and form important cross cultural collaborations.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Larson Erik J
United States
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