2009 Annual Science Report
Pennsylvania State University Reporting | JUL 2008 – AUG 2009
Biosignatures in Extraterrestrial Settings
This project looks at the evolution of the composition of gases in the cold disk from which planets form; the evolution of the atmosphere after planet formation, in particular, the role of trace gases in the early greenhouse effect; and, some aspects of the the formation and later dynamical evolution of extrasolar planets.
4.1.1 We have made significant progress on this work: a paper on the NO2 warming mechanism was submitted . The reviewers made some valid technical comments, which we are now addressing and they advised us to split it into two or three papers.
Recently, we have been concentrating on the SO2 mechanism: 1) We derived thermal-IR absorption coefficients for SO2; 2) photochemical model that can predict the concentrations of sulfate and sulfur aerosols as a function of atmospheric SO2 concentration; 3) derived Mie scattering parameters for sulfate and S8 aerosols and included them in our photochemical and climate models; 4) series of calculations of surface temperature as a function of CO2 partial pressure and SO2 outgassing rate.
4.1.2. Magmatism on young terrestrial planets
Ohmoto presented a paper at the Goldschmidt Conference, suggesting that the volcanic and hydrothermal inputs from the mantle to the atmosphere on early Earth and Mars were dominated by CH4, and that the early life utilized CH4, rather than CO2.
4.2 A collaborative assessment of CO self-shielding in the solar nebula and the presolar molecular cloud showed that 3 environments are viable locations for producing oxygen isotope fractionation consistent with the CAI mixing line. N2 self-shielding can be a source of large 15N enrichment. Critically revisited controversial reports on CO photolysis.
4.3 Graduate student K. Moody, partially supported by PSARC, successfully defended his PhD thesis, including significant work on dynamics of planetary systems. Graduate student Amanda Martin, partially supported by PSARC, submitted a master’s thesis on protoplanetary-like disks around nearby brown dwarfs.
PROJECT INVESTIGATORS:James Kasting
Project InvestigatorJames Lyons
Project InvestigatorHiroshi Ohmoto
Project InvestigatorSteinn Sigurdsson
PROJECT MEMBERS:Mark Claire
RELATED OBJECTIVES:Objective 1.1
Formation and evolution of habitable planets.
Indirect and direct astronomical observations of extrasolar habitable planets.
Earth's early biosphere.