2019 Fiscal Year Annual Research Report

The formation and evolution of Mars: Composition and early surface environment

Research Project

Project/Area Number	19J13927
Research Institution	Tokyo Institute of Technology
Principal Investigator	WOO Man Yin 東京工業大学, 理学院, 特別研究員(DC2)
Project Period (FY)	2019-04-25 – 2020-03-31
Keywords	Mars / isotope / giant impact / planet formation / SPH / N-body
Outline of Annual Research Achievements	I published two papers during my PhD study. The first paper is about combining isotopic data from meteoritic study and N-body simulation results to further constrain planet formation models. Our team found that in order to reproduce the isotopic differences between Earth and Mars, a compositional change of the initial solid disk from enstatite chondrite to ordinary chondrite have to occur at around 1.3 AU from the Sun, regardless of the dynamical models we adopted for the N-body simulations. This study opens the door of combining meteoritic studies with computational simulation data to study planet formation. My second paper focuses on dictating the early surface environment on Mars after a single giant impact. Our team combined Smooth particle hydrodynamic (SPH) simulations with analytical theory to calculate whether a giant impact between a Ceres-sized impact and the early Mars is sufficient in changing the early surface environment on Mars. Such giant impact is likely to have occurred no later than 4480 Ma. We found that after the giant impact, about 3 bars of hydrogen (H2) gas is formed. A thick H2 atmosphere could be an important source for triggering life on a planet since it maintains a reducing environment which favorite pre-biotic chemistry. However, such thick H2 atmosphere is unlikely to survive more than 20 Myr, due to the active young Sun. Hence we concluded that it is difficult for life to emerge on Mars after this late giant impact. This is an indicative research on the possibility of searching for extraterrestrial life on Mars.
Research Progress Status	令和元年度が最終年度であるため、記入しない。
Strategy for Future Research Activity	令和元年度が最終年度であるため、記入しない。