Member

SUGITA, Seiji

Associate Professor
Graduate School of Frontier Sciences

Office: Kashiwa, Kiban-4H4
TEL: +81-4-7136-5520
FAX: +81-4-7136-3953
E-mail:
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Research Field

Planetary Science, Astrobiology

Current Research

The goal of my research is to understand the current conditions and histories of both planets and satellites in the Solar System through studying hypervelocity impacts and craters. I take three different approaches to achieve this goal. First, hypervelocity impact phenomena are studied using laboratory experiments. The main observational method is emission spectroscopy. I have developed spectroscopic techniques to determine various thermodynamic quantities of impact vapor clouds, such as temperature, density, and chemical composition. Using this technique, I am investigating both energy-partitioning mechanisms from impactors to vapor clouds and chemical reactions within vapor clouds. The energy-partitioning mechanisms determine the size and temperature of impact vapor clouds, and hence the magnitude of their effects on planetary geology. Chemical reactions within vapor clouds are expected to be important for production of prebiotic organic matter on both Earth and Mars in their early histories.
The second approach is planetary missions. I have participated in studying a science definition for Japanese lunar mission, SELENE, particularly for selenodesic measurement programs: RSAT and RISE. I am assessing the effects of rheological properties of the lunar interior on impact craters and basins. Such knowledge will help interpreting selenodesic data and understanding the thermal history of the Moon.
The third approach is numerical calculations. This is complimentary to the above two approaches and used simultaneously with them. I have developed 1- and 2-dimenstional hydrocodes capable of calculating extremely intense shock waves. Using these codes, I am assessing fluid dynamic behavior of impact vapor clouds both observed in laboratories and inferred in the Venus atmosphere. Such calculations are useful for interpreting both experimental data from laboratories and planetary data from on-board instruments.

Representative Publications

1. Sugita, S. et al., Subaru Telescope Observations of Deep Impact, Science, 310, 274-278, 2005.
2. Sugita, S. and P. H. Schultz, Interaction between Impact-Induced Vapor Clouds and the Ambient Atmosphere 2: Theoretical modeling, J. Geophys. Res., 108(E6), 5152, 10.1029/2002JE001960, 2003.
3. Sugita, S., P. H. Schultz, and S. Hasegawa, Intensities of atomic lines and molecular bands observed in impact-induced luminescence, J. Geophys. Res., 108(E12), 5140, doi:10.1029/2003JE002156, 2003.