Hiroshi Imanaka

Hiroshi Imanaka
Senior Scientist
Curriculum Vitae: 

Dr. Imanaka's major research interest is the inventory and evolution of the volatile CHNOS elements in planetary atmospheres, planetary surfaces, and, the early solar system towards the understanding of the origin and evolution of life and habitable environments. 
He is working on comprehensive laboratory studies of complex organic chemistry related to the atmospheres of Titan and the early Earth. He studies characteristic fingerprints (elemental/isotopic composition, structure, and spectroscopic characteristics) in plausible organic macromolecules in planetary environments.
A comprehensive understanding of such fingerprints is a key for constraining the physical-chemical environments, elemental cycles, and energy balance from available, or potentially available, sets of astronomical/planetary/geological observations. 

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Laboratory measurements of the optical constants of complex organic matter

Understanding the chemical nature of haze particles in the atmospheres of Titan and Saturn and materials on the surface of the Saturn system bodies is one of the goals of the Cassini-Huygens mission. Complex organic materials may exist as haze layers in the atmospheres of Titan and Saturn and as dark coloring agents on icy satellite surfaces. Laboratory measurements of optical constants of laboratory haze/condensate analogs at broad spectral wavelengths are crucial for the effort of interpreting the spectral observations by the Cassini-Huygens mission. However, there is a general lack of studies in vacuum ultraviolet, near-IR, and far-IR spectral regions, which is necessary for the Cassini’s UVIS, VIMS, and CIRS instruments. We propose to determine the optical constants of laboratory-generated complex organic matter in the wavelength region between 0.030 μm and 500 μm (20 cm-1), which covers spectral region crucial for the Cassini spectroscopic instruments (the UVIS, ISS, VIMS, and CIRS) and the DISR on the Huygens Probe. Our initial effort would be focused on the plausible organic hazes in Titan and Saturn by investigating complex organic materials 1) with/without nitrogen inclusion and 2) various degree of saturation [(H-N)/C]. Comlex organics consisting of C/H/O elements will also be investigated as potential organic matter on the surface of icy bodies and Saturn’s ring particles. Reliable optical constants from this proposed work would help the effort in interpretation of broad spectral observations by the Cassini mission to constrain the chemical and physical nature of those organic haze materials.

Organic Aerosols in the Early Earth Atmosphere: Reaction Network an Its Isotope Signature

Experimental simulations of Titan's atmospheric and surface chemistries in order to understand the formation of complex organic molecules as well as the abiotic formation of prebiotic molecules, providing important clues to the origin of life on the early Earth.