Engineering topics

Nakashima, S.

Publications and source records attributed to Nakashima, S..

3 records

NASA NTRS2005

In-Situ Heating Decrease Kinetics of Aliphatic Hydrocarbons in Tagish Lake Meteorite by Micro-FTIR

Carbonaceous chondrites are known to contain up to 3wt.% C, the major part of which corresponds to a macromolecular organic fraction. Chondritic organic matter is based on small aromatic units, cross-linked by short aliphatic chains rather than large clusters of polyaromatic structures. Two main characteristic features of those organics measured by FTIR are: (1) an equivalent intensity of the asymmetric stretching mode absorptions for CH3 (2960/cm) and CH2 (2920/cm) and (2) a lack of aromatic CH-stretching mode (3040/cm). Tagish Lake is a new type of water- and carbon-rich type 2 carbonaceous chondrite. Its total carbon content is approx. 5 wt%, of which the organic carbon content reaches approx. 1.3 wt%. Tagish Lake may have never experienced temperatures higher than 120 C after formation of organics based on the disappearance of infrared (IR) organic peaks in step heating experiments. Here we report in-situ kinetic heating experiments of organics in Tagish Lake by micro-FTIR to characterize the nature of aliphatic hydrocarbons and their thermal stabilities.

Kebukawa, Y.↗

NASA NTRS2005

Infrared Micro-Spectroscopy of Organic and Hydrous Components in Some Antarctic Micrometeorites

Micrometeorites extracted from Antarctic ice are a major source of extraterrestrial materials available for study in the laboratory. Materials in this size range are important because the peak in the mass flux distribution of extraterrestrial particles accreted by the Earth occurs for particles approximately 200 microns in diameter with a mass accretion rate estimated at approximately 40 x 10(exp 6) kilograms per year. It has been suggested that micrometeorites may have contributed much pre-biotic organic matter to the early Earth, but the types and abundances of organic material in micrometeorites are poorly known. We have conducted infrared (IR) micro-spectrocopy of small micrometeorites (about 100 microns in size) in order to characterize organic matter that is present in the particles. The obtained results were compared with IR signatures of representative carbonaceous chondrites.

Suzuki, A.↗

NASA NTRS2003

In Situ Heating Behavior by Infrared Microspectroscopy of Organic Components in Tagish Lake Meteorite

The Tagish Lake meteorite is a new type of water- and carbon-rich carbonaceous chondrite. Its total carbon content is approx. 5 wt% and the organic carbon content reaches approx.1.3 wt%. We reported from the Tagish Lake sample#TL3B6 the first in situ observation of the hollow organic globules. TL3B6 is generally enriched in the organic globules that consist of aliphatic and oxygenated functionality similar to the material produced by the laboratory simulation of UV photolysis of interstellar ice analogs suggesting that the organic globules in Tagish Lake may be extremely primitive organic material that formed before or during the formation of the solar system. Here we report the micro-sampling FTIR analysis of the TL3B6 and the in situ step heating experiments: which can allow us to place 1) significant constraints on the organic functionality in Tagish Lake; 2) the thermal stability of the organics; and 3) thermal history of the meteorite and its parent body. For comparison, the membranous films formed from hydrothermal reaction of an OH-bearing amino acid (theronine: Thr) and silica mixture were examined.

Nakamura, K.↗