講演情報
[PPS02-P18]Establish reference materials for lunar surface explorations
*新原 隆史1、小西 里空1、寳城 百萌花1、長岡 央2、仲内 悠祐2、白井 直樹3、横山 立憲4、鏡味 沙耶4 (1.岡山理科大学、2.立命館大学、3.神奈川大学、4.日本原子力研究開発機構)
キーワード：
月探査、月隕石、標準試料
Developing in situ analytical instruments is crucial for the next generation of deep space exploration, which aims to obtain lunar resources and scientific data. To obtain accurate data from crewed and uncrewed missions, instruments must be calibrated using terrestrial or actual lunar samples.
One target material for instrument calibration is lunar meteorites. However, there are significant differences in sample shape between petrological measurements in a laboratory and in situ measurements on the lunar surface. Petrological studies often use polished sections for optical and scanning electron microscopes (SEM) with energy dispersive spectroscopy (EDS) and electron microprobes (EPMA). These polished sections are coated with carbon to prevent charging during SEM and EPMA measurements. These observations connect petrological structures and mineral compositions. However, it is difficult to create such sections for in situ measurements. In situ measurements analyze rough surfaces. Therefore, we must make a direct comparison between the quantitative data obtained from polished sections and the quantitative data obtained from rough-surface rock slabs in order to calibrate in situ instruments.Currently, we are trying to establish reference material for instrument calibration. This data includes high-quality quantitative data obtained from polished sections, as well as mineral distribution maps for rough surfaces. We have collected a variety of terrestrial rocks and lunar meteorites.
The current plan is to create a mineral distribution map using samples of rough surfaces. Since rock specimens are nonconductive, a carbon coating is necessary for SEM-EDS and EPMA analysis. However, our current goal is to use the sample with in situ instruments, so we cannot coat it with carbon because coating a lunar surface is difficult. Therefore, we will measure the rock specimen without a carbon coating. First, we tested terrestrial samples of basalt, diorite, and granite. During high-vacuum SEM observation, we encountered a charge-up problem. Basaltic samples were less affected, while granite was highly affected, especially on the plane surfaces of plagioclase crystals. Basaltic samples also contain plagioclase, but the grain size is small, which prevents severe charging. Lunar meteorites (mostly feldspathic breccia) also cause severe charging due to the flat surfaces of plagioclase crystals. We obtained elemental distribution maps using EDS and generated mineral distribution maps using the elemental maps. We identify phases using micro-Raman spectroscopy. For the lunar samples, we plan to analyze in Low Vacuum mode on the SEM to obtain similar data and avoid charging. To this end, we will test the accuracy and precision of the data by comparing it with data obtained in high vacuum. We plan to create archives including mineral composition, mineral maps, and petrological information for engineering use.
One target material for instrument calibration is lunar meteorites. However, there are significant differences in sample shape between petrological measurements in a laboratory and in situ measurements on the lunar surface. Petrological studies often use polished sections for optical and scanning electron microscopes (SEM) with energy dispersive spectroscopy (EDS) and electron microprobes (EPMA). These polished sections are coated with carbon to prevent charging during SEM and EPMA measurements. These observations connect petrological structures and mineral compositions. However, it is difficult to create such sections for in situ measurements. In situ measurements analyze rough surfaces. Therefore, we must make a direct comparison between the quantitative data obtained from polished sections and the quantitative data obtained from rough-surface rock slabs in order to calibrate in situ instruments.Currently, we are trying to establish reference material for instrument calibration. This data includes high-quality quantitative data obtained from polished sections, as well as mineral distribution maps for rough surfaces. We have collected a variety of terrestrial rocks and lunar meteorites.
The current plan is to create a mineral distribution map using samples of rough surfaces. Since rock specimens are nonconductive, a carbon coating is necessary for SEM-EDS and EPMA analysis. However, our current goal is to use the sample with in situ instruments, so we cannot coat it with carbon because coating a lunar surface is difficult. Therefore, we will measure the rock specimen without a carbon coating. First, we tested terrestrial samples of basalt, diorite, and granite. During high-vacuum SEM observation, we encountered a charge-up problem. Basaltic samples were less affected, while granite was highly affected, especially on the plane surfaces of plagioclase crystals. Basaltic samples also contain plagioclase, but the grain size is small, which prevents severe charging. Lunar meteorites (mostly feldspathic breccia) also cause severe charging due to the flat surfaces of plagioclase crystals. We obtained elemental distribution maps using EDS and generated mineral distribution maps using the elemental maps. We identify phases using micro-Raman spectroscopy. For the lunar samples, we plan to analyze in Low Vacuum mode on the SEM to obtain similar data and avoid charging. To this end, we will test the accuracy and precision of the data by comparing it with data obtained in high vacuum. We plan to create archives including mineral composition, mineral maps, and petrological information for engineering use.