13:45 〜 14:00
[PPS03-11] The Next Generation small-body Sample Return mission: Scientific strategies of in-situ analyses
★Invited Papers
キーワード：NGSR、サンプルリターン、彗星、小天体
The Next Generation small-body Sample Return (NGSR) working group is planning a sample return mission from a comet, aiming to launch in the 2030s. The NGSR plans to explore and return samples of cometary surface and subsurface to elucidate the origin of solar-system materials and the origin of solar-system bodies. However, since it is difficult to return samples of highly volatile compounds and it takes many years to return samples, in-situ analysis mainly by a high-resolution mass spectrometer (HRMS) is also planned. In this presentation, we will introduce the science purposes, configurations of the HRMS system, and operational strategies for the in-situ analysis of cometary materials on the NGSR mission.
The scientific goals of the in-situ analysis on the NGSR mission are as follows:
(1) To determine the molecular compositions and abundances of the volatile compounds from the comet.
(2) To determine the noble gases and isotopic compositions of the cometary materials.
(3) To elucidate the differences in organic matter between surface and subsurface materials from the comet.
(4) To elucidate the origin of cometary organic matter.
(5) To elucidate the genetic relationship between cometary organic matter and primitive asteroidal organic matter.
(6) To understand the distribution of raw materials for life that could be supplied by comets to the early Earth.
To achieve the above goals, a HRMS system is under development based on a multi-turn time-of-flight mass spectrometer for space usage with a mass resolution of 8000 for isotope ratio measurements of C, H, N, and O, and identification of molecules up to m/z 200. For molecule analyses, the collected samples from surface and subsurface of the comet are sequentially heated to around room temperature, 100°C, 200°C, and 400°C (400°C is extra), and the gas species produced at each temperature are analyzed directory by the HRMS. For isotope analyses, in addition to the above step-wise heating, the gases produced at each temperature are subsequently introduced into a high-temperature (>1000°C) pyrolizer, and the bulk isotopic compositions at each temperature are determined. Note that high-temperature pyrolysis is not necessary for isotope measurements of low-molecular compounds such as H2O. As extra, gas-chromatography system is considered to more reliable identifications of molecular species. In addition, direct analyses of the gaseous species around the comet will be performed (sniff mode), to determine the distribution of volatiles and the D/H ratio of water around the comet.
The combined analysis with in situ mass spectrometry and sample return on a target body represents a novel approach not yet achieved in ongoing or previous space exploration missions. This is crucial because information gathered from observations or in situ analysis, such as the Rosetta mission, differs significantly from that obtained from sample return missions, such as Stardust and Hayabusa2 missions. Thus, acquiring both types of information from the same sample is essential to fully understand cometary materials. Such an approach serves as a link between chemistry derived from observational studies and that from extraterrestrial material analyses, facilitating a seamless understanding of chemical processes from disk chemistry to small body chemistry.
The scientific goals of the in-situ analysis on the NGSR mission are as follows:
(1) To determine the molecular compositions and abundances of the volatile compounds from the comet.
(2) To determine the noble gases and isotopic compositions of the cometary materials.
(3) To elucidate the differences in organic matter between surface and subsurface materials from the comet.
(4) To elucidate the origin of cometary organic matter.
(5) To elucidate the genetic relationship between cometary organic matter and primitive asteroidal organic matter.
(6) To understand the distribution of raw materials for life that could be supplied by comets to the early Earth.
To achieve the above goals, a HRMS system is under development based on a multi-turn time-of-flight mass spectrometer for space usage with a mass resolution of 8000 for isotope ratio measurements of C, H, N, and O, and identification of molecules up to m/z 200. For molecule analyses, the collected samples from surface and subsurface of the comet are sequentially heated to around room temperature, 100°C, 200°C, and 400°C (400°C is extra), and the gas species produced at each temperature are analyzed directory by the HRMS. For isotope analyses, in addition to the above step-wise heating, the gases produced at each temperature are subsequently introduced into a high-temperature (>1000°C) pyrolizer, and the bulk isotopic compositions at each temperature are determined. Note that high-temperature pyrolysis is not necessary for isotope measurements of low-molecular compounds such as H2O. As extra, gas-chromatography system is considered to more reliable identifications of molecular species. In addition, direct analyses of the gaseous species around the comet will be performed (sniff mode), to determine the distribution of volatiles and the D/H ratio of water around the comet.
The combined analysis with in situ mass spectrometry and sample return on a target body represents a novel approach not yet achieved in ongoing or previous space exploration missions. This is crucial because information gathered from observations or in situ analysis, such as the Rosetta mission, differs significantly from that obtained from sample return missions, such as Stardust and Hayabusa2 missions. Thus, acquiring both types of information from the same sample is essential to fully understand cometary materials. Such an approach serves as a link between chemistry derived from observational studies and that from extraterrestrial material analyses, facilitating a seamless understanding of chemical processes from disk chemistry to small body chemistry.