16:15 〜 16:30
[PPS05-04] Phobos and Deimos surface: analog samples studies to interpret the composition and physical properties
キーワード：Phobos, Deimos, MMX, laboratory spectroscopy, analog sample, MIRS
JAXA Martian Moon eXploration (MMX) sample return mission [1], will study in detail Phobos and Deimos, the two moon of Mars, to investigate their origin and to collect a sample from the surface of Phobos, the biggest moon. Despite the data available so far, the composition of the two moons is still unclear with possible presence of hydrated minerals but also mafic minerals (i.e. olivine and pyroxene). MIRS spectrometer [2] on-board MMX mission will be pivotal to unveil the open question on the composition of Phobos and Deimos and to provide global maps of the satellites surfaces along with detailed observation of the possible landing site of the mission. As part of the global campaign in preparation of MMX mission, we reviewed past spectroscopic observations of the Martian moons and we performed dedicated new laboratory measurements on analog mineral mixing and meteorites to match the satellites spectral behavior and understand the physical properties of the regolith on the surface [3].
Several sample were prepared mixing of analog of Mars soil and carbonaceous chondrites and dark component (i.e. synthetic amorphous carbon) with different hydrated and anhydrous mineral with different proportions and grain sizes. Some meteorites were also selected. New measurements were acquired at INAF-Astrophysical Observatory of Arcetri and IPAG Grenoble laboratories at room conditions exploring different geometries. The wavelength range was investigated from visible and near infrared (VIS-NIR) to medium infrared (MIR) and compared with the data collected from past space missions and ground telescope in both the range.
From our first laboratory experiments, the results suggest that the surface of Phobos and Deimos can be associated with samples characterized by a high presence of dark components (e.g. carbonaceous chondrite simulants and amorphous carbon) over a bright component (Mars simulant or hydrated/anhydrous minerals). Some of the laboratory spectra obtained in our experiment are visible in Figure 1. We investigate mixture with amorphous carbon from low concentration to very high (spanning from 1% to 90%). Our results show that presence of dark component, even if in small percentage, could also be responsible for the reduced hydrated band observed on the Martian moons without invoking dehydration or OH-implantation on anhydrous surface. Mixtures of analogs minerals are in agreement with respect to the hydrated band at 2.7 micron observed in Phobos spectra but some sample are less comparable in terms of slopes with the observations. In the presentation we will review the state of art of Phobos and Deimos observations and we will present the ongoing campaign carried on by the MIRS science team to study spectroscopic analogs.
Figure 1 caption. Comparison between Phobos and Deimos normalized spectra from Rivkin et al 2002 and single scattering albedo (SSA) from Fraeman et al 2014 with laboratory reflectance infrared spectra. In detail here are reported three mixtures: wt.99% amorphous carbon + wt.1% serpentine (MIX#06), wt.90% amorphous carbon + wt.10% basalt (MIX#05) and wt.90% CR meteorite simulant + wt.10% Mars simulant (MIX#04). In addition, we report the pure CR meteorite simulant (sCR) and two meteorites: Tarda and WIS91600 (figure adapted from Poggiali et al 2022).
Acknowledgments: This study was carried out in support of the MIRS instrument financed by CNES. Some samples used in this work were produced by the ExolithLab and/or shared personally by D. Britt to INAF-Arcetri laboratory.
References: [1] Kuramoto K. et al. (2022) Earth, Planets and Space, 74, 12 [2] Barucci M. A. et al. (2021) Earth Planets Space, 73, 211. [3] Poggiali G. et al. (2022) MNRAS, 516, 1, 465–476
Several sample were prepared mixing of analog of Mars soil and carbonaceous chondrites and dark component (i.e. synthetic amorphous carbon) with different hydrated and anhydrous mineral with different proportions and grain sizes. Some meteorites were also selected. New measurements were acquired at INAF-Astrophysical Observatory of Arcetri and IPAG Grenoble laboratories at room conditions exploring different geometries. The wavelength range was investigated from visible and near infrared (VIS-NIR) to medium infrared (MIR) and compared with the data collected from past space missions and ground telescope in both the range.
From our first laboratory experiments, the results suggest that the surface of Phobos and Deimos can be associated with samples characterized by a high presence of dark components (e.g. carbonaceous chondrite simulants and amorphous carbon) over a bright component (Mars simulant or hydrated/anhydrous minerals). Some of the laboratory spectra obtained in our experiment are visible in Figure 1. We investigate mixture with amorphous carbon from low concentration to very high (spanning from 1% to 90%). Our results show that presence of dark component, even if in small percentage, could also be responsible for the reduced hydrated band observed on the Martian moons without invoking dehydration or OH-implantation on anhydrous surface. Mixtures of analogs minerals are in agreement with respect to the hydrated band at 2.7 micron observed in Phobos spectra but some sample are less comparable in terms of slopes with the observations. In the presentation we will review the state of art of Phobos and Deimos observations and we will present the ongoing campaign carried on by the MIRS science team to study spectroscopic analogs.
Figure 1 caption. Comparison between Phobos and Deimos normalized spectra from Rivkin et al 2002 and single scattering albedo (SSA) from Fraeman et al 2014 with laboratory reflectance infrared spectra. In detail here are reported three mixtures: wt.99% amorphous carbon + wt.1% serpentine (MIX#06), wt.90% amorphous carbon + wt.10% basalt (MIX#05) and wt.90% CR meteorite simulant + wt.10% Mars simulant (MIX#04). In addition, we report the pure CR meteorite simulant (sCR) and two meteorites: Tarda and WIS91600 (figure adapted from Poggiali et al 2022).
Acknowledgments: This study was carried out in support of the MIRS instrument financed by CNES. Some samples used in this work were produced by the ExolithLab and/or shared personally by D. Britt to INAF-Arcetri laboratory.
References: [1] Kuramoto K. et al. (2022) Earth, Planets and Space, 74, 12 [2] Barucci M. A. et al. (2021) Earth Planets Space, 73, 211. [3] Poggiali G. et al. (2022) MNRAS, 516, 1, 465–476