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Possibility of estimating particle size and porosity on Ryugu through MARA temperature measurements

Ogawa, Kazunori and Hamm, Maximilian and Grott, Matthias and Sakatani, N. and Knollenberg, Jörg and Biele, Jens (2019) Possibility of estimating particle size and porosity on Ryugu through MARA temperature measurements. Icarus: International Journal of Solar System Studies, 333, pp. 318-322. Elsevier. DOI: 10.1016/j.icarus.2019.06.014 ISSN 0019-1035

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Official URL: https://www.sciencedirect.com/science/article/abs/pii/S0019103518305852


We investigated whether the MASCOT/MARA thermal radiometer can be used to determine regolith particle size and porosity on the asteroid Ryugu in the Hayabusa2 mission. We used a one-dimensional heat flow model and our own thermal conductivity model for regolith to compare MARA's performance and the expected Ryugu surface temperatures of various particle sizes and porosities. The results showed that MARA is capable of constraining particle size with ±30% uncertainty if particle size is near 4.25 mm and near-surface porosity is near 60% (a fraction of void spaces between regolith particles in a unit volume), assuming certain physical properties of regolith particles. The porosity cannot be constrained meaningfully through MARA observations alone; however, it is constrained with uncertainty of ±10% around 50% and ±5% around 70% with 2σ probability if other supportive observations (by the MASCOT camera) provide the particle size. The results also show that nighttime temperature is more sensitive to the particle size and porosity variations and its observation is essential to achieve the small error ranges, while MARA is the only instrument to observe the nighttime temperature on Ryugu. In this study, the surface roughness effect in insolation and thermal radiations was neglected. The roughness effect is presumed to be less influential in nighttime, however, this effect must be carefully considered in actual data analysis of MARA.

Item URL in elib:https://elib.dlr.de/130712/
Document Type:Article
Title:Possibility of estimating particle size and porosity on Ryugu through MARA temperature measurements
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ogawa, KazunoriDep. of Planetology, Kobe University, Kobe - JapanUNSPECIFIED
Hamm, Maximilianmaximilian.hamm (at) dlr.deUNSPECIFIED
Grott, MatthiasMatthias.Grott (at) dlr.deUNSPECIFIED
Sakatani, N.Institute of Space and Astronautical Science , Japan Aerospace Exploration Agency (ISAS / JAXA) ( 3 - 1 - 1 Yoshinodai, Chuo - Ku, Sa gamihara 2 52 - 5210 , JapanUNSPECIFIED
Knollenberg, JörgJoerg.Knollenberg (at) dlr.deUNSPECIFIED
Biele, JensJens.Biele (at) dlr.deUNSPECIFIED
Date:15 November 2019
Journal or Publication Title:Icarus: International Journal of Solar System Studies
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1016/j.icarus.2019.06.014
Page Range:pp. 318-322
Keywords:MASCOT Hayabusa2 Asteroids Ryugu Regolith Physical Properties
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):Project MASCOT Science and operation
Location: Berlin-Adlershof , Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space > Institute of Space Simulation > User center for space experiments (MUSC)(only for search)
Institute of Planetary Research > Planetary Physics
Institute of Planetary Research > Asteroids and Comets
Deposited By: Grott, Dr.rer.nat. Matthias
Deposited On:18 Nov 2019 09:16
Last Modified:18 Nov 2019 09:16

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