Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu

Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estim...

Full description

Bibliographic Details
Published in:Journal of Geophysical Research: Planets
Main Authors: Grott, Matthias, Biele, Jens, Michel, Patrick, Sugita, Seiji, Schröder, Stefan, Sakatani, Naoya, Neumann, Wladimir, Kameda, Shingo, Michikami, Tatsuhiro, Honda, Chikatoshi, 2 German Aerospace Center Cologne Germany, 3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France, 4 University of Tokyo Tokyo Japan, 1 German Aerospace Center Berlin Germany, 5 ISAS/JAXA Sagamihara Japan, 7 Rikkyo University Tokyo Japan, 8 Kindai University Hiroshima Japan, 9 University of Aizu Aizu‐Wakamatsu Japan
Format: Article in Journal/Newspaper
Language:English
Published: 2020
Subjects:
Online Access:https://doi.org/10.1029/2020JE006519
http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8427
id ftsubggeo:oai:e-docs.geo-leo.de:11858/8427
record_format openpolar
spelling ftsubggeo:oai:e-docs.geo-leo.de:11858/8427 2024-06-09T07:49:53+00:00 Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu Grott, Matthias Biele, Jens Michel, Patrick Sugita, Seiji Schröder, Stefan Sakatani, Naoya Neumann, Wladimir Kameda, Shingo Michikami, Tatsuhiro Honda, Chikatoshi 2 German Aerospace Center Cologne Germany 3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France 4 University of Tokyo Tokyo Japan 1 German Aerospace Center Berlin Germany 5 ISAS/JAXA Sagamihara Japan 7 Rikkyo University Tokyo Japan 8 Kindai University Hiroshima Japan 9 University of Aizu Aizu‐Wakamatsu Japan 2020-12-04 https://doi.org/10.1029/2020JE006519 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8427 eng eng doi:10.1029/2020JE006519 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8427 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ddc:523 Asteroids Ryugu Porosity Density doc-type:article 2020 ftsubggeo https://doi.org/10.1029/2020JE006519 2024-05-10T04:58:51Z Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estimated based on comparisons between the asteroid bulk density and both the bulk and grain density of meteorite analogs, and relatively large macroporosities are usually obtained. Here we use semiempirical models for the macroporosity of multicomponent mixtures to determine Ryugu's macroporosity based on the observed size‐frequency distribution (SFD) of boulders on the surface. We find that Ryugu's macroporosity can be significantly smaller than usually assumed, as the observed SFD allows for an efficient packing of boulders, resulting in a macroporosity of 16% ± 3%. Therefore, we confirm that Ryugu's high bulk porosity is a direct consequence of a very large boulder microporosity. Furthermore, using estimates of boulder microporosity of around 50% as derived from in situ measurements, the average grain density in boulders is 2,848 ± 152 kg m–3, similar to values obtained for CM and the Tagish lake meteorites. Ryugu's bulk porosity corresponding to the above values is 58%. Thus, the macroporosity of rubble pile asteroids may have been systematically overestimated in the past. Plain Language Summary: The carbonaceous asteroid (162173) Ryugu formed from fragments which reaccreted after its parent body was disrupted by a catastrophic collision. Asteroids of this type are also known as rubble piles and the reaccumulation process is thought to be one of the causes for their large bulk porosity. We have applied mixing models to determine the amount of interboulder porosity taking the observed abundance of large and small boulders on the surface into account. We find that the relative abundances of differently sized boulders allow for a very efficient packing, such that interboulder porosity in Ryugu is rather small and only ... Article in Journal/Newspaper Tagish GEO-LEOe-docs (FID GEO) Ryugu ENVELOPE(44.033,44.033,-67.967,-67.967) Tagish ENVELOPE(-134.272,-134.272,60.313,60.313) Tagish Lake ENVELOPE(-134.233,-134.233,59.717,59.717) Journal of Geophysical Research: Planets 125 12
institution Open Polar
collection GEO-LEOe-docs (FID GEO)
op_collection_id ftsubggeo
language English
topic ddc:523
Asteroids
Ryugu
Porosity
Density
spellingShingle ddc:523
Asteroids
Ryugu
Porosity
Density
Grott, Matthias
Biele, Jens
Michel, Patrick
Sugita, Seiji
Schröder, Stefan
Sakatani, Naoya
Neumann, Wladimir
Kameda, Shingo
Michikami, Tatsuhiro
Honda, Chikatoshi
2 German Aerospace Center Cologne Germany
3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France
4 University of Tokyo Tokyo Japan
1 German Aerospace Center Berlin Germany
5 ISAS/JAXA Sagamihara Japan
7 Rikkyo University Tokyo Japan
8 Kindai University Hiroshima Japan
9 University of Aizu Aizu‐Wakamatsu Japan
Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
topic_facet ddc:523
Asteroids
Ryugu
Porosity
Density
description Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estimated based on comparisons between the asteroid bulk density and both the bulk and grain density of meteorite analogs, and relatively large macroporosities are usually obtained. Here we use semiempirical models for the macroporosity of multicomponent mixtures to determine Ryugu's macroporosity based on the observed size‐frequency distribution (SFD) of boulders on the surface. We find that Ryugu's macroporosity can be significantly smaller than usually assumed, as the observed SFD allows for an efficient packing of boulders, resulting in a macroporosity of 16% ± 3%. Therefore, we confirm that Ryugu's high bulk porosity is a direct consequence of a very large boulder microporosity. Furthermore, using estimates of boulder microporosity of around 50% as derived from in situ measurements, the average grain density in boulders is 2,848 ± 152 kg m–3, similar to values obtained for CM and the Tagish lake meteorites. Ryugu's bulk porosity corresponding to the above values is 58%. Thus, the macroporosity of rubble pile asteroids may have been systematically overestimated in the past. Plain Language Summary: The carbonaceous asteroid (162173) Ryugu formed from fragments which reaccreted after its parent body was disrupted by a catastrophic collision. Asteroids of this type are also known as rubble piles and the reaccumulation process is thought to be one of the causes for their large bulk porosity. We have applied mixing models to determine the amount of interboulder porosity taking the observed abundance of large and small boulders on the surface into account. We find that the relative abundances of differently sized boulders allow for a very efficient packing, such that interboulder porosity in Ryugu is rather small and only ...
format Article in Journal/Newspaper
author Grott, Matthias
Biele, Jens
Michel, Patrick
Sugita, Seiji
Schröder, Stefan
Sakatani, Naoya
Neumann, Wladimir
Kameda, Shingo
Michikami, Tatsuhiro
Honda, Chikatoshi
2 German Aerospace Center Cologne Germany
3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France
4 University of Tokyo Tokyo Japan
1 German Aerospace Center Berlin Germany
5 ISAS/JAXA Sagamihara Japan
7 Rikkyo University Tokyo Japan
8 Kindai University Hiroshima Japan
9 University of Aizu Aizu‐Wakamatsu Japan
author_facet Grott, Matthias
Biele, Jens
Michel, Patrick
Sugita, Seiji
Schröder, Stefan
Sakatani, Naoya
Neumann, Wladimir
Kameda, Shingo
Michikami, Tatsuhiro
Honda, Chikatoshi
2 German Aerospace Center Cologne Germany
3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France
4 University of Tokyo Tokyo Japan
1 German Aerospace Center Berlin Germany
5 ISAS/JAXA Sagamihara Japan
7 Rikkyo University Tokyo Japan
8 Kindai University Hiroshima Japan
9 University of Aizu Aizu‐Wakamatsu Japan
author_sort Grott, Matthias
title Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
title_short Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
title_full Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
title_fullStr Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
title_full_unstemmed Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu
title_sort macroporosity and grain density of rubble pile asteroid (162173) ryugu
publishDate 2020
url https://doi.org/10.1029/2020JE006519
http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8427
long_lat ENVELOPE(44.033,44.033,-67.967,-67.967)
ENVELOPE(-134.272,-134.272,60.313,60.313)
ENVELOPE(-134.233,-134.233,59.717,59.717)
geographic Ryugu
Tagish
Tagish Lake
geographic_facet Ryugu
Tagish
Tagish Lake
genre Tagish
genre_facet Tagish
op_relation doi:10.1029/2020JE006519
http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8427
op_rights This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
op_doi https://doi.org/10.1029/2020JE006519
container_title Journal of Geophysical Research: Planets
container_volume 125
container_issue 12
_version_ 1801382780331884544