Crater depth-to-diameter ratios on asteroid 162173 Ryugu

Noguchi, Rina; Hirata, Naoyuki; Hirata, Naru; Shimaki, Y.; Nishikawa, Naoki; Tanaka, Shimako; Sugiyama, Tomoshi; Morota, Tomokatsu; Sugita, Seiji; Cho, Yuichiro; Honda, Rie; Kameda, Shingo; Tatsumi, Eri; Yoshioka, Kazuo; Sawada, Hirotaka; Yokota, Yasuhiro; Sakatani, Naoya; Hayakawa, Masahiko; Matsuoka, Moe; Kouyama, T.; Suzuki, Hidehiko; Honda, Chikatoshi; Ogawa, Kazunori; Kanamaru, Masanori; Watanabe, S.

doi:10.1016/j.icarus.2020.114016

Cited by 17 publications

(32 citation statements)

References 30 publications

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“…Both studies used a different approach than the one used here. The Sugita et al (2019) results suggest that craters on Ryugu are deeper than craters on Bennu, whereas the Noguchi et al (2021) results are similar to the results for Bennu. Thomas et al (1999) reported that the d/D of four craters on Mathilde ranged from 0.12 to 0.25, with uncertainties of at least 25%, which suggests that craters on Mathilde tend to be deeper than those on Bennu or Ryugu.…”

Section: Discussionmentioning

confidence: 77%

“…Sugita et al (2019) reported that the d/D of a few impact craters on Ryugu larger than 20 m in diameter ranged from 0.14 to 0.2. Noguchi et al (2021) report that the mean d/D of all 77 craters on Ryugu is 0.09 ± 0.02, with a range of 0.03–0.15. Noguchi et al (2021) attribute the differences between the two studies to differences in how the measurements were made (see Figure S1 in Noguchi et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

“…Noguchi et al (2021) report that the mean d/D of all 77 craters on Ryugu is 0.09 ± 0.02, with a range of 0.03–0.15. Noguchi et al (2021) attribute the differences between the two studies to differences in how the measurements were made (see Figure S1 in Noguchi et al, 2021). Both studies used a different approach than the one used here.…”

Section: Discussionmentioning

confidence: 99%

“…Impact crater depth-to-diameter relationships (d/D) have been studied on several asteroids, including Vesta, Lutetia, Steins, Ida, Mathilde, Eros, Gaspra, and Itokawa; see Marchi et al (2015) for a review. Preliminary results for a few large craters on asteroid (162173) Ryugu have also been reported (Noguchi et al, 2021). Here, we assess d/D on Bennu to characterize its impact craters and assess the implications for its surface and interior.…”

Section: Introductionmentioning

confidence: 92%

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The Morphometry of Impact Craters on Bennu

Daly

Bierhaus

Barnouin

et al. 2020

Geophysical Research Letters

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Bennu is an~500-m-diameter rubble-pile asteroid that is the target of detailed study by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Here we use data from the OSIRIS-REx Laser Altimeter to assess depth-to-diameter ratios (d/D) of 108 impact craters larger than 10 m in diameter. The d/D of craters on Bennu ranges from 0.02 to 0.19. The mean is 0.10 ± 0.03. The smallest craters show the broadest range in d/D, consistent with d/D measurements on other asteroids. A few craters have central mounds, which is interpreted as evidence that a more competent substrate lies a few meters beneath them. The range of d/D narrows as crater size increases, with craters larger than 80 m tending toward smaller d/D. At large scales, increases in target strength with depth, combined with target curvature, may affect crater morphometry.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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The Morphometry of Impact Craters on Bennu

Daly

Bierhaus

Barnouin

et al. 2020

Geophysical Research Letters

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“…Subsequently, more detailed investigation on the spatial distribution of craters was conducted, finding a latitudinal variation in crater number density (Hirata et al., 2020). Crater depth‐to‐diameter ( d / D ) ratios were then measured based on the shape model of Ryugu (Noguchi et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

Geologic History and Crater Morphology of Asteroid (162173) Ryugu

et al. 2021

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Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high‐resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant boulders on and under the surface of the rubble‐pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well‐defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter > 100 m) host abundant and sometimes unproportionally large boulders on their floors. Small craters (<20 m) are characterized by smooth circular floors distinguishable from the boulder‐rich exterior. Such small craters tend to have dark centers of unclear origin. The correlation between crater size and boulder number density suggests that some processes sort the size of boulders in the shallow (<30 m) subsurface. Furthermore, the crater size‐frequency distributions (CSFDs) of different regions on Ryugu record multiple geologic events, revealing the diverse geologic history on this 1‐km asteroid. Our crater‐counting analyses indicate that the equatorial ridge is the oldest structure of Ryugu and was formed 23–30 Myr ago. Then, Ryugu was partially resurfaced, possibly by the impact that formed the Urashima crater 5–12 Myr ago. Subsequently, a large‐scale resurfacing event formed the western bulge and the fossae 2–9 Myr ago. Following this process, the spin of Ryugu slowed down plausibly due to the YORP effect. The transition of isochrons in a CSFD suggests that Ryugu was decoupled from the main belt and transferred to a near‐Earth orbit 0.2–7 Myr ago.

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Geologic History and Crater Morphology of Asteroid (162173) Ryugu

Cho

Morota

Kanamaru

et al. 2021

Preprint

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Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high-resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant boulders on and under the surface of the rubble-pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well-defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter > 100 m) host abundant and sometimes unproportionally large boulders on their floors. Small craters (<20 m) are characterized by smooth circular floors distinguishable from the boulder-rich exterior. Such small craters tend to have dark centers of unclear origin. The correlation between crater size and boulder number density suggests that some processes sort the size of boulders in the shallow (<30 m) subsurface. Furthermore, the crater size-frequency distributions (CSFDs) of different regions on Ryugu record multiple geologic events, revealing the diverse geologic history on this 1-km asteroid. Our crater-counting analyses indicate that the equatorial ridge is the oldest structure of Ryugu and was formed 23-30 Myr ago. Then, Ryugu was partially resurfaced, possibly by the impact that formed the Urashima crater 5-12 Myr ago. Subsequently, a large-scale resurfacing event formed the western bulge and the fossae 2-9 Myr ago. Following this process, the spin of Ryugu slowed down plausibly due to the YORP effect. The transition of isochrons in a CSFD suggests that Ryugu was decoupled from the main belt and transferred to a near-Earth orbit 0.2-7 Myr ago.

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Crater depth-to-diameter ratios on asteroid 162173 Ryugu

Cited by 17 publications

References 30 publications

The Morphometry of Impact Craters on Bennu

The Morphometry of Impact Craters on Bennu

Geologic History and Crater Morphology of Asteroid (162173) Ryugu

Geologic History and Crater Morphology of Asteroid (162173) Ryugu

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