Measurement of Impact Ejecta from Regolith Targets in Oblique Impacts

Yamamoto, Sakae

doi:10.1006/icar.2002.6862

Cited by 21 publications

(12 citation statements)

References 24 publications

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“…Asymmetrical ejecta distribution caused by low-angle impact has been documented by many studies (e.g., Anderson et al, 2003;Bottke et al, 2000;Davison et al, 2011;Gault & Wedekind, 1978;Herrick & Hessen, 2006;Pierazzo & Melosh, 2000;500 Schultz et al, 2007;Shuvalov, 2011;Yamamoto, 2002). On the basis of the occurrence of ejecta deposits formed by impacting projectiles approaching the target from different incidence angles, ejecta planforms can be divided into five categories which range from near-vertical to low-angle incidence impact ( Figure 14): these are (a) symmetric, (b) offset, (c) offset and concentrated cross range, (d) forbidden zone, and (e) butterfly (Herrick & Forsberg-Taylor, 2003;Herrick & Hessen, 2006).…”

Section: Density Distribution As a Function Of Azimuthmentioning

confidence: 90%

“…The study of secondary craters also provides an approach to understand the nature of their parent impact crater. The spatial distribution of secondaries is representative of the ejecta distribution, from which the initial primary impact geometry, such as projectile approach azimuth and angle to the surface can be estimated (Anderson et al, 2003;Bottke et al, 2000;Davison et al, 2011;Gault & Wedekind, 1978;Herrick & Hessen, 2006;Pierazzo & Melosh, 2000;Schultz et al, 2007;Shuvalov, 2011;Yamamoto, 2002). In addition, the distinctive characteristics of secondary craters make them more readily recognizable than the thin and discontinuous ejecta deposits over broad distal areas.…”

Section: Introductionmentioning

confidence: 99%

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Lunar Orientale Impact Basin Secondary Craters: Spatial Distribution, Size‐Frequency Distribution, and Estimation of Fragment Size

et al. 2018

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Secondary impact craters, features created by projectiles ejected from a primary impact, contain important information about the primary cratering event and the nature and distribution of its ejecta. The Orientale impact basin (D ~ 930 km) is the youngest and the least degraded large impact basin on the Moon and has the most recognizable secondary impact craters. We identified and mapped 2,728 secondary craters in the investigated area of ~1.66 × 107 km2, covering an area from the rim of Orientale to six radii. Secondary crater diameters range from ~2 to 27 km, and the median diameter decreases as distance increases. Secondary craters are concentrated predominantly in the northwest and southwest. The ejecta deposit pattern inferred from secondary crater distribution suggests that the Orientale basin was formed by an oblique impact in which the downrange direction was 240°–265° in azimuth, and the incidence angle was steeper than 20°. The cumulative size‐frequency distribution of mapped secondary craters steepens as diameter increases and is very well approximated with a Weibull distribution with an exponent 1.32. A widely used crater scaling relationship predicts that the fragments that produced the secondary craters were predominantly in ~0.5–2‐km diameter range over the investigated area; the diameter of the largest fragment, however, decreases with increasing distance from Orientale. On the basis of the diameter of the largest secondary crater of Orientale, and other craters and basins, the largest secondary crater of the South Pole‐Aitken basin is estimated to be ~40 km in diameter. We explore the implications of these findings for the evolution of the megaregolith and future sample return missions.

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Section: Density Distribution As a Function Of Azimuthmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Lunar Orientale Impact Basin Secondary Craters: Spatial Distribution, Size‐Frequency Distribution, and Estimation of Fragment Size

et al. 2018

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“…However, neither their roles nor a mechanism to produce the secondary craters have been fully understood yet (e.g., Chapman and McKinnon, 1986). Advances in experimental studies of hyper-velocity impact (e.g., Gault and Wedekind, 1978;Yamamoto and Nakamura, 1997;Yamamoto, 2002) are necessary. As well, comparative tests in different regions, using high-resolution images that are expected from future lunar missions (Mizutani, 1995;Sasaki et al, 1999), are important.…”

Section: Examination Of the Secondary Crater Hypothesismentioning

confidence: 99%

Testing hypotheses for the origin of steep slope of lunar size-frequency distribution for small craters

Namiki

Honda

2014

Earth Planet Sp

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The crater size-frequency distribution of lunar maria is characterized by the change in slope of the population between 0.3 and 4 km in crater diameter. The origin of the steep segment in the distribution is not well understood. Nonetheless, craters smaller than a few km in diameter are widely used to estimate the crater retention age for areas so small that the number of larger craters is statistically insufficient. Future missions to the moon, which will obtain high resolution images, will provide a new, large data set of small craters. Thus it is important to review current hypotheses for their distributions before future missions are launched. We examine previous and new arguments and data bearing on the admixture of endogenic and secondary craters, horizontal heterogeneity of the substratum, and the size-frequency distribution of the primary production function. The endogenic crater and heterogeneous substratum hypotheses are seen to have little evidence in their favor, and can be eliminated. The primary production hypothesis fails to explain a wide variation of the size-frequency distribution of Apollo panoramic photographs. The secondary craters are likely the major source of the steepening of the distribution. It is ambiguous, however, which primary craters can produce sufficiently numerous secondary craters. The regional variation of the sizefrequency distributions shows that few large impacts produce enough secondary craters to affect the distributions in the surrounding area. We emphasize that a crater size-frequency distribution of small craters on the moon should not be taken as an indication of the surface age. More data obtained from future lunar missions should be viewed in this context, and continued to be examined for further insight into the possible formation mechanism for secondary craters.

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“…The studies involved both direct ejecta experiments and indirect collection of ejecta data acquired in course of impact experiments (e.g., [1e7]). The methods of the ejecta examination can be classified as follows: the snapshots of ejecta flows using high-speed cameras [6], the soft capturing of ejecta particles with low-density collectors [4,7,8], the use of different types of detectors including velocityemeters adopted for the registration of the flows of small-size particles [9], the use of aluminum and other higher density witnesses [3,5,10].…”

Section: Introductionmentioning

confidence: 99%

Properties of ejecta generated at high-velocity perforation of thin bumpers made from different constructional materials

Shumikhin

Myagkov

Bezrukov

2012

International Journal of Impact Engineering

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Measurement of Impact Ejecta from Regolith Targets in Oblique Impacts

Cited by 21 publications

References 24 publications

Lunar Orientale Impact Basin Secondary Craters: Spatial Distribution, Size‐Frequency Distribution, and Estimation of Fragment Size

Lunar Orientale Impact Basin Secondary Craters: Spatial Distribution, Size‐Frequency Distribution, and Estimation of Fragment Size

Testing hypotheses for the origin of steep slope of lunar size-frequency distribution for small craters

Properties of ejecta generated at high-velocity perforation of thin bumpers made from different constructional materials

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