Calculation of meteoroid impacts on moon and earth

Bandermann, L. W.; Singer, S. Fred

doi:10.1016/0019-1035(73)90142-5

Cited by 30 publications

(22 citation statements)

References 6 publications

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“…This concept has been numerically investigated by Wood (1973);Le Feuvre and Wieczorek (2005) and deemed plausible, though an analytic calculation by Bandermann and Singer (1973) showed the amplitude of the asymmetry depends on the Earth-Moon distance and the velocity of the incoming projectiles.…”

Section: Introductionmentioning

confidence: 99%

Current bombardment of the Earth–Moon system: Emphasis on cratering asymmetries

Gallant

Gladman

Ćuk

2009

Icarus

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We calculate the current spatial distribution of projectile delivery to the Earth and Moon using numerical orbital dynamics simulations of candidate impactors drawn from a debiased Near-EarthObject (NEO) model. Surprisingly, we find that the average lunar impact velocity is 20 km/s, which has ramifications in converting observed crater densities to impactor size distributions. We determine that current crater production on the leading hemisphere of the Moon is 1.29 ± 0.01 that of the trailing when considering the ratio of craters within 30 • of the apex to those within 30 • of the antapex and that there is virtually no nearside-farside asymmetry. As expected, the degree of leading-trailing asymmetry increases when the Moon's orbital distance is decreased. We examine the latitude distribution of impactor sites and find that for both the Earth and Moon there is a small deficiency of time-averaged impact rates at the poles. The ratio between deliveries within 30 • of the pole to that of a 30 • band centered on the equator is nearly unity for Earth (< 1%)(0.992 ± 0.001) but detectably non-uniform for the Moon (∼ 10%) (0.912 ± 0.004). The terrestrial arrival results are examined to determine the degree of AM/PM asymmetry to compare with meteorite fall times (of which there seems to be a PM excess). Our results show that the impact flux of objects derived from the NEOs in the AM hours is ∼ 2 times that of the PM hemisphere, further supporting the assertion that meteorite-dropping objects are recent ejections from the main asteroid belt rather than young fragments of NEOs.

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Section: Introductionmentioning

confidence: 99%

Current bombardment of the Earth–Moon system: Emphasis on cratering asymmetries

Gallant

Gladman

Ćuk

2009

Icarus

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“…The ratio of influx rates for the Earth and Moon is influenced by the Earth-Moon distance, and particularly by the geocentric velocity of the incoming body at infinity (Bandermann and Singer, 1973). Bills and Ray (1 999) recently summarized the evolution of the lunar orbit.…”

Section: Relative Influx To Earth and Moonmentioning

confidence: 99%

“…The record of these basin-forming impacts is contained in the ancient lunar breccias collected at all lunar highland sites. All but one of these basinsOrientale-formed by -3.8 Ga. Because the Moon was formed in situ (Benz and Cameron, 1990;Cameron, 1997), the Moon and Earth may have sampled the same population of objects (Hartmann, 1976), with the Earth getting the lion's share (Bandermann and Singer, 1973;Chyba, 199 1). Occasionally it has been asked why there was no late influx of siderophiles to the Moon (Taylor and Esat, 1996).…”

Section: Introductionmentioning

confidence: 99%

Siderophile elements in Earth's upper mantle and lunar breccias: Data synthesis suggests manifestations of the same late influx

Morgan

Walker

Brandon

et al. 2001

Meteorit & Planetary Scien

124

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Abstract-The platinum group elements (PGE; Ru, Rh, Pd, Os, Ir, Pt), Re and Au comprise the highly siderophile elements (HSE). We reexamine selected isotopic and abundance data sets for HSE in upper mantle peridotites to resolve a longstanding dichotomy. Re-0s and Pt-0s isotope systematics, and approximately chondritic proportions of PGE in these rocks, suggest the presence in undepleted mantle of a chondrite-like component, which is parsimoniously explained by late influx of large planetisimals after formation of the Earth's core and the Moon. But some suites of xenolithic and orogenic spinel lherzolites, and abyssal peridotites, have a CI-normalized PGE pattern with enhanced Pd that is sometimes termed "non-chondritic". We find that this observation is consistent with other evidence of a late influx of material more closely resembling enstatite, rather than ordinary or carbonaceous, chondrites. Regional variations in HSE patterns may be a consequence of a late influx of very large objects of variable composition.Studies of many ancient (>3.8 Ga) lunar breccias show regional variations in A d I r and suggest that "graininess" existed during the early bombardment of the Earth and Moon. Reliable Pd values are available only for Apollo 17 breccias 73215 and 73255, however. Differences in HSE patterns between the aphanitic and anorthositic lithologies in these breccias show fractionation between a refractory group (Re, 0 s and Ir) and a normal (Pd, Ni, and Au) group and may reflect the compositions of the impacting bodies. Similar fractionation is apparent between the EH and EL chondrites, whose PGE patterns resemble those of the aphanitic and anorthositic lithologies, respectively.The striking resemblance of HSE and chalcogen (S, Se) patterns in the Apollo aphanites and highPd terrestrial peridotites suggest that the "non-chondritic" abundance ratios in the latter may be reflected in the composition of planetisimals striking the Moon in the first 700 Ma of Earth-Moon history. Most notably, high Pd may be part of a general enhancement of HSE more volatile than Fe suggesting that the Au abundance in at least parts of the upper mantle may be 1.5 to 2x higher than previously estimated.The early lunar influx may be estimated from observed basin-sized craters. Comparison of relative influx to Earth and Moon suggests that the enrichment of HSE is limited to the upper mantle above 670 km. To infer enrichment of the whole mantle would require several large lunar impacts not yet identified.

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“…Even though the lunaites are of unknown provenance, they can, as a population, be used for this purpose. Launch locations of lunaites may be slightly biased toward the Moon's orbit-leading (western) hemisphere (Wiesel 1971;Bandermann and Singer 1973;Pinet 1985). To the extent they are, they will be biased toward high Th (according to Lawrence et al [2003], about 80% of the The homogeneous site data manifest a significant offset of ∼0.7 µg/g in the x-axis intercept.…”

Section: Lunaites and The Global Regolith Th Spectrummentioning

confidence: 99%