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Volumn 298, Issue 5599, 2002, Pages 1752-1756

Martian meteorite launch: High-speed ejecta from small craters

Author keywords

[No Author keywords available]

Indexed keywords

COMPUTER SIMULATION; METEOR IMPACTS;

EID: 0037195630     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1077483     Document Type: Article
Times cited : (160)

References (41)
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    • R. Kallenbach, J. Geiss, W. K. Hartmann, Eds. (Kluwer, Netherlands)
    • B. A. Ivanov, in Chronology and Evolution of Mars, R. Kallenbach, J. Geiss, W. K. Hartmann, Eds. (Kluwer, Netherlands, 2001), pp. 87-104.
    • (2001) Chronology and Evolution of Mars , pp. 87-104
    • Ivanov, B.A.1
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    • -, J. Geophys. Res. 100, 5329 (1995).
    • (1995) J. Geophys. Res. , vol.100 , pp. 5329
  • 9
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    • 2242430083 scopus 로고    scopus 로고
    • note
    • eq increases with time, the regolith thickness increases with time. This theory has been validated against seismic studies of regolith thickness on the Moon. For a complete treatment, see (22).
  • 17
    • 24844457820 scopus 로고
    • J. N. Head, Eos 76, F336 (1995).
    • (1995) Eos , vol.76
    • Head, J.N.1
  • 18
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    • 2242486714 scopus 로고    scopus 로고
    • note
    • 2. Moreover, the propagation of the shock wave will still be affected by the physical nature of the medium (damaged versus undamaged). The azimuthal dependence of shock wave strength might modulate the number of ejected fragments from a crater of a given size, but it should not change our finding that the presence of an impact-generated regolith suppresses spall velocity and hence biases the ejecta launched from Mars in favor of young material.
  • 25
    • 0000697634 scopus 로고
    • H. H. Kieffer, B. M. Jakosky, C. W. Snyder, M. S. Matthews, Eds. (Univ. of Arizona Press, Tucson, AZ)
    • K. L. Tanaka, D. H. Scott, R. Greeley, in Mars, H. H. Kieffer, B. M. Jakosky, C. W. Snyder, M. S. Matthews, Eds. (Univ. of Arizona Press, Tucson, AZ, 1992), pp. 345-382.
    • (1992) Mars , pp. 345-382
    • Tanaka, K.L.1    Scott, D.H.2    Greeley, R.3
  • 26
    • 2242457905 scopus 로고    scopus 로고
    • note
    • 8 or 1/256 chance of all stones presenting a single-stage CRE history. Because multiple ages are required, and at each step the ratio of two-stage to single-stage CRE history material increases, the odds for recovering only 4-π exposed stones drops even more. Finally, an impact that launches a 20-m-diameter fragment will likely launch an enormous number of decimeter-scale fragments, which would be more likely to reach Earth than would pieces of the 20-m fragment (28).
  • 27
    • 2242475068 scopus 로고    scopus 로고
    • note
    • The data in Fig. 3 show that a low-velocity regolith layer may be irrelevant with regard to launching lunar meteorites because of the much lower lunar escape velocity of ∼2.3 km/s. At this value, the spall velocity is the same in our models regardless of the presence of a regolith layer. The launch efficiency is then the same whether the surface is pristine or a deep regolith. Hence, the mechanism by which the launch of martian meteorites is biased in favor of young material cannot operate on the Moon. One implication of this is that lunar meteorite petrology should be representative of the observed surface units. This appears to be the case (9). The delivery time scale is much less than for martian meteorites, and the maximum terrestrial age is evidently ∼0.1 Ma. This implies that meteorites found on Earth are predominately from the most recent lunar impacts, because samples from older impacts would have been destroyed long ago by the terrestrial environment. As a test of our model, we simulated lunar meteorite launch, modeling the lunar surface as basaltic covered by a regolith of the same material, but damaged. We found that the expected number of source craters is consistent with that estimated from the lunar meteorites in hand, but only for impacts that are recent compared to the Moon-to-Earth delivery time scale. Samples from older impacts appear to be greatly underrepresented in the meteorite collection with regard to our model results. The few lunar meteorites with launch ages greater than a few hundred thousand years (up to ∼10 Ma) are found only if they have been sequestered in the relatively benign space environment for most of their postlaunch history (29).
  • 41
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    • note
    • The authors acknowledge helpful reviews, which improved the quality of this paper.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.