Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-25T23:38:21.107Z Has data issue: false hasContentIssue false
  • English
  • Français

3. Fragmentation of Asteroids and Delivery of Fragments to Earth

Published online by Cambridge University Press:  12 April 2016

G. W. Wetherill

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Earth-impacting meteoroids are derived from both comets and asteroids, and some uncertainty still exists regarding with which of these bodies some stone meteorites should be identified. In contrast, the long cosmic ray exposure ages of iron meteorites strongly suggest a long-lived asteroidal source capable of providing ~108 g/yr of this material to the earth’s surface over at least much of solar system history. Spectrophotometric data show that differentiated asteroids are concentrated in the inner portion of the asteroid belt. The orbital histories of fragments of inner belt asteroids are investigated, considering the combined effects of close planetary encounters, secular perturbations, and secular resonances. Particular attention is given to the low inclination (<15°) objects with small semimajcr axis (2.1 to 2.6 A.U.), which can make fairly close approaches to Mars (<0.1 A.U.). It is found that the annual yield and dynamical lifetime of collision fragments of these asteroids is in agreement with the observed impact rate and exposure age of iron meteorites. A smaller yield of stone meteorites (-107 g/yr) is expected, because elimination of these objects by collision is probable on the long dynamical time scaTe. Achondrites could be produced in this way; the yield is probably too low to account for chondrites. Chondrites could possibly be derived indirectly from these bodies insofar as these asteroids are also sources of Apollo and Amor objects.

Type
Part V. Orbital Evolution and Fragmentation of Asteroids
Information
International Astronomical Union Colloquium , Volume 39: Comets, Asteroids, Meteorites: Interrelations, Evolution and Origins , December 1977 , pp. 283 - 291
Copyright
Copyright © A.H. Delsemme 1977

References

Anders, E. 1964, Space Science Rev., 3, 583.Google Scholar
Arnold, J. R. 1964, in Isotopic and Cosmic Chemistry, 347, North Holland.Google Scholar
Arnold, J. R. 1965, Astrophys. J., 141, 1536.Google Scholar
Brouwcr, D. 1951, Astron. J., 56, 9.Google Scholar
Brouwer, D., and VanWoerkora, A.J.J. 1950, Astron. Papers U.S. Naval Obs. Naut. Almanac Office 13, Part II, 85.Google Scholar
Ceplecha, Z. 1977, this volume.Google Scholar
Ceplecha, Z., and McCrosky, R. E. 1976, Center for Astrophysics, Preprint Series, No. 442.Google Scholar
Chapman, C. R. 1976, Geochim. Cosmochim. Acta, 40, 701.CrossRefGoogle Scholar
Gault, D. E., Shoemaker, E. M., and Moore, H. J. 1963, NASA TN 1767.Google Scholar
Levin, B. J. 1977, this volume.Google Scholar
Levin, B. J., Simonenko, A. N., and Anders, E. 1976, Icarus, in press.Google Scholar
Morrison, D. 1974, Astrophysics. J., 194, 203.Google Scholar
Morrison, D., and Chapman, C. R. 1976, Astrophys. J., 204, 934.Google Scholar
O’Keefe, J. D., and Ahrcns, T. J. 1976, Proc. 7th Lunar Sci. Conf., Pergamon, in press.Google Scholar
Öpik, E. J. 1951, Proc. Roy. Irish Acad., 54A, 165.Google Scholar
Scholl, J., and Froeschlé, C. 1976, this volume.Google Scholar
Simonenko, A. N. 1977, this volume.Google Scholar
Voshage, H. 1967, Z. Naturforsch, 22a, 477.Google Scholar
Wetherill, G. W. 1967, J. Geophys. Res., 72, 2429.CrossRefGoogle Scholar
Wetherill, G. W. 1968a, in Origin and Distribution of the Elements, Ahrens, L. H., ed., pp. 423–443, Pergamon, Oxford.Google Scholar
Wetherill, G. W. 1968b, Science, 159, 79.Google Scholar
Wetherill, G. W. 1969, in Meteorite Research, Millman, P., ed. pp. 573–589, Reidel, Dordrecht.Google Scholar
Wetherill, G. W. 1971, in Physical Studies of the Minor Planets, Gehrcls, T., ed. pp. 447–460, NASA SP-267.Google Scholar
Wetherill, G. W. 1974, Ann. Rev. Earth Planet. Sci., 2, 303.CrossRefGoogle Scholar
Wetherill, G. W. 1975, Proc. 6th Lunar Sci. Conf., Pergamon, 1539.Google Scholar
Wetherill, G. W. 1976, Geochim. Cosmochim. Acta, in press.Google Scholar
Wetherill, G. W., and Williams, J. C. 1968, J. Geophys. Res., 73, 635.CrossRefGoogle Scholar
Williams, J. G. 1969, Ph.D. dissertation, UCLA, 273 pp.Google Scholar
Williams, J. G. 1971, in Physical Studies of Minor Planets, Gehrels, T., Ed. pp. 177–181, NASA SP-267.Google Scholar
Zimmerman, P. D., and Wetherill, G. W. 1973, Science, 132, 51.Google Scholar