Abstract
We investigate the flux of main-belt asteroid fragments into resonant orbits converting them into near-Earth asteroids (NEAs), and the variability of this flux due to chance interasteroidal collisions. A numerical model is used, based on collisional physics consistent with the results of laboratory impact experiments. The assumed main-belt asteroid size distribution is derived from that of known asteroids extrapolated down to sizes of ≈ 40 cm, modified in such a way to yield a quasi-stationary fragment production rate over times ≈ 100 Myr. The results show that the asteroid belt can supply a few hundred km-sized NEAs per year, well enough to sustain the current population of such bodies. On the other hand, if our collisional physics is correct, the number of existing 10-km objects implies that these objects either have very long-lived orbits, or must come from a different source (i.e., comets). Our model predicts that the fragments supplied from the asteroid belt have initially a power-law size distribution somewhat steeper than the observed one, suggesting preferential removal of small objects. The component of the NEA population with dynamical lifetimes shorter than or of the order of 1 Myr can vary by a factor reaching up to a few tens, due to single large-scale collisions in the main belt; these fluctuations are enhanced for smaller bodies and faster evolutionary time scales. As a consequence, the Earth's cratering rate can also change by about an order of magnitude over the 0.1 to 1 Myr time scales. Despite these sporadic spikes, when averaged over times of 10 Myr or longer the fluctuations are unlikely to exceed a factor two.
Article PDF
Similar content being viewed by others
References
Benoit, P.H. and Sears, D.W.G.: 1993, Breakup and structure of an H-chondrite parent body: The H-chondrite flux over the last million years, Icarus 101, pp. 188–200.
Bottke, W.F., Nolan, M.C., Greenberg, R. and Kolvoord, R.A.: 1994, Collisional life-times and impact statistics of near-Earth astereoids, in Hazards Due to Comets and Asteroids, Univ. of Arizona Press, Tucson, in press.
Campo Bagatin, A.: 1993, Thesis, Pisa University (unpublished).
Campo Bagatin, A., Farinella, P. and Petit, J.-M.: 1994a, Fragment ejection velocities and the collisional evolution of asteroids, Planet. Space Sci., in press.
Campo Bagatin, A., Cellino, A., Davis, D.R., Farinella, P. and Paolicchi, P.: 1994b, Wavy size distributions for collisional systems with a small-size cutoff, Planet. Space Sci., in press.
Cellino, A., Zappalà, V. and Farinella, P.: 1991, The asteroid size distribution from IRAS data, Mon. Not. R. astr. Soc. 253, 561–574.
Davis, D.R., Chapman, C.R., Weidenschilling, S.J. and Greenberg, R.: 1985, Collisional history of asteroids: Evidence from Vesta and the Hirayama families, Icarus 62, 30–53.
Davis, D.R., Farinella, P., Paolicchi, P., Weidenschilling, S.J. and Binzel, R.P.: 1989, Asteroid collisional history: Effects on sizes and spins, in Asteroids II (T. Gehrels, Ed.), pp. 805–826, Univ. of Arizona Press, Tucson.
Davis, D.R., Ryan, E.V. and Farinella, P.: 1994, Asteroid collisional evolution: Results from current scaling algorithms, Planet. Space Sci., in press.
Dohnanyi, J.W.: 1969, Collisional model of Asteroids and their debris, J. Geophys. Res. 74, 2531–2554.
Farinella, P. and Davis, D.R.: 1992, Collision rates and impact velocities in the main asteroid belt, Icarus 97, 111–123.
Farinella, P. and Davis, D.R.: 1994, Will the real asteroid size distribution please step forward?, Lunar and Planetary Science XXV, Part 1, 365–366.
Farinella, P., Davis, D.R., Cellino, A. and Zappalà, V.: 1992a, The collisional lifetime of asteroid 951 Gaspra, Astron. Astrophys. 257, 329–330.
Farinella, P., Davis, D.R., Paolicchi, P., Cellino, A. and Zappalà, V.: 1992b, Asteroid collisional evolution: An integrated model for the evolution of asteroid rotation rates, Astron. Astrophys. 253, 604–614.
Farinella, P., R. Gonczi, Ch. Froeschlé, and C. Froeschlé: 1993a, The injection of asteroid fragments into resonances, Icarus 101, 174–187.
Farinella, P., Froeschlé, Ch. and Gonczi, R.: 1993b, Meteorites from the asteroid 6 Hebe, Celest. Mech. 56, 287–305.
Farinella, P., Froeschlé, C. and Gonczi, R.: 1994a, Meteorite delivery and transport, in Asteroids, Comets, Meteors 1993 (A. Milani, M. Di Martino & A. Cellino, eds.), Proc. IAU Symp. 160, pp. 205–222, Kluwer, Dordrecht.
Farinella, P., Froeschlé, Ch., Froeschlé, C., Gonczi, R., Hahn, G., Morbidelli, A. and Valsecchi, G.B.: 1994b, Asteroids falling into the Sun, Nature 371, 314–317.
Froeschlé, Ch., Hahn, G., Gonczi, R., Morbidelli, A. and Farinella, P.: 1995, ‘Secular resonances and the dynamics of Mars-crossing and near-Earth asteroids’, In preparation.
Giblin, I., Martelli, G., Smith, P.N., Cellino, A., Di Martino, M., Zappalá, V., Farinella, P. and Paolicchi, P.: 1994, Field fragmentation of macroscopic targets simulating asteroidal catastrophic collisions, Icarus 110, 203–224.
Hahn, G., Lagerkvist, C.-I., Lindgren, M. and Dahlgren, M.: 1991, Orbital evolution studies of asteroids near the 5/2 mean motion resonance with Jupiter, Astron. Astrophys. 246, 603–618.
McFadden, L.-A., Tholen, D.J. and Veeder, G.J.: 1989, Physical properties of Aten, Apollo and Amor Asteroids, in Asteroids II (T. Gehrels, Ed.), pp. 442–467, Univ. of Arizona Press, Tucson.
Michel, P., Froeschlé, Ch. and Farinella, P.: 1994, ‘Dynamical evolution of NEAs: Close encounters, secular perturbations and resonances’, this volume.
Milani, A., Carpino, M., Hahn, G. and Nobili, A.M.: 1989, Dynamics of planet-crossing asteroids: Classes of orbital behavior — Project SPACEGUARD, Icarus 78, 212–269.
Morbidelli, A., Gonczi, R., Froeschlé, Ch. and P. Farinella, P.: 1994, Delivery of meteorites through the v 6 secular resonance, Astron. Astrophys. 282, 955–979.
Paolicchi, P.: 1994, Rushing to equilibrium: A simple model for the collisional evolution of asteroids, Planet. Space. Sci. 42(3), 207–212.
Petit, J.-M. and Farinella, P.: 1993, Modelling the outcomes of high-velocity impacts between small solar system bodies, Celest. Mech. 57, 1–28.
Valsecchi, G.B., Morbidelli, A., Gonczi, R., Farinella, P., Froeschlé, Ch. and Froeschlé, C.: 1994, Dynamical evolution of objects in orbits resembling that of P/Encke, Icarus, submitted.
Wetherill, G.W.: 1967, Collisions in the asteroid belt, J. Geophys. Res. 72, 2429–2444.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Menichella, M., Paolicchi, P. & Farinella, P. The main belt as a source of near-Earth asteroids. Earth Moon Planet 72, 133–149 (1996). https://doi.org/10.1007/BF00117512
Issue Date:
DOI: https://doi.org/10.1007/BF00117512