Elsevier

Icarus

Volume 140, Issue 2, August 1999, Pages 379-407
Icarus

Regular Article
Mainbelt Asteroids: Results of Arecibo and Goldstone Radar Observations of 37 Objects during 1980–1995

https://doi.org/10.1006/icar.1999.6130Get rights and content

Abstract

We report detailed results of Arecibo and Goldstone radar observations of 30 mainbelt asteroids (MBAs) during 1980–1995. In addition to estimates of radar cross section, radar albedo, and circular polarization ratio, we obtain new constraints on pole direction for several asteroids, with those for 21 Lutetia being particularly restrictive. We carry out statistical analyses of disk-integrated properties (radar albedo and polarization ratio) of all 37 radar-observed MBAs. M asteroids seem to have higher radar albedos and a wider range of albedos than do asteroids from the other taxonomic classes; there is no evidence that C and S MBAs have different albedo distributions; and there is some suggestion, worthy of future study, that primitive B, F, G, and P asteroids are not as radar-bright as C and S objects. There is no statistically significant evidence that different taxonomic classes have different polarization ratio distributions, despite suggestions to the contrary based on visual inspection of these distributions. The similarity between the C and S albedo distributions implies similar near-surface regolith bulk densities. The hypothesis of ordinary chondritic composition for the S-class asteroids is reasonably consistent with the radar data, provided that these asteroids have typical lunar porosities. Nevertheless, it is possible that some of these targets have high-porosity regoliths of stony-iron composition. Our M-class sample presumably contains both metallic objects (such as 216 Kleopatra and, probably, 16 Psyche) and less metallic objects.

References (65)

  • D.L. Mitchell et al.

    Shape of Asteroid 433 Eros from inversion of Goldstone radar Doppler spectra

    Icarus

    (1998)
  • D.L. Mitchell et al.

    Radar observations of Asteroids 1 Ceres, 2 Pallas, and 4 Vesta

    Icarus

    (1996)
  • D.L. Mitchell et al.

    Radar observations of Asteroids 7 Iris, 9 Metis, 12 Victoria, 216 Kleopatra, and 654 Zelinda

    Icarus

    (1995)
  • S.J. Ostro et al.

    The shape of Eros

    Icarus

    (1990)
  • A.S. Rivkin et al.

    Three-micron spectrophotometric survey of M-and E-class asteroids

    Icarus

    (1995)
  • F. Scaltriti et al.

    The rotations of 128 Nemesis and 393 Lampetia: The longest known periods to date

    Icarus

    (1979)
  • S.J. Weidenschilling et al.

    Photometric geodesy of main-belt asteroids. III. Additional lightcurves

    Icarus

    (1990)
  • Bell, J. F., D. R. Davis, W. K. Hartmann, and M. J. Gaffey1989. Asteroids: The big picture. In Asteroids IIR. P....
  • M.J.S. Belton

    Bulk density of Asteroid 243 Ida from the orbit of its satellite Dactyl

    Nature

    (1995)
  • Bowell, E., T. Gehrels, and B. Zellner1979. Magnitudes, colors, types and adopted diameters of the asteroids. In...
  • R.H. Brown

    Ellipsoidal geometry in asteroid thermal models: The standard radiometric model

    Icarus

    (1985)
  • Chapman, C. R., and B. Zellner1978. The role of Earth-based observations of asteroids during the next decade. In...
  • W.J. Conover

    Practical Nonparametric Statistics

    (1980)
  • W.W. Daniel

    Applied Nonparametric Statistics

    (1990)
  • I. de Pater et al.

    Radar aperture synthesis observations of asteroids

    Icarus

    (1994)
  • Dollfus, A., M. Wolff, J. E. Geake, D. F. Lupishko, and L. M. Dougherty1989. Photopolarimetry of asteroids. In...
  • E. Dotto et al.

    M-type asteroids: Rotational properties of 16 objects

    Astron. Astrophys. Suppl. Ser.

    (1992)
  • D.W. Dunham

    Recent results from asteroidal occultations

    Occultation Newslett.

    (1997)
  • B. Efron et al.

    An Introduction to the Bootstrap

    (1993)
  • Gaffey, M. J., J. F. Bell, and D. P. Cruikshank1989. Reflectance spectroscopy and asteroid surface mineralogy. In...
  • J.B. Garvin et al.

    Venus global radar reflectivity and correlations with elevation

    J. Geophys. Res.

    (1985)
  • Gehrels, T.1970. Photometry of asteroids. In Surfaces and Interiors of Planets and SatellitesA. Dollfus, Ed., pp....
  • Cited by (85)

    • A brief history of spacecraft missions to asteroids and protoplanets

      2018, Primitive Meteorites and Asteroids: Physical, Chemical, and Spectroscopic Observations Paving the Way to Exploration
    • Iron and Stony-Iron Meteorites

      2013, Treatise on Geochemistry: Second Edition
    • Asteroids

      2013, Treatise on Geochemistry: Second Edition
    View all citing articles on Scopus
    View full text