Passive microwave observations of asteroidsThe advances made since 1979 in the quantity and quality of the radio observations of asteroids and in the understanding of the physics of asteroidal microwave emission are reviewed. Radio continuum spectra analyses are now available for the four largest asteroids (Ceres, Vesta, Pallas, and Hygiea) at several wavelengths and several smaller asteroids (including Interamnia and Eunomia) at one wavelength. The spectra show that most asteroids are covered by a layer of material with physical properties of finely divided dust. This surface material is in layers of variable depth and has dielectric properties which vary from asteroid to asteroid. The effect of instrumentation on the interpretation of microwave observations is examined.
Document ID
19900039957
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Webster, William J., Jr. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Johnston, Kenneth J. (U.S. Navy, E. O. Hulburt Center for Space Research, Washington DC, United States)