William M. Grundy

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Binaries have played a crucial role many times in the history of modern astronomy and are doing so again in the rapidly evolving exploration of the Kuiper Belt. The large fraction of transneptunian objects that are binary or multiple, 48 such systems are now known, has been an unanticipated windfall. Separations and relative magnitudes measured in discovery(More)
We present new astrometry of Pluto's three satellites from images taken of the Pluto system during 2002-3 with the High Resolution Camera (HRC) mode of the Advanced Camera for Surveys (ACS) instrument on the Hubble Space Telescope. The observations were designed to produce an albedo map of Pluto but they also contain images of Charon and the two recently(More)
We have searched 101 Classical transneptunian objects for companions with the Hubble Space Telescope. Of these, at least 21 are binary. The heliocentric inclinations of the objects we observed range from 0.6-34 •. We find a very strong anticorrelation of binaries with inclination. Of the 58 targets that have inclinations of less than 5.5 • , 17 are binary,(More)
A four-body orbit solution for the Pluto system yields GM values of 870. Assuming a Charon-like density of 1.63 gm cm −3 , the implied diameters for Nix and Hydra are 88 and 72 km, leading to visual geometric albedos of 0.08 and 0.18, respectively, though with considerable uncertainty. The eccentricity of Charon's orbit has a significant nonzero value;(More)
The near-infrared spectra of icy volatiles collected from planetary surfaces can be used to infer surface parameters, which in turn may depend on the recent geologic history. The high dimensionality and complexity of the spectral data, the subtle differences between the spectra, and the highly nonlinear interplay between surface parameters make it often(More)
The New Horizons spacecraft will achieve a wide range of measurement objectives at the Pluto system, including color and panchromatic maps, 1.25–2.50 micron spectral images for studying surface compositions, and measurements of Pluto's atmosphere (temperatures , composition, hazes, and the escape rate). Additional measurement objectives include topography,(More)
Near-Infrared reflectance spectra of planets can be used to infer surface parameters, sometimes with relevance to recent geologic history. Accurate prediction of parameters (such as composition, temperature , grain size, crystalline state, and dilution of one species within another) is often difficult because parameters manifest subtle but significant(More)
Introduction: The Panoramic Camera (Pancam) on the Opportunity Mars Exploration Rovers [1] acquired multispectral reflectance observations of outcrop rocks and spherule-rich soils at different incidence, emission, and phase angles (0-155°) that were used for photometric modeling to constrain the albedo and physical properties of the surface materials.(More)