Radar Imaging of Binary Near-Earth Asteroid (66391) 1999 KW4

  title={Radar Imaging of Binary Near-Earth Asteroid (66391) 1999 KW4},
  author={Steven Jeffrey Ostro and Jean-Luc Margot and Lance A. M. Benner and Jon D. Giorgini and Daniel J. Scheeres and Eugene Gregory Fahnestock and Stephen B. Broschart and J. Bellerose and Michael C. Nolan and Christopher Magri and Petr Pravec and Petr Scheirich and R. Lynn Rose and Raymond F. Jurgens and Eric M. De Jong and Shigeru Suzuki},
  pages={1276 - 1280}
High-resolution radar images reveal near-Earth asteroid (66391) 1999 KW4 to be a binary system. The ∼1.5-kilometer-diameter primary (Alpha) is an unconsolidated gravitational aggregate with a spin period ∼2.8 hours, bulk density ∼2 grams per cubic centimeter, porosity ∼50%, and an oblate shape dominated by an equatorial ridge at the object's potential-energy minimum. The ∼0.5-kilometer secondary (Beta) is elongated and probably is denser than Alpha. Its average orbit about Alpha is circular… Expand

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