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PHOTO CAPTION                                 Toutatis rotation
                                              P-46256
                                              October 5, 1995
     
These images show a computer model of the Earth-crossing asteroid 
4179 Toutatis. The model was created by Drs. Scott Hudson of 
Washington State University and Steven Ostro of NASA's Jet 
Propulsion Laboratory, using radar data that had been obtained 
with the Goldstone radar telescope in California and the Arecibo 
radar telescope in Puerto Rico. The object is about 4.6 
kilometers (3 miles) long. The resolution of the computer model 
is about 84 meters (275 feet). The views of the asteroid show 
shallow craters, linear ridges and a deep topographic "neck" 
whose geologic origin is not known. It may have been sculpted by 
impacts into a single, coherent body, or Toutatis might actually 
consist of two separate objects that came together in a gentle 
collision. Toutatis has one of the strangest rotation states yet 
observed in the solar system. Instead of spinning about a single 
axis as do the planets and the vast majority of asteroids, it 
"tumbles" somewhat like a football after a botched pass. Its 
rotation is the result of two different types of motion with 
periods of 5.4 and 7.3 Earth days that combine in such a way that 
Toutatis' orientation with respect to the solar system never 
repeats itself. Hudson and Ostro's model appeared in the October 
6, 1995 issue of Science. Their work was part of the Planetary 
Geology and Geophysics program and the Planetary Astronomy 
program within NASA's Office of Space Science, Washington, D.C.

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