OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY 
CALIFORNIA INSTITUTE OF TECHNOLOGY 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
PASADENA, CALIFORNIA 91109. TELEPHONE (2l3) 354-5011 
  
PHOTO CAPTION                                      Voyager 1-94 
                                                   P-21227C
                                                   March 6, 1979 
  
This picture of Io, the innermost Galilean satellite, was taken
by Voyager 1 on the morning of March 5, 1979 at a range of
377,000 kilometers (226,200 miles). The smallest features visible
are about 10 kilometers (6 miles) across. The reddish, white
and black areas are probably surface deposits, possibly consisting
of mixtures of salts, sulfur and sublimate deposits of possible
volcanic origin. Many of the black spots in these pictures are
associated with craters of possible volcanic origin. The lack
of impact craters on Io suggests that the surface is relatively
young compared to the other Galilean satellites and some of the
terrestrial planets such as Mercury and the Moon. JPL manages
and controls the Voyager Project for NASA's Office of Space
Science.
  
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