Paula Cleggett-Haleim
Headquarters, Washington, D.C.                                                                   
June 28, 1991
(Phone:  202/453-1547)

Jim Wilson
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone:  818/354-5011)


RELEASE:  91-99

GALILEO TO SET COURSE FOR ENCOUNTER WITH ASTEROID GASPRA


   NASA's Galileo spacecraft will turn and fire its small 
on-board thrusters Tuesday, July 2, 1991, to set its course for 
an encounter with the asteroid Gaspra in October 1991.  Acting on 
computer commands sent to it by engineers at the Jet Propulsion 
Laboratory (JPL), the 2-1/2-ton spacecraft will begin its 
maneuver about 11 a.m. EDT.  

   The maneuver will alter Galileo's velocity in space by about 
8 miles per hour, slowing it slightly and adjusting the flyby 
distance at Gaspra on Oct. 29, 1991, to 1,000 miles.

   The October event will be the first flyby of an asteroid.  
Gaspra, about 8 miles across, orbits roughly 200 million miles 
from the sun near the inner edge of the asteroid belt.  
Scientists believe it is a fairly typical, small, rocky main-belt 
asteroid.

   Galileo is enroute to Jupiter, where it will go into orbit in 
December 1995 after sending a probe into Jupiter's atmosphere.  
Following an October 1989 launch, the spacecraft flew by Venus 
and the Earth in 1990 in gravity-assist passes to increase the 
spacecraft's velocity.  One more Earth gravity assist is planned 
in December 1992 to pick up the last increment of velocity 
necessary to reach Jupiter.

   The Galileo mission is managed for NASA's Office of Space 
Science and Applications by JPL.

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