George H. Diller
Kennedy Space Center                   June 13, 1997
407/867-2468

KSC Release No. 89-97

ACE SPACECRAFT ARRIVES AT KSC TO BE PREPARED FOR LAUNCH

NASA's Advanced Composition Explorer (ACE), to be launched aboard a
McDonnell Douglas Delta II rocket in August, arrived today at the
Kennedy Space Center (KSC) to begin prelaunch processing.  The
spacecraft, built for NASA by the Johns Hopkins University Applied
Physics Laboratory, was shipped by truck from the Goddard Space Flight
Center in Greenbelt, Md., yesterday.

ACE is a spin-stabilized spacecraft having a combination of nine sensors
and instruments.  Spinning at five revolutions per minute, it will
investigate the origin and evolution of solar phenomenon, the formation
of the solar corona, solar flares and the acceleration of the solar
wind.  The spacecraft will orbit the Libration Point, a location 900,000
miles from Earth where the gravitational effects of the Sun and Earth
are balanced.  ACE will be able to give scientists information about the
effect of the Sun on the near-Earth environment, as well as
interplanetary space while also providing clues about the lifestyle of
similar stars.

There are also two secondary investigations on the satellite itself.
The Real Time Solar Wind Monitor for the National Oceanic and
Atmospheric Administration (NOAA) will provide continuous "space
weather" information that can give limited advance warning of
geomagnetic storms. The Spacecraft Loads and Acoustics Monitor for the
Goddard Space Flight Center is a research and development payload which
will monitor the sound characteristics a spacecraft experiences within
the rocket's nose fairing environment during launch.

The ACE spacecraft will undergo final experiment integration and
functional testing at the Spacecraft Assembly and Encapsulation
Facility-2 (SAEF-2) located in the KSC Industrial Area.   The solar
arrays and magnetometer booms will be deployed and tested.  The
communications systems of the spacecraft will also be checked out which
will include a compatibility test with the Deep Space Network.  Finally,
the propulsion system tanks will be fueled and the spacecraft will be
spin tested.  About ten days before launch, ACE will be transported to
Space Launch Complex 17 and erected atop a Delta II 7920-8, a two-stage
rocket manufactured by McDonnell Douglas.

The buildup of the Delta vehicle on Pad 17-A is scheduled to be
performed the week of July 21.  This will include the erection of the
first and second stages and attachment of the nine strap-on solid rocket
boosters.  Atop the launch vehicle, the nose fairing is to be installed
around the spacecraft four days before launch.

Launch of Delta II/ACE is scheduled for Thursday, Aug. 21 at the opening
of a launch window which extends from 10:53:38 - 11:18:38 a.m. EDT, a
duration of 25 minutes.