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                               STS 51-G Mission
         The Orbiter Discovery lifted off from Pad A, Launch Complex 39,
   KSC, at 7:33 a.m. EDT on June 17, 1985.  The largest items of cargo were
three communications satellites.  Also flown were the deployable/retrievable
Spartan 1, six Getaway Special canisters, a High Precision Tracking  Experiment
(HPTE) for the Strategic Defense Initiative ("Star Wars"), a materials
processing furnace, and French biomedical experiments.
         All three communications satellites were successfully deployed
   and turned over to their owner-operators.  Their PAM-D perigee booster
motors fired and all three reached geosynchronous orbit, where they entered
checkout operations.  Spartan 1 was deployed and recovered.  All the
experiments were successfully accomplished. Discovery landed at Edwards AFB at
9:12 a.m. EDT on June 24, 1985, after a mission duration of 7 days, one hour
and 39 minutes.
. The crew members were Daniel C. Brandenstein, commander; John
   O. Creighton, pilot; Shannon W. Lucid, Steven R. Nagel, and John M. Fabian,
mission specialists; and Patrick Baudry, France, and Prince Sultan Salman
Al-Saud, Saudi Arabia, payload specialists. deployed were the Arabsat 1-B (Arab
Satellite Communications Organization); Morelos 1 (Mexico); and Telstar 3-D
(AT&T).  All three utilized PAM-D booster stages to achieve geosynchronous
transfer orbits after deployment from the Discovery.  The latter two spacecraft
are variants of the Hughes-built HS-376 series of spin- stabilized satellites.
Both use the Morton Thiokol Star 48 motor to circularize the orbit and align it
with the equator at apogee. Morelos 1 provides 12 channels operating in the
C-band and 6 channels operating in the Ku band.  It can provide educational and
commercial television programs, telephone and facsimile services, and data and
business transmission services to even the most remote parts of Mexico.
Telstar 3-D operates in the C-band only, and has 24 working channels.  Using
single sideband technology, a Telstar can relay up to 86,400 two-way telephone
calls.  Both spacecraft are about 22 ft high and 7 ft wide when deployed, and
have a mass of around l,450 lbs when operational.
         Arabsat 1 satellites are built by an international team led by
   Aerospatiale of France.  It is a three-axis stabilized spacecraft with two
deployable solar array wings, making it almost 68 ft long and over 18 ft wide
when deployed in orbit.  It weighs about 2,800 lbs in its initial orbit, but
some 1,490 lbs of this is propellant. It has an onboard low-thrust motor that
utilizes hydrazine and nitrogen tetroxide, and transfers from an initial
elliptical to geosynchronous orbit by firing this motor. The remaining
propellant is then used for station-keeping or moving over the life of the
satellite.
         Spartan 1 measured 126 by 42 by 48 inches, and weighed 2,223
   lbs.  The Spartan is a carrier, designed to be deployed from the orbiter and
fly free in space before being retrieved.  Spartan 1 included 300 lbs of
experiments in the field of astronomy.  It was deployed and operated
successfully, independent of the orbiter, before being retrieved.
         The materials furnace, French biomedical experiments, and six
   Getaway Special experiments were all successfully performed, although the
GO34 Getaway Special shut down prematurely.  The Strategic Defense Initiative
failed during its first try on orbit 37 because the orbiter was not at the
correct attitude.  It was successfully completed on orbit 64.
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