From: dnadams@nyx.cs.du.edu (Dean Adams)
Subject: Ariane V.54 / Galaxy VII
Apparently-To: sci-space-news@uunet.uu.net
Followup-To: sci.space
Organization: University of Denver, Dept. of Math & Comp. Sci.
Date: Tue, 13 Oct 1992 01:12:27 GMT

ARIANESPACE FLIGHT 54

The 54th Ariane launch is scheduled to place the Hughes Communications 
GALAXY VII satellite into a geostationary transfer orbit adapted for the
PVA (Perigee Velocity Augmentation) procedure, using an Ariane 42P launch
vehicle equipped with 2 solid strap-on boosters (PAP).  This will be the 
3rd flight of an Ariane 4 in the 42P configuration.  It will be launched 
from the Ariane launch complex ELA 2, in Kourou -- French Guiana.

The launch vehicle performance requirement for this mission is 3,043 kg 
(6,710 lb), of which 2,968 kg (6,545 lb) represents the satellite mass.
The total vehicle mass at liftoff is 323,161 kg.


Required Orbit Characteristics:
  Perigee Altitude ..... 200 km
  Apogee Altitude ...... 27,673 km at injection (prior to PVA)
  Inclination ..........   7 degrees


The Ariane 42P lift-off for Flight 54 is scheduled on Thursday October 15,
1992, as soon as possible within the following launch window:

     Kourou Time       GMT (10/16/92)    Washington, DC
     21:14 - 22:05     00:14 - 01:05     20:14 - 21:05


LAUNCH VEHICLE:

Ariane 42P.  This is a three-stage liquid fueled launcher with solid fueled 
strap-on boosters.  The first stage (L220) is built by Aerospatiale, and is 
powered by 4 liquid fueled Viking V engines.  The second stage (L33) is built
by MBB Erno and is powered by a single Viking IV engine.  Both the Viking IV
and V engines are manufactured by SEP.  The first and second stages use a 
biliquid UH25/N2O4 fuel.  The third stage is built by Aerospatiale and is 
the H10 "plus", with larger fuel tanks and increased performance over past
models.  It uses a cryogenic H2/O2 fueled HM-7B engine built by SEP. The two
strap-on boosters (PAP) are built by BPD and use a solid Flexadrine propellant.
The fully assembled launch vehicle stands 54.5 meters high on the pad.  
It uses the Ariane Short payload fairing.


Flight Profile:

 +01:31  Solid strap-on booster jettison
 +03:27  First stage separation
 +03:30  Second stage ignition
 +04:35  Fairing jettison
 +05:30  Second stage separation
 +05:43  Third stage ignition
 +18:11  Third stage shutdown / orbit injection
 +20:00  GALAXY VII separation
 +22:46  End of Ariane mission 52


Perigee Velocity Augmentation (PVA):

PVA is a procedure which optimizes the combined performance of launch 
vehicle and satellite to increase the on-orbit life of the satellite.
For this mission, the Ariane 42P will lift around 280 kg of additional
satellite propellants, to an apogee of 27,600 km instead of the GTO
apogee of 35,975.  The Galaxy VII satellite will use its apogee motor
at the 3rd and 6th perigee to raise the apogee to the altitude normally
used for circularization of the orbit.

The on-orbit life increase is due to the fact that the satellite apogee 
motor does not need to propel the dry Ariane 3rd, which will remain in
the lower orbit of 200 x 22,673 km.  This procedure can only be used by
satellites equipped with a liquid bi-propellant apogee motor (which can
be restarted), and whose tank capacity allows fuel in excess of that 
necessary for a standard GTO.  Due to the small inclination of the Ariane
mission (7 degrees), this capacity is often available when the satellites
are built to be launched from sites further away from the equator.  
This combination of HS-601/Ariane 42P/PVA allows an increase of more
than one year of orbital life for the commercial use of the satellite.


PAYLOAD:

Galaxy VII is the first satellite with a combined C-band and Ku-band
capability in the Galaxy fleet owned by Hughes Communications.  It is
also the first Arianespace launch of the type HS-601 three-axis stabilized
satellite manufactured by Hughes Aircraft Company.

  Total mass at lift-off .... 2,968 kg
  Mass at GEO insertion ..... 1,680 kg
  Dry mass .................. 1,303 kg     
  On-board power ............ 4,700 W (end of life)
  Nominal lifetime .......... 13.5 years     
  Span of solar panels ...... 26.5 m
  On-Orbit position ......... 91 degrees west, over the Galapagos Islands.

 Transmission capacity:  
   24/30 Ku-band transponders of 50W each.
   24/30 C-band transponders of 16W each.

 In-flight operations:
   Apogee motor ignition for PVA maneuver is at about 24 hrs after launch 
   at the 3rd perigee, and about 60 hrs after launch at the 6th perigee.

   First apogee motor firing is at the 12th apogee, about 5 days after 
   launch.  Further firing will be done at 14th and 15th apogee.

   Deployment of solar panels .... about 10 days after launch.


LAUNCH COVERAGE:

All Ariane missions are broadcast live via satellite from Kourou. Coverage
begins at 30 minutes before launch and continues until all payloads have 
been deployed.  This mission will likely be carried on Galaxy 6, however
it could end up being located on a different satellite such as Galaxy 2.


-{ Dean Adams }-

Newsgroups: sci.space.news