Sarah Keegan
Headquarters, Washington, D.C.                    August 10, 1988

Ed Medal
Marshall Space Flight Center, Huntsville, Ala.


RELEASE:  88-113

LAST SHUTTLE MOTOR TEST SCHEDULED PRIOR TO DISCOVERY LAUNCH


     The fifth and final test firing of NASA's redesigned Space 
Shuttle solid rocket motor, prior to resumption of Shuttle 
flights, is scheduled for 1 p.m. MDT Thurs., Aug. 18, at Morton 
Thiokol's Space Operations facility near Brigham City, Utah.

     The 126-foot-long, 1.2-million-pound motor, designated 
Production Verification Motor-1 (PVM-1), will undergo a full 
duration, horizontal test firing of 2 minutes.  The motor will be 
extensively flawed to demonstrate the fail-safe characteristics 
of the redesign.

     The verification and qualification test program to certify 
the motor redesign consists of six full-duration.  One more full-
duration test will be conducted after Shuttle flights resume.  
That test, designated Qualification Motor-8, will be a cold-
weather motor firing planned for late December.

     Morton Thiokol is NASA's prime contractor for the solid 
rocket motor, and the Marshall Space Flight Center, Huntsville, 
Ala., manages the motor program for NASA.



	PVM-1 FACT SHEET


     PVM-1 is a full-scale, Space Shuttle solid rocket motor, 
approximately 126-feet long and 12 feet in diameter.  The motor 
weighs 1.2 million pounds, including 1.1 million pounds of 
propellant.  

     The three field joints, connecting the motor, segments are 
of the flight configuration, capture feature tang and clevis 
design with three Viton (TM) o-rings.  The mating insulation 
surfaces at each field joint are bonded with an adhesive and 
include a J-shaped deflection relief slot which reduces stresses 
and increases the sealing action of the bonded surfaces under 
motor pressure.  Heaters, mounted around the motor case at each 
field joint location, are thermostatically controlled to maintain 
joint temperature at a minimum of 75 degrees F.

     The motor case-to-nozzle joint on PVM-1 is the flight 
configuration which incorporates 100 radial bolts, adhesively 
bonded insulation surfaces, a shaped relief slot and an added 
Viton "wiper" o-ring designed to keep the adhesive away from the 
primary o-ring and on the insulation surfaces during assembly.

     The PVM-1 motor is fitted with nearly 400 instruments to 
measure acceleration, pressure, deflection, thrust, strain, 
temperature, electrical properties and other conditions.

     The deliberate flaws incorporated into the PVM-1 motor 
include:

     IGNITER-TO-CASE-JOINT:  There are two 5" by 0.4" artificial 
edge separations (unbonds) in the motor forward dome insulation 
where the igniter is bolted into the motor.  At the same 
locations, there are deliberate 1" gaps in the zinc chromate 
putty packed between the igniter body and case insulation.

     FORWARD FIELD JOINT:  There are no intentional flaws 
incorporated into this joint.

     CENTER FIELD JOINT:  There is a 0.125" by 0.05" channel-type 
flaw cut into the J-seal bonded insulation to assure pressure as 
far as the capture feature o-ring.  In addition, there is a 10" 
by 1.7" area of artificial edge separation in the case clevis 
insulation located 1.5" counterclockwise from the pressure-
assuring flaw; plus a 5" by 0.175" artificial edge separation in 
the case tang at the end of the capture feature located 1.5" 
clockwise from the pressure-assuring flaw.

     AFT FIELD JOINT:  There is a 0.5" by 0.1" channel-type flaw 
cut into the J-seal bonded insulation which is in turn aligned 
with a flawed capture feature o-ring.  The two flaws will assure 
pressure as far as the primary o-ring.

     CASE-TO-NOZZLE JOINT:  There is an hourglass-shaped 0.125" 
by 0.05" minimum area blowhole-type flaw cut through the 
polysulfide adhesive which, in turn, is aligned with a flawed 
wiper o-ring.  The two flaws will assure pressure as far as the 
primary o-ring.  In addition, there are two 10" by 0.40" areas of 
edge separations in the case insulation located 30" from and on 
either side of the pressure-assuring flaw.

	NOZZLE INTERNAL JOINT #5:  There is a 9" by 0.087" intentional 
void in the room temperature vulcanizing rubber sealant 
incorporated in this joint which will assure pressure from the 
flexible boot cavity to reach the primary o-ring.