A full-scale Space Shuttle Reusable Solid Rocket Motor is scheduled to test
fire for 123.2 seconds Thursday, May 24, at a Utah test facility.

The test, in Promontory, Utah, at Thiokol Propulsion, an Alliant
Techsystems, Inc., company, will be used to qualify a new insulation design
on the motor’s nozzle to case joint that will improve flight safety and help
reduce costs on the motor.

The Reusable Solid Rocket Motor Project Office at NASA’s Marshall Space
Flight Center in Huntsville, Ala., tests Flight Support Motors annually to
qualify any proposed upgrades or changes to the motor. The static – or
stationary — test is part of Shuttle’s ongoing verification of components,
materials and manufacturing processes required by the Marshall Center, which
oversees the Reusable Solid Rocket Motor project.

Support motors are used to evaluate, validate and qualify changes proposed
for the Shuttle’s Reusable Solid Rocket Motor. On this motor, there are 93
objectives and a total of 576 instrumentation channels being tested. The
two-minute test duration is the same length of time that the motors perform
during Shuttle flights.

“Full-scale static testing is a key element in our program, providing
valuable information on design, process and material changes,” said Mike
Rudolphi, manager of the Reusable Solid Rocket Motor Project Office. “The
rule is: Everything we fly, we static test first.”

There are four major certification objectives for the test of Flight Support
Motor-9. One of the more important tests is a change in insulation design
on the nozzle-to-case joint J-leg. The proposed design change improves the
thermal barrier protecting the O-rings on the motor by eliminating
polysulfide, a putty-like material applied to the joint surface as the motor
is assembled.

During assembly, polysulfide can trap air which may work its way through the
putty-like material exposing the thermal barrier to motor combustion gases.
The new design incorporates a J-joint – a joint shaped like a J – made of
rubber for a better seal and a carbon fiber braided rope. Essentially, it is
designed so that as the motor pressure increases, the seal tightens; a
proven design used in the case field joints.

The rope, which is downstream of the J-joint, is another safety addition
because it absorbs heat should gas seep past the joint. Basically, the new
design enhances the primary thermal barrier and adds another thermal barrier
with the rope.

The J-joint design should be easier to install and inspect during assembly,
require less technical maintenance, and therefore cost less. The upgrade is
slated to fly in late 2004.

The firing also will retest a new adhesive that bonds metal parts to
phenolic parts in the nozzle; new environmentally-friendly solvents; and
demonstrate a new nozzle ablative insulation for the motor.

At 126 feet (38.4 meters) long and 12 feet (3.6 meters) in diameter, the
Shuttle’s Reusable Solid Rocket Motor is the largest solid rocket motor ever
flown and the first designed for reuse. During its two-minute burn at
liftoff, each motor generates an average thrust of 2.6 million pounds (1.2
million kilograms).
The test will be conducted in the T-97 bay of the Thiokol test facility,
located north of Salt Lake City. Following the test, the data will be
analyzed and the results for each objective provided in a final report. The
metal case segments and nozzle components will be refurbished for reuse.

The Marshall Center is NASA’s lead center for development of space
transportation and propulsion systems and advanced large optics
manufacturing technology, as well as microgravity research — scientific
research in the unique low-gravity environment inside the International
Space Station and other spacecraft.

NOTE TO EDITORS / NEWS DIRECTORS: A special viewing area will be provided
at Thiokol’s Utah test facility for the news media. To attend the firing,
media representatives must register with Melodie deGuibert of Thiokol by
telephoning (435) 863-3169 no later than 10 a.m. MDT Wednesday, May 23.