SRB firing in Utah a success

by Chris Bergin

ATK Thiokol Inc. has successfully tested their first Production Rate Motor during a two minute firing of a Solid Rocket Booster (SRB) in Promontory, north of Salt Lake City.

The firing is one of several annual tests conducted by MSFC (NASA’s Marshall Space Flight Center) – controlled by their Reusable Solid Rocket Motor Project Office to qualify any proposed changes to the rocket motor and to guarantee that new materials meet safety requirements.

The SRB firing closely replicates their actual performance in helping a Shuttle ‘uphill’ – with this test firing being used to check the performance of new sensors that are upgraded from those currently used by NASA. These solid propellant rockets take the Shuttle to an altitude of 28 miles at a speed of 3,094 mph before they separate and fall into the ocean to be retrieved, then refurbished and prepared for another flight.

The new sensors – called Intelligent Pressure Transducers – read and retain information at a much faster rate than the current electronics – noting pressures generated in the motor during an actual launch.

“Testing such as this is important to ensure continued quality and performance,” said Jody Singer, manager of the Reusable Solid Rocket Motor Project, MSFC.

The test was used to satisfied 48 objectives, including the evaluation of new sensors – which were also were tested earlier this year on a modified motor at MSFC in Alabama.


In addition to evaluating the performance of the new sensors, the test also monitored an operational pressure transducer recently qualified for flight and flown on STS-114: Space Shuttle Return to Flight launched July 26. These transducers help determine the time of separation of the SRBs (known as SRB Sep) from the External Tank during assent.

MSFC released further information about the testing of the Production Rate Motor – noting the test also will allow NASA and ATK Thiokol engineers to further examine a more environmentally friendly insulation material and to gather information on a pressure-sensitive adhesive that may soon be used on the motor’s joints.

Another objective of the test was to assess the performance of the propellant bore – the hole down the middle – of the rocket motor. When a motor is ignited, a controlled burn begins down its middle, creating the motor’s thrust. The test results will show how motors react during the first few seconds following ignition and provide engineers more information on the firing stability of motors – crucial information for human spaceflight.

Additionally, a powerful X-ray was used during the test to scrutinize how the motor nozzle performs during launch and ascent.

Static firings are part of the ongoing verification of components, materials and manufacturing processes required by the Space Shuttle program.

ATK Thiokol manufactures the Shuttle’s Solid Rocket Motor. The Shuttle’s Reusable Solid Rocket Motor is the largest solid rocket motor ever flown, the only one rated for human flight and the first designed for reuse. Discussions are under way on a potential five segment SRB (currently SRBs are four segments) as part of the SDLV (Shuttle Derived Launch Vehicle) evaluations.


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