Refurbishment of the Space Shuttle SRMs - the First Reusable Solid Rocket Motors 841530
The solid rocket motors (SRMs) which provide 80 percent of the Space Shuttle's total liftoff thrust are the first and only reusable solid rocket motors ever flown. The expended motors are parachuted back to Earth, retrieved in the Atlantic Ocean approximately 130 miles from the launch site, towed back to Port Canaveral, returned to the Wasatch Division of Morton Thiokol in Utah on railcars, refurbished, reloaded, and returned to the Kennedy Space Center (KSC) for another launch. The steel case components of the SRMs will be used 20 times. The rubber/steel shim flexible bearing in the nozzle, which provides steering capability for the vehicle, will be used for 10 flights before the rubber is removed; new rubber vulcanized to the refurbished metal parts form a new “recycled” flexible bearing which will be good for another 10 flights. The steel and aluminum structures in the nozzle will be used for 20 flights. The safe and arm (S&A) device and the igniter are also refurbished and recycled for a total of 20 flights. Altogether, there are 84 metal parts, two S&As, six operational pressure transducers (OPTs), and over 5,000 pins and bolts that are recovered and reused on every SRM flight set.
Some attrition of hardware has occurred when water impact loads have been more severe than expected. However, 95 percent of the hardware that has been recovered has been acceptable for reuse. Some SRM hardware has already flown five times and nearly all of the hardware from the development and qualification program has also been used in flight motors. This paper will address the refurbishment, acceptance testing, and recycling of the SRM hardware in support of the Space Shuttle program.