Motors Redesigned Following Challenger Disaster

Alliant Techsystems' Reusable Solid Rocket Motors (RSRM) passed a major milestone this weekend, as they successfully powered NASA's space shuttle Discovery and its crew during Sunday's launch. The motors launched were the 100th flight set since the redesigned RSRMs were first flown more than 20 years ago.

"The launch of the 100th flight set of NASA's twin boosters for the Shuttle is another demonstration of ATK's commitment to safety and mission success," said Mike Kahn, ATK Launch Systems Executive Vice President and General Manager.

During Sunday's flight the boosters provided the main thrust at liftoff, generating an equivalent of 15 million horsepower each and launching the shuttle to an altitude of approximately 28 miles. After two minutes of flight, ATK's 16 Booster Separation Motors (BSMs) performed flawlessly. Four BSMs on the forward skirt and four on the aft skirt of each booster fired to jettison the boosters safely away from the shuttle orbiter and external tank, enabling the rocket motors to parachute back down through the Earth's atmosphere to be recovered and reused.

Over the past 20 years, ATK says both it and NASA have made substantial investments in process automation, engineering modeling, and inspection techniques that have enabled significant improvements to flight safety margins, increased mission reliability, and extended service life and reusability.

Current motors have had the benefit of 27 full scale ground tests, including a successful five-segment margin test performed in 2003, and numerous subscale and material characterization tests that anchor complex analyses with hard data.

"Transitioning the boosters and related critical skills to Ares I will provide substantial benefit from all the experience and progress gained over the years and enable significant risk reduction to the program," said Kahn. "Our task is now to continue our commitment to quality and success as we support the remaining shuttle flights and prepare to launch Ares I-X and Ares I."

The RSRMs and BSMs will be used for the remainder of the Space Shuttle Program with similar versions being used on NASA's Ares I, the launch vehicle that will replace shuttle missions to the ISS as well as conduct future lunar missions. ATK is the prime contractor for the Ares I five-segment first stage.

FMI: www.atk.com, www.nasa.gov/shuttle