ATK’s [ATK] Reusable Solid Rocket Motors (RSRMs) supported the final flight of Space Shuttle Endeavour yesterday as they ignited at 8:56 a.m. EDT sending the crew on their 11-day mission to the International Space Station (ISS).
The recovery and reuse of boosters after each flight enables NASA and ATK to collect vital post-flight information and performance data, confirming a safe and robust design. If the cases pass inspection they can be used up to 20 times; the ones used in yesterday’s launch have collectively flown on 59 previous shuttle missions and been used in 11 ground tests.
“The post-flight data we’ve gained from recovering the boosters over the past three decades has provided the knowledge to truly understand the motors’ performance and make improvements throughout the program, leading to the most understood and most reliable human-rated solid propulsion system in existence,” said Blake Larson, ATK Aerospace Systems Group president. “As we develop America’s Space Launch System it is vital we leverage this expertise.”
Since the inaugural flight of the space shuttle, 268 space shuttle solid rocket motors have been launched and 53 full-scale ground tests performed, enabling ATK and NASA to constantly improve safety, techniques and processes.
The 149-foot-tall solid rocket boosters each produced more than 15 million horsepower, safely launching the shuttle to approximately 28 miles in altitude in just over two minutes. After the flight, the RSRMs were jettisoned from the orbiter and external tank by ATK’s 16 Booster Separation Motors (BSMs). Each booster has eight BSMs: four on the forward skirt and four on the aft skirt. The separation motors propelled the RSRMs to a safe distance from the shuttle orbiter, enabling the spent boosters to parachute down through the Earth’s atmosphere where they splashed down into the ocean for recovery.
In addition, ATK supplied the titanium hydrazine propellant tanks for the space shuttle Auxiliary Power Unit (APU). Three APU tanks house the hydrazine fuel that generates power for the shuttle’s hydraulic system. These tanks have performed perfectly for each of the shuttle’s three decades of operations.
While continuing to safely fly the space shuttle, ATK is furthering the development of its upgraded five-segment solid rocket motor. Currently ATK is preparing to ground test the third full-scale Development Motor (DM-3) and to complete a 90 percent Design Review, both this year.
“We are extremely encouraged by the data we have collected from the first two ground tests of the five-segment motor,” said Charlie Precourt, ATK’s vice president and general manager, Space Launch Systems. “With this new motor we have been able to leverage the knowledge and hardware from the heritage shuttle program and upgrade to better materials to build a higher performing, more reliable solid rocket booster that can support NASA’s heavy lift vehicle.”
Modifications to the motor include an added fifth segment, changes to the propellant grain, a larger nozzle opening, and an upgraded liner and insulation material–all designed to meet performance requirements and increase reliability while lowering manufacturing costs.
“We were able to incorporate many design changes during the development of the five-segment motor that we identified during the shuttle program but were not able to make given the shuttle vehicle’s operations tempo,” said Precourt. “We also incorporated materials and streamlined processes that have been flight-proven in our commercial programs.”