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ATK chosen to supply Stratolaunch rocket motors

Posted: August 13, 2013

Rocket-builder ATK will design and build first and second stage motors for an air-launched satellite booster under development by Stratolaunch Systems, a start-up launch firm established in 2011 by Microsoft co-founder Paul Allen.

Artist's concept of the Stratolaunch carrier airplane with the Orbital Sciences-provided booster. Credit: Stratolaunch
Stratolaunch is building a contractor team to replace SpaceX, which initially signed on to produce liquid-fueled rockets for the air-launch consortium. But SpaceX dropped out of the Stratolaunch project in 2012, allowing Orbital Sciences Corp. to step in as prime contractor for the company's launch vehicle.

Orbital Sciences operates the air-launched Pegasus rocket, which sends small satellites into orbit from the belly of an L-1011 carrier aircraft.

Stratolaunch aims to scale up the Pegasus concept, claiming the firm's air-launch vehicle, or ALV, can deliver up to 15,000 pounds to low Earth orbit inside a five-meter, or 16.4-foot, diameter payload fairing.

ATK will provide Stratolaunch's first and second stage propulsion. ATK's Utah-based aerospace division also builds rocket motors for the Orbital Sciences Pegasus launcher, but the ALV's motors will be much larger.

"ATK is pleased to receive this award for the development and production of first and second stage propulsion for the Stratolaunch ALV," said Blake Larson, president of ATK's aerospace group. "Our innovative propulsion concept combines both proven and state-of-the-art technologies that will provide a high-performing, cost-effective solution for the ALV."

The contract awarded to ATK by Orbital Sciences covers the design, development and flight hardware for initial Stratolaunch missions, according to an ATK statement.

George Torres, an ATK spokesperson, declined to provide the deal's financial value but said it was a "sizable contract" involving the production of hardware for ground tests and flight articles.

"Our design solution for the ALV will take full advantage of ATK's experience with large diameter solid rocket motors, like those built for the space shuttle and for the Titan 4B launch vehicle," said Scott Lehr, vice president and general manager of ATK's defense and commercial division. "The stages for ALV will also use high-strength, low-weight graphite composite cases, advanced propellants, and heritage materials from ATK's extensive line of commercial solid rocket motors."

Torres said the ATK-supplied motors for Stratolaunch will have larger diameters than the stages used on Orbital's Pegasus rocket, which uses a 50-inch first stage motor. The motors for Stratolaunch will be more similar in diameter to solid rocket boosters produced by ATK for the space shuttle and the U.S. Air Force's Titan 4 rocket, according to Torres.

Stratolaunch's concept of operations includes a custom-built carrier plane with a wingspan of 385 feet. The Stratolaunch mothership, to be designed and manufactured by Scaled Composites in Mojave, Calif., will be powered by six engines cannibalized from Boeing 747 jumbo jets.

Engineers will also harvest the landing gear, hydraulics, avionics and other systems from the 747s.

The 120-foot-long three-stage booster will be dropped from the carrier plane at an altitude of about 30,000 feet. Testing of the mothership should begin in 2016, with the first test launch coming as soon as 2018, according to information on Stratolaunch's website.

Orbital Sciences and Huntsville, Ala.-based Stratolaunch have not announced the selection of a contractor for the air-launch vehicle's liquid-fueled third stage.

Stratolaunch touts its ability to operate the air-launch system from a variety of bases, including Kennedy Space Center, Fla., Wallops Flight Facility, Va., and Vandenberg Air Force Base, Calif.