Tweaked ATK Star 48 Motor Debuted in TacSat-4 Launch

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The Sept. 27 launch of an experimental U.S. military communications satellite marked the debut of a new variant of ATK’s Star 48 line of upper stage motors that the company says offers greater flight precision and flexibility.

The Star 48BV motor served as the fourth stage on a Minotaur 4-plus rocket that launched the Navy’s TacSat-4 communications satellite to low Earth orbit from Kodiak Island, Alaska. The motor features a flexible nozzle and thrust vector electronic control system (TVECS) that provides better maneuverability and control, the company said in a Nov. 28 press release.

Earlier versions of the Star 48 motor have used a fixed, nonmoveable nozzle.

While a similar version of the Star 48BV was developed in the early 1990s for NASA’s Commercial Experiment Transporter program, the controller used older technology and never had the opportunity to function. The first stage of the Conestoga 1620 rocket launch carried the Star 48 but was destructed because of a first-stage malfunction and the Conestoga did not fly again, ATK spokesman Rod Gibbons said in an emailed response to questions.

“The TVECS system is the latest innovation in controls technology,” Gary Flinchbaugh, vice president and general manager of ATK Propulsion and Controls, said in a statement. “We’ve designed TVECS to be adaptable for a variety of missions and payloads requiring more precise control of thrust from solid propulsion and attitude control systems.”

Between the new nozzle and electronic control system, the rocket is kept stable and flies on its intended path. The new version of the Star 48 has a control system that keeps the rocket from spinning, which is helpful for spacecraft that may have fuel, structure or sensors that can’t tolerate excessive force from spinning at a higher speed, said Mike Lara, vice president of strategy and business development for ATK Propulsion and Controls in Elkton, Md. The control system replaces the need for spinning a payload, he said.

According to the press release, the newly developed thrust vector control hardware and software can be used for missiles, satellites and other space vehicles.

In an interview, Lara declined to disclose the cost or source of funding for the motor upgrade.

Variants of the Star 48 motor have flown more than 100 missions dating back to the 1970s, Lara said.

The next flight of the Star 48BV is scheduled for May 2, 2013, with the launch of NASA’s Lunar Atmosphere and Dust Environment Explorer aboard a Minotaur 5 rocket, ATK said. Minotaur rockets, built by Orbital Sciences Corp. of Dulles, Va., utilize excess ICBM stages.