STAR 48GXV Motor with Composite Case Successfully Tested for Solar Probe Plus Mission

ATK and NASA successfully tested a proof-of-concept STARTM 48GXV motor for the Solar Probe Plus mission, which will enter the sun's atmosphere to study the streams of charged particles the sun hurls into space.

The STAR 48GXV solid-fuel third stage will provide the boost needed to assist the Solar Probe Plus spacecraft in escaping Earth's orbit to begin its approach of the sun.

Solar Probe Plus is scheduled to launch in 2018 on an Atlas V rocket. ATK's STAR 48GXV motor is based on the venerable STAR 48BV rocket, with roots dating back to the late 1970s and hundreds of successful Delta II-class missions. The new STAR 48GXV motor incorporates many new technologies, including lightweight composite case and exit cone materials, and advanced thrust vector controls.

"This test highlights ATK's ability to design, develop and manufacture highly engineered products to support a wide range of customer needs," said Cary Ralston, vice president and general manager, Missile Products division. "The STAR 48GXV ushers in a new performance standard for solid-propellant upper stage motors."

With its high-strength graphite composite case, the STAR 48GXV motor can operate at approximately three times the chamber pressure of its predecessor. The filament-wound case significantly reduces the cost and lead time associated with thin-walled titanium cases. The ignition train incorporates a consumable Vespel® igniter initiated by a high voltage initiator. The exit cone, manufactured at ATK's facility in Promontory, Utah, is a lightweight carbon-carbon structure that eliminates the need for support structures. ATK's thrust vector electronic control system (TVECSTM), which includes electro mechanical actuators and a digital controller, is used to command the vectorable nozzle to achieve the desired thrust vector.

The STAR 48GXV motor test, conducted at ATK's facility in Elkton, Md., provided key subsystem performance data for the final design, development and qualification effort to support the Solar Probe Plus mission. The Solar Probe Plus spacecraft, which will fly through the sun's outer atmosphere (called the corona) several times to gather data on the processes that heat the corona and accelerate the solar wind, is being developed at the Johns Hopkins Applied Physics Laboratory in Laurel, Md. Solar Probe Plus is part of NASA's Living with a Star program, managed by NASA's Goddard Space Flight Center in Greenbelt, Md., for the Science Mission Directorate at NASA Headquarters, Washington.