Aerojet Rocketdyne’s merger leaves the company with two entries in the NASA competition for a propulsion system to power advanced strap-on boosters for the heavy-lift Space Launch System (SLS) in development, and the company apparently will keep both in play until the market makes a choice.

Aerojet has been building on work with the U.S. Air Force to propose a 1-million-lb.-thrust, hydrocarbon-fuel engine designated the AJ-1E6 for the NASA application, which would use four of the staged ox-rich combustion cycle rocket engines to power each of the twin strap-on boosters needed to get the SLS to the 130-metric-ton capability mandated by Congress.

Meanwhile, Rocketdyne is teamed with Dynetics Inc. of Huntsville, Ala., on a $73.3 million study contract to demonstrate components of an Apollo-era F-1 kerosene main engine, updated with modern manufacturing techniques, to power the advanced boosters. At 1.8 million lb. of thrust, only two of the big old engines would be needed for each booster.

“We’ll stay focused on what customers want,” Warren Boley, Jr., president and CEO of the merged companies and former president of Aerojet, told reporters in a telephone press conference June 18.

The F-1 uses the gas-generator cycle, which burns some fuel to spin the turbomachinery and then vents it off the vehicle in what is also called an open cycle. Modern Russian engines use the staged combustion cycle, which burns some of the fuel in a preburner to turn the turbomachinery, and then injects the plume back into the combustion chamber to retain its energy as the rocket fires.

“In the launch business, the new American engine, what happens with staged, ox-rich combustion is a focus for both companies,” Boley said. “The debate between gas generator cycle and staged ox-rich will get resolved.”

Long-term, Boley said, he wants the new company to develop “a complete technology suite that satisfies all customers, affordably.” Also in the works for the combined companies are a throttleable, restartable solid-fuel motor that will “look like a liquid” fuel engine, he said, and a Mach 4 test of its air-breathing hypersonic propulsion technology “this year.”

The company is also interested in using its advanced solar-electric propulsion technology in NASA’s planned effort to capture a small asteroid and nudge it into a high lunar orbit.

“We’re excited about using solar electric propulsion to go get that asteroid,” Boley said.