WASHINGTON — As NASA settled last year on a congressionally mandated heavy-lift launch vehicle design based on propulsion technologies already in development, rocket-engine manufacturer Aerojet was making a case for opening up key elements of the launcher to competition.

The proposed vehicle design — detailed in a Jan. 10 preliminary report to Congress called for in the NASA Authorization Act of 2010 — would incorporate a liquid hydrogen-fueled core stage based on the existing space shuttle RS-25 main engines and external tank, plus two five-segment solid-rocket boosters and an upper stage powered by a J-2X engine.

Both the five-segment boosters and the J-2X engine are already under contract — to Minneapolis-based Alliant Techsystems (ATK) and Canoga Park, Calif.-based Pratt & Whitney Rocketdyne, respectively — as part of the Ares rocket program U.S. President Barack Obama has proposed canceling. Pratt & Whitney Rocketdyne also built and now maintains the shuttle’s reusable RS-25 main engines. Sacramento, Calif.-based Aerojet — the smallest of the three main U.S. propulsion firms — told NASA last month that it wants a shot at unseating ATK and Pratt & Whitney Rocketdyne if the agency moves forward with a heavy-lift rocket that incorporates the five-segment boosters and J-2X engine.

“Although we believe an affordable and sustainable NASA [heavy-lift vehicle] must include alternatives to the existing propulsion solutions or new propulsion development, we do intend to compete for the 5-segment solid, the J2X/, and/or expendable RS-25 propulsion solutions if they are selected,” Aerojet’s vice president of space and launch systems, Julie Van Kleeck, wrote in a Dec. 1 letter to NASA’s associate administrator for exploration systems, Doug Cooke.

She said Aerojet has requested information regarding government-owned assets, tools, designs and equipment available to support a competitive bid.

“If this approach is selected, Aerojet will compete for the RS-25 integration support of the existing engines as well as the development/qualification for the expendable variant,” Van Kleeck wrote in the letter.

The letter, a copy of which was obtained by Space News, also was sent to Bill Gerstenmaier, NASA’s associate administrator for space operations; Woodrow Whitlow, associate administrator for mission support; and NASA General Counsel Michael Wholley.

Van Kleeck said the company also is positioned to compete in the liquid-propulsion arena, should NASA ultimately choose an all-liquid fueled rocket design for its next-generation heavy-lift rocket.

“Aerojet has the core competency to develop and produce large liquid engines regardless of propellant or cycle,” she wrote, adding that the company had presented several heavy-lift strategies to an internal NASA study team evaluating architecture options for future manned exploration missions.

Although NASA has yet to deliver a formal response to Aerojet, Cooke said NASA continues to evaluate alternatives to the space shuttle-derived heavy-lift launch vehicle, as well as acquisition strategies for its development.

“We have to go through the discussion on procurement laws and that sort of thing and understand how requirements map between what we’re doing now and what the heavy lift would need,” he told Space News in remarks following a Jan. 11 presentation of the agency’s baseline heavy lift design to the NASA Advisory Council’s exploration subcommittee.