WASHINGTON — As NASA hashes out an acquisition strategy for building a congressionally mandated heavy-lift launch vehicle that leverages space shuttle and Ares rocket technologies, agency officials are hoping to minimize the potential for a formal protest from industry.

Douglas Cooke, head of NASA’s Exploration Systems Mission Directorate here, said officials are still formulating plans for the Space Launch System that lawmakers directed NASA to start work on this year. In addition to settling on a final design, the agency is sorting through different contracting mechanisms for procuring the heavy-lift vehicle.

Congress expects NASA to make the most of billions of dollars already invested in rocket hardware, including the space shuttle’s RS-25 main engine and solid-rocket boosters, and the J-2X upper-stage engine being developed for the now scuttled Ares 1 crew launch vehicle. Canoga Park, Calif.-based Pratt & Whitney Rocketdyne is prime contractor for the RS-25 and J-2X, while Alliant Techsystems of Minneapolis builds the shuttle’s solid-rocket boosters, which were to be modified for use on the Ares 1.

However, if NASA chooses to leverage this hardware under existing contracts for the heavy-lift rocket, as directed in the NASA Authorization Act of 2010, it could face a challenge from companies that are not currently in the mix. Propulsion provider Aerojet of Sacramento, Calif., for example, has made clear its desire for a competition to build elements of the Space Launch System.

“We need to pick a path where we have mitigated the possibility for a protest to the degree we can,” Cooke said in an April 26 interview. “And no matter what path you take there is always that possibility. You can always get a protest.”

Private companies can challenge a government contract award decision at the U.S. Government Accountability Office (GAO) or the U.S. Court of Federal Claims. Even modifications to existing contracts are fair game when it comes to bid protests, Cooke said, if the changes significantly alter the scope of the work being performed.

NASA has been examining options for the Space Launch System since October, when the 2010 NASA Authorization Act was signed into law by U.S. President Barack Obama. That measure is widely viewed as a compromise between the president’s plan to outsource crew transportation in low Earth orbit while delaying a heavy-lift launcher and Congress’ desire to preserve assets and capabilities associated with the soon-to-be-retired space shuttle. It directs NASA to build a space launch system initially capable of delivering 70 to 100 tons to orbit with an ultimate goal of lofting 130 tons for deep space missions.

In January the agency submitted a preliminary report to Congress detailing a reference vehicle design based on shuttle and Ares technologies, though it said more time was needed to determine the most cost-effective and sustainable design for the new rocket. NASA is currently studying options in addition to the shuttle- and Ares-derived system but also vehicles that would rely on kerosene-fueled main engines — the RS-25 is liquid-hydrogen fueled — as well as designs based on the existing Atlas 5 and Delta 4 rockets.

Shortly before the report was delivered to lawmakers in January, Aerojet urged NASA to hold a competition to build the new heavy-lift vehicle. Aerojet, which builds both liquid- and solid-fueled rocket motors, could be left without a significant role in the Space Launch System should NASA pursue a vehicle based on existing propulsion systems.

“With propulsion constituting a significant portion of the [heavy-lift vehicle’s] cost, Aerojet believes that a key tenet to developing an affordable solution for the NASA Heavy Lift Vehicle is to incorporate competitive procurements for propulsion — both solid rocket motors and liquid rocket engines — that is used to power the [heavy-lift vehicle],” Aerojet Vice President Julie Van Kleeck said in a Dec. 1 letter to senior NASA officials including Cooke and Michael Wholley, the agency’s general counsel.

“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,” Van Kleeck wrote, noting that Aerojet won NASA’s last full and open competition for a large solid rocket, the Advanced Solid Rocket Motor, which was canceled in the 1990s due to funding woes. “We are requesting information on government-owned assets, tools, designs, and equipment to support a competitive bid should this be the direction selected,” she wrote.

Cooke said NASA is still determining how much overlap exists between Congress’ Space Launch System performance specifications and the work carried out to date on Ares 1, which was designed to deliver astronaut crews to low Earth orbit in its early missions.

“The configurations [of the heavy-lift launch vehicle] are going to be more capable than what Ares 1 could do, so then we have to understand how the current contracts apply or don’t, or what exactly that path should be,” he said.

If NASA opts to pursue the heavy-lift launcher by modifying existing space shuttle and Ares contracts, and a bid protest is filed with GAO, Cooke said work on those contracts would cease until the protest is resolved.

“It would be very tough to work through,” he said.