Purchasing core elements used to launch 28 rockets into space for National Security Space missions is the focus of negotiations between the Air Force and United Launch Alliance to establish a requirements contract, according to Defense Under Secretary Frank Kendall.

The plan is to procure 36 Evolved Expendable Launch Vehicle cores over a five-year period, beginning in Fiscal Year 2013, according to a memo from Kendall to Secretary of the Air Force Michael B. Donley. Kendall is the under secretary for acquisition, technology and logistics.

According to Donley, the purpose of the space launch acquisition is to balance operational needs with lowering launch costs and foster competition.

"Our fundamental priorities are to be good stewards of the American taxpayer and control cost growth through further competition," said Donley.

"We will continue to work with potential new entrants as they progress toward certification, all the while maintaining mission assurance." Donley added that the Air Force will achieve these goals through launching national security satellites like GPS and other critical military missions.

A core is defined as the basic cylindrical unit of the rocket used to launch a payload into space.

Some payloads require three cores combined together in a "heavy lift" configuration to reach the prescribed orbit. The 36 launch vehicle cores represent a total of 28 launches, including 24 single core launches and four requiring the "heavy lift" configuration.

This space launch acquisition approach is based on the United Launch Alliance response to the Air Force's March 2012 request for proposal, a new entrant independent assessment, and an assessment of space vehicle deliveries.

"We made an informed decision based on criteria to the Congress about a year ago," said Scott Correll, Air Force Program Executive for Space Launch.

"This acquisition decision provides the best balance between operational requirements, budget and enabling a competitive environment. It also allows us to reduce costs while maintaining our focus on the warfighter and delivering 100 percent mission success.