The Orion contract is a complex project involving Lockheed Martin as the prime contractor and many subcontractors. The contract is structured into three schedules for design, development, testing, production, and operations. Since the initial award, the contract has undergone several changes totaling over $2 billion to realign requirements and accommodate changes to the Constellation program. These changes ensured Orion's design supported its mission of transporting crew to the International Space Station.