DynaSoar writes "NASA has signed two contracts with US commercial space ventures totaling $3.5 billion for resupply of the International Space Station. SpaceX will receive $1.6 billion for 12 flights of SpaceX's planned Dragon spacecraft and their Falcon 9 boosters. $1.9 billion goes to Orbital for eight flights of its Cygnus spacecraft riding its Taurus 2 boosters. Neither of the specified craft has ever flown. However, the proposed vehicles are under construction and based on proven technology, whereas NASA has often contracted with big aerospace companies for services using vehicles not yet even designed."