According to an ATK statement, the Atlas V rocket used a 10-foot diameter composite heat shield that provides protection for the first stage of the launch vehicle.
(Click Here, to read a story about the X-37B being in-flight for one year.)
The Atlas V rocket carried the X-37B that will support “space experimentation, risk reduction and concept of operations development for a long duration and reusable space vehicle technologies.”
ATK also developed the Atlas V’s Centaur interstage adapter and an 18-foot diameter boat tail connected to the payload fairing.
The parts were made by ATK at its Iuka, Miss., and Clearfield, Utah, facilities.