Delta 4 prepared to launch NROL-25 mission from Vandenberg Air Force Base, California. Credit: ULA

WASHINGTON — The U.S. Air Force plans to award United Launch Alliance a contract to build a Delta 4 rocket for launch in October 2017 as part of the service’s 2013 block buy contract with the company.

The $11 billion block buy contract includes production of 36 new Atlas 5 and Delta 4 rocket cores and launch services for vehicles purchased as long ago as 1998.

According to a special notice posted to the Federal Business Opportunities website Sept. 8, the rocket would feature a 5-meter fairing and two sold-fueled strap-on boosters and launch from Vandenberg Air Force Base, California, in October 2017.

The announcement did not identify the payload or government customer for the launch. The Air Force expects to award the sole source contract Sept. 30, the notice said.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.