Spaceflight Now is reporting that the US Air Force has agreed to purchase 36 booster cores as part of a deal with United Launch Alliance:
A blockbuster rocket-buying agreement has been signed between the Air Force and United Launch Alliance, the supplier of boosters for national security spaceflight.
The deal aims to produce 36 booster cores for the Pentagon’s use over the next few years of Atlas 5 and Delta 4 Evolved Expendable Launch Vehicles. Delivery of the rockets through 2017 comes at a savings of $4.4 billion over previous estimates in President Obama’s FY 2012 budget….
The first batch of 7 cores under the three dozen Block Buy are four Air Force missions — Atlas 5-501, Atlas 5-511, Delta 4 Medium+ 4,2 and 5,4 rockets — and one Delta 4-Heavy for the National Reconnaissance Office.
The goal strives to stabilize the rocket production business while giving the government the advantage of buying in bulk to drive down the costs of putting satellites into space.
The Delta IV uses three cores while the Atlas V uses a single one.