WASHINGTON – United Launch Alliance will launch the Air Force’s final Wideband Global Satcom satellite aboard a Delta 4 rocket in 2018, according to a contract modification announced by the Pentagon March 9.

ULA received a $41.8 million contract modification to launch the Boeing-built WGS-10 as part of its $11 billion block buy contract with the Air Force. That deal calls for the production of 36 new Atlas 5 and Delta 4 rocket cores and launch services for vehicles purchased as long ago as 1998.

The modification is part of what the Defense Department described as a mission swap. The Air Force originally included the second GPS 3 satellite in the block buy. But last year the Air Force officials decided to make the launch of that satellite the first competitive Evolved Expendable Launch Vehicle contract in a decade. Air Force officials opted to put the WGS-10 satellite in its place on the manifest.

Now, WGS-10, which will help provide communication for the military anywhere in the world, will launch on a Delta 4 Medium core flanked by four solid-rocket boosters and topped with a 5-meter fairing, the announcement said.

In November, Denver-based ULA said it declined to bid on the 2018 launch of the GPS 3-2 satellite, which will offer improved position, navigation and timing. The move effectively ceded the contract to SpaceX and frustrated lawmakers and Defense Department leaders.

ULA cited several reasons for not bidding, including concerns about its future rights to Russian-built RD-180 rocket engines for national security launches and an inability to certify that funds from other government programs would not contribute to the launch of the Air Force’s second GPS 3 satellite.

Industry officials expect SpaceX will receive a contract award for the launch later this month.