According to reports, a United Launch Alliance Delta 4-Medium+ vehicle will be launched on Wednesday night with help of an advanced main engine on a similar rocket. It will carry a $566 million Air Force communications satellite.

As per reports, the improved RS-68A main engine will support the medium-lift rocket at Cape Canaveral's Complex 37 with the Wideband Global SATCOM satellite No. 7, which is for a super-synchronous transfer orbit.

And the launch opportunity is from 8:07 to 8:46 pm EDT. A 60% chance of favorable conditions has been predicted for launch, and clouds and lightning could become concerns.

ULA and propulsion-provider AerojetRocketdyne have gradually stopped using the original RS-68 engines supporting flying A-models of the powerplant on all future vehicles of Delta 4, regardless of configuration of the rocket.

In June 2012, the RS-68A program launched three engines aboard a Delta 4-Heavy rocket that was carrying a huge National Reconnaissance Office satellite into geosynchronous orbit. These launches were related to Delta 4- Heavy Upgrade initiative.

According to Ron Fortson, ULA director of mission management, "We've used RS-68A to standardize our Common Booster Core that can support any of our Medium configurations - the 4,2, the 5,2 and the 5,4, while still giving us that lift capability of each of those configurations".

Fortson added it was aimed at increasing performance in addition to making the booster common for improved manifest flexibility. He also said that commonality also cut a lot of their costs related to production engineering.