A heavy-lift version of the company's Delta IV rocket is fully assembled for a planned June 4 blastoff from Launch Complex 37 with a classified intelligence mission.
The National Reconnaissance Office payload last Friday was attached to the rocket featuring three core boosters that will generate about 2.1 million pounds of thrust at liftoff.
The launch — the seventh by a Delta IV Heavy — is scheduled between 1:30 p.m. and 6:35 p.m. A more precise window will be released closer to the launch date.
The big rocket was last seen in late 2014 launching NASA’s prototype Orion crew exploration capsule on a first, unmanned test flight.
ULA also has confirmed a June 24 date for the next launch of its Atlas V rocket, which will fly from Launch Complex 41 in its most powerful configuration.
Five solid rocket boosters will combine with the rocket's Russian RD-180 main engine to produce about 2.5 million pounds of thrust, lifting a heavy Navy communications satellite on its way to an orbit more 22,300 miles over the equator.
Liftoff is scheduled for 10:30 a.m., at the opening of a 44-minute window.
Once planned for early May, ULA has delayed the mission about seven weeks due to an early engine shutdown during the most recent Atlas V flight on March 22.
The RD-180 shut down six seconds too soon during that launch of International Space Station supplies, but the upper-stage engine burned for an extra minute to successfully complete the mission.
ULA engineers concluded a faulty valve prevented the main engine from burning enough kerosene fuel, and planned to inspect their entire engine inventory for any similar flaws.
Amid that work, the rocket now targeting a June 24 launch has been stacked in its processing tower and awaits delivery of the Navy's fifth Mobile User Objective System satellite.
After the delay, ULA is sorting out the timing of as many as nine more missions it could launch this year from Cape Canaveral and California.
