ULA's Delta 4 Heavy until its last five missions

WASHINGTON – As United Launch Alliance prepares for the latest launch of its Delta 4 Medium rocket on Thursday, the company is also counting down its last five missions with the Delta 4 Heavy.

Gary Wentz, vice president of government and business programs at ULA, said the latest heavy Delta 4 mission is currently scheduled for the second half of 2023.

"We have two planes scheduled for the months of June and September of next year," Wentz said at a teleconference on Aug. 20 on the scheduled launch of Thursday's GPS-3. "Then we have two programmed in the last part of [20]22 and the final is a launch in 2023. "

A spokesman for ULA said all future Delta 4 Heavy missions should "support our US National Air Force / National Reconnaissance Office client."

The two Delta 4 Heavy launches planned for 2020 are the NROL-44 mission of the National Reconnaissance Office in Cape Canaveral, Florida, and the NROL-82 at Vandenberg Air Force Base in California, according to Spaceflightnow.com.

ULA also builds Delta 4 Heavy equipment for three NRO missions under a 2018 launch vehicle production service contract worth $ 467.5 million following a $ 149 million change USD in May and 156.7 million USD earlier this month.

Additional contracts are expected in the coming months to cover the actual launches of NROL-70 and NROL-91 in 2022 and NROL-68 in 2023.

ULA is phasing out the Delta 4 Heavy in favor of Vulcan, its next-generation rocket, scheduled for launch by Wentz in April 2021. The Delta 4 Heavy is an expensive rocket that costs $ 350 million in launch, limiting its use to customers government. . Although the ULA Delta 4 Heavy price has fallen below $ 300 million, it is still considered too expensive to be commercially viable.

For some government payloads, such as expensive spy satellites, Delta 4 Heavy remains an attractive attraction.

"We continue to fly the Delta 4 Heavy until the end of the year 2023 for specific payloads that require this capability and assurance of mission success we deliver," he said. "We will continue to use them as long as the customer knows the need, and we have planned an access ramp for Vulcan Centaur to allow us to overlap this capability, which will provide additional redundancy to our customers." "

In the first stage, Delta 4 Heavy uses three liquid rocket propellant propellants to propel 14,200 kg into a geostationary transfer orbit. The rocket's lift capacity was unparalleled in the United States until SpaceX introduced Falcon Heavy last year, able to propel 26,700 kilograms into this orbit, also using three liquid rocket cores.

Delta 4 Heavy has been launched 11 times since its launch in 2004. Aside from underperforming performance on its first mission, the high-load rocket – like the rest of the current ULA fleet – has not known failure.

ULA's Delta 4 Medium, which uses a liquid propellant first stage supplemented by smaller solid fuel boosters, was launched 28 times. Its 29th and final mission will carry the second GPS-3 satellite of the Air Force on 22 August.