WASHINGTON – As the United Launch Alliance prepares for the final launch of its Delta 4 Medium rocket on Thursday, the company is also downing the last five missions with the Delta 4 Heavy.
Gary Wentz, ULA vice president for government and commercial programs, said Delta 4's final major mission is currently scheduled for the second half of 2023 next year, "Wentz said during a conference call on August 20 Launch of GPS-3 on Thursday. "Then we have two in the last part of  22 and the final is scheduled for 2023."
A ULA spokesman said that all future Delta 4 Heavy missions should support "our US Air Force / National customers of the reconnaissance bureau."
The two Delta 4 Heavy launches scheduled for 2020 are, according to Spaceflightnow, the NROL 44 Mission of the National Reconnaissance Office at Cape Canaveral, Florida; and NROL-82 at Vandenberg Air Force Base, California.
ULA also builds Delta 4 Heavy hardware for three NGO missions as part of a contract for launch vehicle production for 201
Additional contract awards are expected in in the coming months for the actual launches of NROL-70 and NROL-91 in 2022 and NROL-68 in 2023.
ULA introduces the Delta 4 Heavy in favor of Vulcan, its next generation rocket I Wentz said he would fly for the first time in April 2021. The Delta 4 Heavy is an expensive missile that costs more than $ 350 million to launch and is limited to government customers. While the ULA Delta 4 Heavy price reportedly dropped below $ 300 million, it is still considered too expensive to be commercially viable.
For certain government payloads, such as large-map spy satellites, Delta 4 Heavy remains an attractive proposition.
"We continue to fly the Delta 4 Heavy through the later part of 2023 for certain payloads that require this capability and the mission capture safeguards we provide," he said. "We will continue to fly this as long as the customer deems it necessary, and we have planned a ramp for Vulcan Centaur to provide some overlap for this capability and provide additional redundancy to our customers."
Delta 4 Heavy uses three rocket propulsion loaders in its first stage to transport 14,200 kilograms into the geostationary transfer orbit. The launch capacity of the rocket was unprecedented in the US until the launch of the Falcon Heavy by SpaceX last year, with 26,700 kilograms thrown into orbit.
Delta 4 Heavy has been launched eleven times since 2004. Apart from the unexpectedly low performance on its first mission, the heavy-duty missile – like the rest of the current ULA fleet – has not suffered any failure.
ULA's Delta 4 medium, which uses a first stage of liquid fuel and smaller solid fuel boosters, has been launched 28 times. Its 29th and final mission will transport the Luftwaffe's second GPS-3 satellite on August 22.