The last single-stick Delta rocket launched on Thursday, and it was on a show

On Thursday morning, United Launch Alliance 's Delta IV Medium rocket took flight for the final time. Beneath clear blue skies at the Cape Canaveral Air Force Station launch site in Florida, the rocket with the GPS III satellite safely into orbit. This is the second of the Air Force's next-generation global positioning system satellites to reach space.

As usual, the single-core Delta IV rocket performed its job well. Since 2002, this rocket (which can fly with or without small, side-mounted solid rocket boosters) has flown 29 missions. All have been successful.

But the venerable rocket will fly no more. Put simply, in today's marketplace-in which United Launch Alliance must compete with SpaceX for national security launches and with many other providers for commercial missions-the Delta-IV Medium can not compete.

A 2017 report by the US Government Accountability Office put the per-unit cost of a single-core Delta launch at $ 164 million. This is nearly three times the price of SpaceX's Falcon 9 rocket, which can not be compared to comparable or better performance.

To be more effective in this new landscape, United Launch Alliance is phasing out its use of heritage Delta and Atlas rockets in favor of a new Vulcan-Centaur rocket. In dropping the Delta IV Medium, the company is eschewing Aerojet Rocketdyne's costly RS-68A main engine in the less-expensive BE-4 engine under development by the new space company Blue Origin. Similarly, it is seeking to cut costs on Vulcan in other ways, while maintaining its performance.

This is not the last Delta rocket to fly, however. The US Air Force will continue to support the Delta IV Heavy program, which is the second most powerful rocket in existence after the Falcon Heavy-up other heavy-lift emerge alternatives. The final flight is likely to come in 2024, when it lofts a heavy spy satellite for the National Reconnaissance Office.

Listing image by United Launch Alliance