Marco Caceres, an analyst with the Teal Group, says there is a strong business case for ULA to retire the Delta IV, as the cost for keeping two redundant lines is significant. But he also acknowledged that there is a smart political angle at work. "If they were to cancel the Delta IV medium and all they have is the Atlas V, then there is a better argument to be made for preserving the RD-180 shipments," Caceres said. "No question about that. Have they thought about it? I'm sure people at ULA have considered it as a good strategic move."

But, Caceres said, there are many practical reasons for ULA to move away from the Delta IV, a largely redundant and expensive capacity. He notes that part of the reason Bruno was brought in to lead ULA last summer was to streamline the company in the face of SpaceX's competition. "If the Air Force wants ULA to be more competitive on price, it has to become leaner, and it can't do that with two redundant systems," Caceres said.

Marco Caceres, senior space analyst for the Fairfax, Virginia-based Teal Group, said there have been no public disclosures of any anomalies in the April 18 mission. Caceres, who follows the launch industry, said that even if there was a glitch with the mission, such as falling short of the intended orbit, it was a success because the SpaceX vehicle was able to dock with the space station. “Rockets don’t usually fall short in delivering their payloads to the intended orbit, but it happens on occasion,” he said. “It’s certainly legitimate for Rogers to ask.”