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.

"Overall, I would rate it as a success," Marco Caceres, director of space studies with Teal Group, a Fairfax, Virginia-based consulting firm, said in a phone interview.

"It is tricky to hit something that small to begin with, but to hit with the right velocity so that it lands perfectly when the barge is moving in the ocean -- that's a tough challenge," Caceres said. "They're not taking the easy way. That's not the conservative approach."

Marco Caceres, senior analyst at the Teal Group, said the explosion will cause people to question whether NASA should be turning to private companies to launch spacecraft.

"There are people in Congress who say NASA should not be relying on private companies," Caceres said. "Many people will now say, 'We told you so.'"

But there's always a chance of failure with rocket launches, he said, whether it's with a private company or with NASA.

Caceres noted that Orbital has experienced several failures with its Antares and Taurus rocket vehicles. "This is not a good record for Orbital."

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.”

Since 2011, when NASA concluded its final Space Shuttle flight, the US has heavily relied on the rockets as a means of conveyance to the ISS. NASA forks out in the order of $70.7 million to the Russian space agency Rosaviakosmos per seat on a Soyuz capsule. All parties, notes Marco Cáceres of the Teal Group, are happy: Rosaviakosmos gets some cash and NASA gets to have its astronauts on a space station that cost the US tax payer $100 billion.