Marco Caceres, a space analyst with Teal Group, says the Air Force is most likely interested in having a surveillance platform that can "maneuver in orbit faster" than satellites. Darpa is also working on a new hypersonic "spaceplane" called the XS-1 that could offer quick access to space and launch payloads into orbit for less than $5 million per flight. "Quick, affordable, and routine access to space is increasingly critical for U.S. Defense Department operations," the agency said in its call for proposals for the spacecraft late last year.

"Boeing's cost structure is higher than SpaceX — that's just a fact," said Marco Caceres, senior space analyst at the Teal Group.

Because the aerospace giant has been around longer, it most likely has an older, more experienced workforce with higher wages and labor costs, he added.

But the biggest cost differences likely come from manufacturing processes. Boeing builds its Delta rocket and Atlas V launchers in a vertical position, while SpaceX's Falcon 9 rockets are assembled horizontally, which is easier and saves on time.

Meantime, SpaceX is a vertically integrated company, building all of its parts in-house, with no subcontractors. Boeing employs numerous subcontractors to build components, which adds to costs. "When you become a more established company, you can't be a specialist in everything," Caceres said.

"When it's working it works just fine but, to me, [the May 2014 failure] just sounds like bad workmanship," said Marco Caceres, senior analyst and director of space studies at the Teal Group. "It could be the bolts were poorly manufactured, it might have been corrosion — maybe they didn't screw them on tight enough; who knows?"

Marco Caceres, an analyst with the Virginia-based Teal Group, said the new satellite may be built by France's Thales (TCFP.PA), which has already built several satellites for South Korea. The satellite was likely medium-sized and would cost several hundred million dollars to build, plus another $100 million to launch, he said.

"SpaceX is the new kid on the block, but it's proven its capabilities very quickly," said Marco Caceres, director of space studies with Teal Group, a Fairfax, Virginia-based consultant. "SpaceX would love to be the first commercial company to land its own private astronauts on the moon and eventually go on to Mars."