Air Force's mystery space plane again heading into space

Intrigue continues to shroud a small prototype unmanned space plane that the U.S. Air Force hopes to launch on Friday from Cape Canaveral in Florida.

The first X-37B returned to Earth in December after finishing its 225-day journey. That mission, too, was classified and the military said little other than that it was pleased as punch with the results.

So what's the project all about? The sometimes fevered speculation that's accompanied the project from the start has been annotated by the usual questions: Will the X-37 serve as the prototype for a new kind of James Bond-like spy ship? Could it sneak up on rival countries' satellites and zap them with a laser?

On Wednesday, the Union of Concerned Scientists, which has been critical of the program, added its voice to the debate, registering a public complaint about the vehicle's practical use. "Because of its weight and relative lack of maneuverability, the space plane is not well-suited for a number of missions," wrote Laura Grego, a scientist with the group's Global Security Program "For example, it would have a harder time carrying payloads into orbit, maneuvering in space, rendezvousing with satellites, and releasing multiple payloads. Yes, the space plane may offer more flexibility and is potentially reusable, but that comes at a very high price compared with the alternatives. We have not seen an analysis that shows why it is worth that high price."

In the past, Air Force officials have rejected suggestions that the X-37 project was designed with the intention of "weaponizing" space. And they're still on message. In its most recent statement, the Air Force said that the program was designed to test reusable technologies for future American space exploration as well as for "operating experiments" which researchers can later examine back on Earth.

That and 25 cents won't be enough to get you on the subway. So it's still watch and wait.