The craft, currently in orbit, has simultaneously been the Air Force's best- and worst-kept secret. Knowledge of the X-37 is widespread. Knowledge about the X-37 is scarce.
It's hard to hide a launch into space, so experts knew the unmanned X-37 Orbital Test Vehicle's fourth mission began on May 20 aboard an Atlas V rocket. And it was reported that amateur space enthusiasts have even been able to spot the craft in orbit with their telescopes.
But Hyten, head of Air Force Space Command, and other officials have remained tight-lipped about the vehicles' payload or ultimate purpose.
The secrecy around the program has faced some criticism that it could lead to a space arms race, with nations looking to counter each other's space-based capabilities.
China's official state-run news agency remarked in May – shortly after the spacecraft's most recent launch – that "the exact purpose of the X-37B was never revealed and the secrecy surrounding the project has led to speculation that the solar-powered X-37B can be used as a spy satellite or to deliver weapons from space."
Asked about the topic Sept. 15 at the annual Air Force Association Air and Space Conference near Washington, D.C., Hyten said he was satisfied with the X-37 and the public perception of the craft.
"I like the way the X-37 works. I like what it does, and I like the message that it sends to the world," he told reporters. "I like the fact that the X-37 is up there operating. I like the fact that we get to use its capabilities. And the broader message of how that goes to the world – that's just fine with me. I have no problem with that."
Air Force Times reporters who inquired about the plane were given statements that are publicly available on the Air Force's website.
"The primary objectives of the X-37B are twofold: reusable spacecraft technologies for America's future in space and operating experiments which can be returned to, and examined, on Earth," the statement reads.
"Technologies being tested in the program include advanced guidance, navigation and control, thermal protection systems, avionics, high temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, advanced propulsion systems, and autonomous orbital flight, reentry, and landing," it says.
An August "Air Force Tech Report" video from the service – normally used to inform the public about the planes and equipment used by the Air Force – instead simply summarized the questions surrounding the craft.
"So what was it doing up there for 224 days?" the video asks, referencing the length of the X-37's first mission in 2010.
"It was, " the video begins. Then a censoring beep is heard and the words "Top Secret" appear on the screen.
"Okay, I can't tell you," the narrator says. "But what do you think? Was it conducting reconnaissance missions? Tampering with enemy satellites? Is it a space bomber? Or all of the above? We don't know exactly what it does, but it's safe to surmise that the X-37B will have a vital role in the future of Air Force warfare."
As of September, it appeared that the video had been taken down from both the Air Force website and YouTube channel, and was only available via the website Space.com.