The U.S. Air Force has kept an unmanned space shuttle in orbit for the past two years, and it seems no one without security clearance knows what it’s been doing up there.
The X-37B Orbital Test Vehicle, which can enter orbit and land without human intervention, is scheduled to touch down this week—the best guess is sometime on Tuesday—at Vandenberg Air Force Base, northwest of Santa Barbara, Calif. The landing will mark completion of the program’s third and longest mission, which was launched on Dec. 11, 2012. The Air Force has two such spacecraft for these low-earth orbit missions, all of which are classified, as are the precise launch and landing times.
“The mission is basically top secret,” says Captain Chris Hoyler, an Air Force spokesman. The X-37B program came from technologies developed by Boeing (BA), NASA, the Air Force, and the Defense Advanced Research Projects Agency (Darpa).
Boeing’s description of the craft says the Air Force uses it to “explore reusable space vehicle technologies in support of long-term space objectives.” Hoyler described the X-37B as a test platform “to advance the state of the art” in areas such as “thermal protection systems, solar power systems, thermal control, environmental modeling, autonomous control and landing, and control algorithms.”
The one definitive thing the Air Force will say about the X-37B is that it has no plans to develop a manned version. The spacecraft measures 29 feet long and 9.5 feet high, about one-fifth the size of the retired NASA space shuttles that seem to have inspired its appearance. It has a payload bay that opens in space, just like the larger space shuttles. The first X-37 mission ended in December 2010 after almost eight months in orbit.
The X-37B “is clearly a military program that no one has necessarily felt the need to justify politically,” says Laura Grego, a senior scientist in the global security program at the Union of Concerned Scientists. She says the spacecraft’s likely missions could probably be handled by satellites and other platforms at lower cost to taxpayers.
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-1that 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.
Regardless of what the X-37B does in space, the Air Force appears to be planning a future for the program. Earlier this month, NASA said it had agreed to let the Air Force use two former space shuttle hangars at Kennedy Space Center in Florida to prepare the X-37B for launches. The craft is sent into orbit atop the Atlas V rocket, designed and built by the United Launch Alliance, a Boeing-Lockheed Martin(LMT) joint venture. The Air Force also wants to be able to land the craft in Florida, which, as with the space shuttle program, saves a cross-country return trip and makes it easier to prepare for the next flight.
As with many top-secret Pentagon programs, speculation has flourished online about what the government is doing with the spacecraft. Theories range from surveillance to, well, more surveillance involving satellites that are so secretive they can only be released in space. Others have suggested the craft is the platform for a new generation of kinetic weapons that can be used from space. (Here’s a look at one theoretical space weapon at the center of speculation by defense and tech nerds for more than a decade.)
Lest one scoff at the notion, the U.S. military has been testing such hypersonic weapons for several years from earth-based launch systems. Moving one into space may pose additional technical and financial challenges, but it’s hardly impossible. “The basic problem with these ‘orbital bomber’ and Starship Trooper ideas is that they would cost trillions of dollars—all to deliver a thimbleful of force,” former RAND Corp. analyst John Arquilla wrote.
One even farther-fetched theory? The Air Force is testing the craft so it can eventually drop special-forces soldiers from space to anywhere on the planet, within minutes.