Behind the Air Force's Secret Robotic Space Plane

Move over NASA. The U.S. Air Force has spent decades on the concept: an unmanned space plane that can be used to spy, reposition satellites, possibly even bomb targets, then return to base. A successful launch next week could turn that vision into a reality.

 

When the engines of a 19-story Atlas V ignite in April at Cape Canaveral Air Force Station in Florida, the liftoff will look like any other for the workhorse launch vehicle. After about 4 minutes, the engines will cut off and the rocket's first stage will fall away, freeing the second stage to boost the upper section of the rocket into low Earth orbit.

Away from prying eyes, the mission will cease to be ordinary. A few seconds after the second stage fires, the fairing, a protective shroud that surrounds the cargo at the rocket's tip, will split in half, revealing the classified payload: a 29-foot-long delta-wing spacecraft called the X-37B Orbital Test Vehicle. It might look like a miniature version of the space shuttle, but this spacecraft is unmanned, and instead of NASA, the U.S. Air Force is operating it. The moment the X-37B emerges from the shroud will mark the fulfillment of a dream the Department of Defense has been pursuing for nearly 50 years: the orbital flight of a military vehicle that combines an airplane's agility with a spacecraft's capacity to travel in orbit at 5 miles per second.

At the end of its maiden trip, which could last days or even weeks, the X-37B will glide to Earth under robotic control without the benefit of engines. Instead, it will rely on flight-control surfaces in the tail to steer it through a fiery re-entry, during which the nose and leading edges of the wings must resist 3000-degree-Fahrenheit temperatures. The flight will end in secrecy with a 230-mph touchdown on an isolated runway at an Air Force base in California, most likely Vandenberg.

Though based in many ways on the shuttle-the only operational orbital space plane in the world-the X-37B showcases plenty of innovation. The shuttle uses hydraulic lines to power the control surfaces on its wings and tail, but the X-37B takes advantage of small, powerful electromechanical actuators instead, eliminating the weight of fluid and hoses. In lieu of the ceramic tiles used on the shuttle, the X-37B's leading edges and nose cap are made of an easily shaped composite material that NASA developed when the space agency ran the experimental craft's development, before the military took charge of it in 2004.

The stubby 15-foot wingspan also echoes the shuttle's design, but unlike the larger craft, which has one tall vertical stabilizer, the X-37B has a V-tail with two ruddervators, a combination of a rudder and an elevator. David Hamilton, the director of the Air Force Rapid Capabilities Office, explains that the shorter V-tails are easier to package in a fairing, something that's not a concern for the shuttle. Those V-tails also help guide the X-37B through its 40-degree, nose-high re-entry, while a speed brake along the upper centerline helps it slow down as it prepares to land. Since the X-37B is unmanned, it does not need hardware to maintain a pressurized compartment for a crew and does not have to carry supplies for an extended manned mission.

 The X-37B's simplicity and small size are part of what makes it appealing to the military. "There was always this issue with the space shuttle that you were sending up this enormous truck no matter what you were launching into space," says Mark Lewis, the former chief scientist for the Air Force. "There are times you want the Mack truck and times you want the Volkswagen Beetle. Unfortunately, with the shuttle, you were forced to fly the Mack truck."

The Air Force won't say what the X-37B will do during its first trip to orbit because the program has sunk into the "black" world of classified programs. Until a couple of years ago, the spacecraft was regarded as just another experimental prototype. Today, Air Force officials are skittish to mention even the smallest details. Asked in a recent PM interview what he could say about the X-37B, Werner J.A. Dahm, the Air Force's chief scientist, replied, "Nothing very useful," before quickly changing the subject.

Most of what the Air Force will now publicly acknowledge about the vehicle is contained in an opaquely worded two-page fact sheet: Built by Boeing's secretive Phantom Works division and managed by the Air Force's Rapid Capabilities Office, the X-37B Orbital Test Vehicle "will demonstrate a reliable, reusable, unmanned space test platform for the United States Air Force." Because the program did not start as classified, many of its design details can be gleaned from documents drafted before the program went dark.

The Pentagon's X-37B program stands out at a time when there is a dearth of radical, groundbreaking government-sponsored aircraft and air transportation concepts. "We retired the SR-71," says Vincent Sabathier, a senior associate and space policy specialist at the Center for Strategic and International Studies, based in Washington, D.C., referring to the legendary Blackbird supersonic spyplane. "We will retire the space shuttle. This is something that is still exciting."

Despite decades of work and billions of dollars, the X-37B is the Pentagon's only surviving space plane program after post-Cold War budget cuts. "I think what we had in the last decade was an interruption, or intermission, in space plane development," says Rebecca Grant, a former Air Force official and now the president of the Washington, D.C.-based IRIS Independent Research. "Hopefully now [with the X-37B launch] we're looking at the next act." 

Reusable launch vehicles (RLVs) and space planes have suffered from the promises of scientists and politicians who overestimated their utility and underestimated their complexity. The X-20 Dyna-Soar, a flat-bottom glider that used rockets to take off but made powerless landings, was touted as an unstoppable hypersonic space bomber but was canceled in 1963. Designers billed the quixotic single-stage-to-orbit X-30 as a new Orient Express, leading President Ronald Reagan to say in a 1986 speech that it would be able to "take off from Dulles Airport and accelerate [to] up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within 2 hours." But as the complexities of reusable spacecraft became clearer, the government started cutting space planes from the budget.

NASA took over the development of RLVs from the Pentagon in the 1990s, but critics soon assailed the agency for pursuing endless testbeds rather than operational spacecraft. One of the most ambitious space planes of the era was the X-33, a 69-foot-high craft that did not need a heavy rocket to reach orbit. A test craft was nearly complete in 1999 when engineers discovered cracks in the overweight vehicle's fuel tank. NASA officials canceled the program in 2001, and like nearly all previous space planes, it never flew. "The X-33 required at least one miracle," Lewis says.

In a 2001 congressional hearing, Henry Cooper, the former head of the Strategic Defense Initiative Organization, blamed both NASA and the Air Force for killing space planes: "The Air Force has not been a serious advocate for military space programs-otherwise it would not have supported transferring the reusable launch mission to NASA, an organization that has shown little responsiveness to supporting innovative military space programs."

But civilian space planes did not perform as expected, either. The space shuttle failed to reach its primary goals of making transportation to space cheaper and more efficient. The prospects for a new generation of reusable space planes went from bad to catastrophic when, on Feb. 1, 2003, the space shuttle Columbia broke up during re-entry. NASA's shuttle program, which was originally supposed to carry the X-37 orbital test vehicle, faced an early retirement, and the agency lost interest in RLVs and space planes.

The X-37B, though more modest than its predecessors, seemed to be on a familiar path to extinction. NASA started work on the X-37 in 1999, and soon after, agency officials developed a plan to build an approach and landing test vehicle and an orbital test vehicle. But in 2004 NASA dropped them both. The Defense Department then adopted the X-37 and placed it under the auspices of its research arm, the Defense Advanced Research Projects Agency.

DARPA contracted Burt Rutan's Scaled Composites to conduct drop tests of the X-37 off its White Knight carrier aircraft over California. (The jet-powered White Knight gained fame as the mother ship that launched SpaceShipOne, the suborbital craft that won the Ansari X Prize in 2004.)

In 2006, the X-37 again changed hands, this time going from DARPA to the Air Force, and a cloak of secrecy fell over the program. The new plan focused on building a single orbital test vehicle, rebranded as the X-37B. "I can't say a lot about it," says Lewis, the former Air Force chief scientist. "I had to actually start asking questions about what this thing is, because it was being kept so secret."

The presumption that the space plane's mission is important because it's classified might be a smokescreen, says John Pike, the director of GlobalSecurity.org. "Maybe it's a bad idea," he says. There are reasons for a military program to go "black" that don't have to do with national security.

Secrecy also protects the X-37B and its funding. With tight budgets and skeptics alert for failure, "you put it in the black and you operate it without telling people," Sabathier says. The Air Force declines to disclose how much it's spending on the X-37B, and, because of the classified status, the figure is not otherwise available. 

One very public event may have secured the future of military space planes. On Jan. 11, 2007, China destroyed one of its obsolete weather satellites with a missile ("Battlefield Space," July 2007). Though China's test was hardly a complete surprise to the military or intelligence communities, the incident became a dramatic reminder of the vulnerability of critical satellites.

In an emergency-like a rapidly unfolding crisis or an attack on a vital U.S. satellite-a space plane could become a reconnaissance platform by scanning the Earth below or by observing other objects in orbit. The ability to launch orbital surveillance platforms quickly-what the Pentagon calls "operationally responsive space"-has been a longtime goal of the Defense Department.

"The weird thing to me is that they are being so coy about the types of missions they want space planes to do," says Theresa Hitchens, a space policy expert and director of the United Nations Institute for Disarmament Research. "The first thing that comes to mind is a pop-up reconnaissance vehicle for a place where you don't have satellite reconnaissance or can't move a satellite fast enough."

It can take the Air Force months to prepare a military satellite and days to move one into a new position, compared to about an hour or two to position a space plane kept on alert. Also, any nation with intelligence about U.S. satellite paths can predict when the satellites are overhead, so a space plane offers an element of surprise.

In current conflicts, military commanders have a hard time sharing orbital images because satellites controlled by the National Reconnaissance Office are often tasked to stare at another target. "All the strategic applications are still very appealing if the technology can come together," Grant says.

But if getting satellites into space cheaply is the main goal, then a reusable spacecraft like the X-37B is by no means the best option. Peter Wegner, the director of the Pentagon's Operationally Responsive Space Office, says he's watching advances in RLVs, but his focus instead remains fixed on finding ways to slash the price of expendable rockets. "I think we can hit the [launch] timelines with the expendable vehicles and still cut the cost dramatically," Wegner says.

The most daring job of a space plane, and the one least discussed, is the role of a bomber. The craft could fly over targets within an hour of launch to release cone-shaped re-entry vehicles that would both protect and guide weapons through the atmosphere. A craft the size of the X-37B could carry 1000- or 2000-pound re-entry vehicles armed with precision munitions like bunker-busting penetrators or small-diameter bombs, or simply use the explosive impact of kinetic rods cratering at hypersonic speeds to destroy targets.

However, widespread concerns about stationing weapons in space, possibly starting an orbital arms race with China, could make this option unappealing. In 2001 Boeing pitched a space bomber system to the Pentagon, but there is no evidence that the X-37B is being used to create such a weapon system.

Others in the U.S. government are also expressing interest in the space plane concept. The Pentagon recently completed a document outlining the requirements and development path for a space plane that could insert small teams of Marines anywhere in the world in 2 hours. In February NASA awarded $20 million in research funds to a private space company called Sierra Nevada Corp. to build a passenger space plane called Dream Chaser. The craft would launch on a rocket, ferry up to seven people to the International Space Station (or private space hotels) and then land like the space shuttle. The Air Force's X-37B has the clear lead on these conceptual contenders-Hamilton says the X-37B team is currently preparing for a second launch sometime in 2011.

What may differentiate the X-37B from its predecessors-and what confounds the critics trying to make sense of it-is precisely that its goals don't sound overly futuristic. "I'm more concerned about the programs that are touting themselves about all they will achieve," says Richard Hallion, a former Air Force chief historian and one-time special adviser to the Pentagon on space programs. "The ones that are quiet, the ones that maintain a more modest public posture, we often find have the potential for true greatness."

The X-37B might lack a flashy name, a made-for-the-movies mission and public hoopla, but this space plane's low profile might be just the thing that helps it beat the long odds and become a success.