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"  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&amp;#039;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&amp;#039;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&amp;#039;s agility with a spacecraft&amp;#039;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&amp;#039;s leading edges and nose capare made of an easily shaped composite material that NASA developed when the space agency ran the experimental craft&amp;#039;s development, before the military took charge of it in 2004.  The stubby 15-foot wingspan also echoes the shuttle&amp;#039;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&amp;#039;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.         Click to Enlarge     The X-37B&amp;#039;s simplicity and small size are part of what makes it appealing to the military. &amp;quot;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,&amp;quot; says Mark Lewis, the former chief scientist for the Air Force. &amp;quot;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.&amp;quot;  The Air Force won&amp;#039;t say what the X-37B will do during its first trip to orbit because the program has sunk into the &amp;quot;black&amp;quot; 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&amp;#039;s chief scientist, replied, &amp;quot;Nothing very useful,&amp;quot; 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&amp;#039;s secretive Phantom Works division and managed by the Air Force&amp;#039;s Rapid Capabilities Office, the X-37B Orbital Test Vehicle &amp;quot;will demonstrate a reliable, reusable, unmanned space test platform for the United States Air Force.&amp;quot; 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&amp;#039;s X-37B program stands out at a time when there is a dearth of radical, groundbreaking government-sponsored aircraft and air transportation concepts. &amp;quot;We retired the SR-71,&amp;quot; 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. &amp;quot;We will retire the space shuttle. This is something that is still exciting.&amp;quot; Despite decades of work and billions of dollars, the X-37B is the Pentagon&amp;#039;s only surviving space plane program after post-Cold War budget cuts. &amp;quot;I think what we had in the last decade was an interruption, or intermission, in space plane development,&amp;quot; says Rebecca Grant, a former Air Force official and now the president of the Washington, D.C.-based IRIS Independent Research. &amp;quot;Hopefully now [with the X-37B launch] we&amp;#039;re looking at the next act.&amp;quot;  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 &amp;quot;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.&amp;quot; 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&amp;#039;s fuel tank. NASA officials canceled the program in 2001, and like nearly all previous space planes, it never flew. &amp;quot;The X-33 required at least one miracle,&amp;quot; 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: &amp;quot;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.&amp;quot;  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&amp;#039;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&amp;#039;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. &amp;quot;I can&amp;#039;t say a lot about it,&amp;quot; says Lewis, the former Air Force chief scientist. &amp;quot;I had to actually start asking questions about what this thing is, because it was being kept so secret.&amp;quot;  The presumption that the space plane&amp;#039;s mission is important because it&amp;#039;s classified might be a smokescreen, says John Pike, the director of GlobalSecurity.org. &amp;quot;Maybe it&amp;#039;s a bad idea,&amp;quot; he says. There are reasons for a military program to go &amp;quot;black&amp;quot; that don&amp;#039;t have to do with national security. Secrecy also protects the X-37B and its funding. With tight budgets and skeptics alert for failure, &amp;quot;you put it in the black and you operate it without telling people,&amp;quot; Sabathier says. The Air Force declines to disclose how much it&amp;#039;s spending on the X-37B, and, because of the classified status, the figure is not otherwise available. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/space/a5448/behind-the-air-forces-secret-robotic-space-plane/>