USAF To Launch First Spaceplane DemonstratorAug 3, 2008
By Craig Covault
The Air Force is preparing for the Atlas V launch in December of the first U.S. robotic military spaceplane mission into orbit.
The X-37B Orbital Test Vehicle flight will mark a fundamental technology milestone for the Air Force. It will carry on winged hypersonic space vehicle technology as the space shuttle is canceled. This work is designed to propel the Air Force mission more rapidly - to where the blue sky turns to black - using a reusable hypersonic craft serviced on the ground just like an airplane.
In the future, this could lead to military spaceplane capability for the same kind of rapid access to the blackness of space that the Air Force already has to the blue sky - for the same offensive and defensive missions, including intelligence, strike and communications services to the military as a whole.
The 11,000-lb. Boeing Phantom Works vehicle is about 29 ft. long with a roughly 15-ft. wingspan; the vehicle height is 9.6 ft. Its 205-ft.-tall Atlas V 501 booster will lift off from Launch Complex 41 here on 1 million lb. thrust. The 501 version with no solid rocket motors can carry up to 10.6 tons to low Earth orbit. The orbital test vehicle will be carried under a shroud on the United Launch Alliance booster.
Once in orbit, the spacecraft will open a small payload bay and deploy a gallium arsenide solar array to power its flight. The exact mission duration is classified.
The X-37B is designed for multiple missions, moving X-plane flight testing into space from the ground.
A landing is planned at the space shuttle runway at Vandenberg AFB, Calif., according to U.S. Air Force Lt. Col. Mark W. Brown in the Office of the Secretary of Defense. Touchdown should occur after some weeks in orbit demonstrating the new computational and other technologies of the Space Maneuvering Vehicle (SMV). The shuttle runway at Edwards AFB, Calif., could be an alternate landing site.
The touchdown will involve a steep 20-deg., 170-190-kt. diving shuttle-type approach similar to that used in helicopter drop tests with a subscale X-40 vehicle and the more complex X-37A.
The X-37B is to test advanced thermal protection materials, autonomous approach and landing schemes, and orbital and ground operations.
The U.S. Air Force Space Command and the Defense Advanced Research Projects Agency will control the flight. The project was taken over by Darpa when NASA dropped its collaboration with the Air Force in 2004 after the space agency determined that it was much more a military than a joint civil/military endeavor. The NASA Marshall Space Flight Center, however, has done extensive work on the program.
The X-37B will use advanced thermal protection tiles and carbon-carbon materials to protect its carbon composite and aluminum skin during reentry. The vehicle has as a nitrogen tetroxide/hydrazine propulsion system with a robust propellant load for maneuvering in space and for the deorbit burn. A more cutting-edge Aerojet kerosene/hydrogen peroxide system developed initially for the vehicle was dropped for use on the first flight, but it could fly on later missions.
The mission will use an Atlas V Eastern Range slot that had been reserved for the launch of NASA's Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite. That flight is now slated for February-March 2009 (AW&ST July 28, p. 30).
Research conducted at the Air Force Institute of Technology at Wright-Patterson AFB, Ohio, shows that an operational SMV would support the Air Force Space Command Strategic Master Plan prepared in 2000. The research found that it would have "direct and substantial" effect on four of the top 10 Space Command priorities in the near term and six in the mid-term. Those priorities include:
* Intelligence, surveillance and reconnaissance of ground targets with either integrated sensors or deployed surveillance satellites.
* Deployment of Space Control Microsatellites for key surveillance and intelligence missions in a crisis.
* Rapid replenishment of constellations by the small satellites that could be carried in an SMV payload bay.
Unclassified tests of X-40 and X-37A atmospheric flight test versions of the vehicle have been underway for years at Edwards AFB and Holloman AFB, N.M.
More recently, drops from the Scaled Composites WhiteKnightOne carrier aircraft for SpaceShipOne have been part of those evaluations.
The X-37's shape is a 120% scale derivative of the X-40A, also designed and built by Boeing; X-40 drop tests began in 1998.
The X-40A - which lacks the X-37's advanced thermal protection materials, rocket engine, experiment bay and other spacecraft systems - was released from a U.S. Army Chinook helicopter in a series of free-flight tests in 2001 to reduce technical risk before testing the X-37A from a CH-47. During drops, the X-37A made complex maneuvers such as pitch, roll and yaw adjustments when the nose was raised, rotated and moved side to side in flight.
It's noteworthy that as the space shuttle is being phased out, X-37B work will continue in space using a winged reusable vehicle that, operationally, would also be equipped with a payload bay. Those attributes - wings for a gliding reentry and horizontal landing, coupled with a payload bay that can be reconfigured for diverse operations - are something that no traditional satellite can provide.
The U.S. flight comes after 50 years of USAF spaceplane research. That work goes back to the manned, winged USAF Dyna-Soar program (that never flew), but preceded even the NASA Project Mercury ballistic capsule in its design.
Neil Armstrong - who was an X-15 pilot, then astronaut commanding Apollo 11 to the first manned landing on the Moon - was selected initially as a Dyna-Soar pilot before he shifted to NASA in 1962.
Until now, the inability of the Air Force to conduct spaceplane tests in orbit, let alone field an operational vehicle, stems back to compromises with NASA over the shuttle development that began 35 years ago. The situation also involves new U.S. national space policy, which has now swung much more in favor of military space.
Ironically, a space shuttle "drop test" of the X-37B had been planned for 2006 but was canceled after the Columbia accident in 2003. The growing military capability in space, however, posed by China, India, Israel and eventually even Iran has helped to keep up momentum in new space-access and counterspace programs.
The X-37B like the shuttle uses a double delta wing, and the vehicle will use shuttle aerodynamic reentry algorithms.
Whether more than one X-37B flight takes place is yet to be determined. But later tests by it or related vehicles, as well as continued technology development, could give the Pentagon a new foothold in space for more diverse robotic military operations.
Unlike the shuttle, operational spaceplane versions would be relatively small and always flown on expendable launch vehicles or larger spaceplane carriers. A rapid access to space and low cost are two other important objectives the shuttle was never able to provide. Robotic operations, as opposed to manned flights, will be a key to lower cost.
The uniquely shaped vehicle is an innovative approach to fulfilling an Air Force need for a new generation of small and reusable, highly maneuverable space vehicles to perform a variety of tasks. It is designed for quick turnaround - 72 hr. or less between missions - and it can remain on station for up to one year.
Boeing Phantom Works developed the SMV demonstrator under the direction of the U.S. Air Force Research LaboratoryýýýMilitary Spaceplane Technology program at Kirtland AFB, N.M., and the Air Vehicle Directorate at Wright-Patterson AFB, Ohio.
During 1969-88, the Soviet Union conducted five flight tests of a robotic military spaceplane prior to a single robotic flight later in 1988 of its much larger Buran shuttle intended for manned operations. Four of the Soviet "Bor" spaceplane tests, all launched by an expendable booster, were successful.
All were lifting-body wing designs except one with the double delta wing of Buran to validate its hypersonic aerodynamics.
Source
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