Is the Spaceplane Dead?

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The Air Force has pursued this concept for the past 40 years. Is the Spaceplane Dead?

SPACEPLANE has been part Ideas for a spaceplane date back By Rebecca Grant of the Air Force’s long- to German research on rocketry be- A range vision for more than fore World War II. In the Air Force, 40 years. Advocates say a reusable a reusable spaceplane has long been spaceplane could cut launch costs part of the vision for full control and from $10,000 per pound of cargo to exploitation of air and space. $1,000 per pound and give the Air Force much greater flexibility in Schriever’s Vision access to space, whether for main- In 1962, Gen. Bernard A. Schriever taining satellites or performing other described a set of requirements for missions. space capabilities that included the It would also provide the ultimate ability to orbit, maneuver, rendez- counter to any adversary’s anti-ac- vous, de-orbit, re-enter, and land on cess strategies; a spaceplane that can a routine basis. Today, USAF is still fly at Mach 25, reach orbit, and re- at least a decade away from acquir- turn to Earth would be virtually im- ing a reusable spaceplane that can possible to stop before reaching its do the jobs Schriever described. objective. Technology hurdles remain at the But today, there is no single heart of the issue. Hypersonic flight— “spaceplane” on the drawing boards. defined as flying faster than Mach Several experimental vehicles are 5—began to tantalize aerospace en- seeking to demonstrate the technolo- gineers in the 1950s. One early suc- gies needed for a spaceplane. A De- cess was the North American X-15, cember 2000 report from the Air tested at speeds up to Mach 6.7 in the Force’s Scientific Advisory Board 1960s. But for the most part, pro- laid it out: “If the Air Force vision of grams dealing in hypersonics and ‘controlling and exploiting the full reusable spaceflight made only lim- aerospace continuum’ is to become ited progress. One such was the reality, the Air Force needs a com- Boeing X-20 Dyna-Soar, a boost- prehensive plan for hypersonics.” glide vehicle designed to become a Yet the Air Force has been sty- manned, orbital plane. The Air Force mied in its efforts to get Washington funded it in 1957, but Secretary of behind a stated requirement for a Defense Robert S. McNamara can- spaceplane or to fund the extensive celed the X-20 in 1963, and Phase 1 research that is still needed to make of the hypersonic spaceplane era was the concept a reality. The recent de- over. mise of the X-33 spaceplane project Dyna-Soar and other programs signaled that once again, the tech- contributed to the manned space nology hurdle is high and the gap shuttle program. NASA’s space between dollars and rhetoric is deep. shuttle first flew in April 1981 and

68 AIR FORCE Magazine / November 2001 truck and a strike platform, the spaceplane would be a revolutionary leap.

No “Golden Mission” However, research on NASP stalled when it failed to meet performance goals. By the early 1990s, NASP was projected to be a decade late and 500 percent over budget. NASP was “fully capable of hypersonic flight,” according to the Science Advisory Board, but could not reach orbital velocity. Advanced hypersonic technology remained out of reach. “On the basis of current knowledge, it is hard to defend previous DOD plans for NASP,” concluded a RAND report in 1989. “No compelling ‘golden mission’ exists for NASP.” Cuts in the defense budget and the The quest for hypersonics and reusable spaceflight led in 1957 to the Dyna- end of the Cold War sealed the fate Soar X-20. It was designed to be a manned orbital craft and did contribute to of NASP and the program was can- the space shuttle program but was canceled in 1963. (Artist’s concept) celed in 1994. “These are exciting ideas,” said Martin Faga, assistant has logged more than 100 successful As a result, the National Aero- secretary of the Air Force for space missions, sometimes flying on a space Plane was to be a revolution- at the time, “but they are not ready monthly basis. Still, the shuttle’s need ary advance: a transatmospheric craft for commitment.” for expendable tanks to help it reach that would provide cheaper space Even before the death of NASP, orbit and the continued high cost of launch and the ability to exploit space researchers were focusing on a more each launch differed from the con- in military operations. Plans called cautious approach that divided up cept of a true spaceplane. Better ac- for NASP to fly as a single stage to the technology hurdles of hypersonic cess to space continued to be a driv- low Earth orbit and to cruise at hy- flight and reusable systems. ing issue. personic speeds of Mach 12 to The next “spaceplane experimen- In 1986, President Reagan rein- Mach 25 in the transatmosphere— tal” was an early success that raised vigorated the idea of an airplane- between the altitudes of 100,000 to hopes for both military and commer- like transatmospheric spaceplane. In 350,000 feet. cial applications for a spaceplane. 1986, he called for “a new Orient With the advent of NASP, the McDonnell Douglas won a contract in Express” that could, by the end of spaceplane concept branched into two 1991 to build what became the DC-X the 1990s, “take off from Dulles roles. Delta Clipper. This single-stage-to- Airport and accelerate up to 25 times First, a reusable spaceplane might orbit vehicle grew out of an SDI re- the speed of sound.” In Reagan’s replace the space shuttle as a launch quirement for a single-stage, reusable concept the transatmospheric plane platform carrying heavy payloads for vehicle that could put Brilliant Pebbles, could attain low Earth orbit or stay customers like the Strategic Defense a component of a ballistic missile de- in the atmosphere, “flying to Tokyo Initiative Organization, which con- fense system, into orbit at a reason- within two hours.” tributed heavily to NASP research able price. It was managed by the Air Behind Reagan’s sensational an- funding. Air Force Brig. Gen. Ken- Force for SDIO, later the Ballistic nouncement was hope for a techno- neth E. Staten, NASP program man- Missile Defense Organization. logical breakthrough in the field of ager, said in 1986 that NASP might Although the program was handed hypersonics. Research from a De- be able to deliver payloads to orbit off to NASA, the Delta Clipper stirred fense Advanced Research Projects for “between one percent and 25 Air Force thinking on the possible AgencyÐfunded secret program called percent of the expense of doing it uses of a spaceplane. The commer- Copper Canyon suggested that ac- with the shuttle.” cial potential and simplicity of the tive thermal management could boost Second, for the Air Force, NASP program seemed to foreshadow a new the power of a scramjet engine. In- could also be a lightning-fast bomber. era when commercial launch demand stead of succumbing to a heat barrier Gen. Lawrence A. Skantze in 1985, would help fund spaceplane tech- around Mach 8, the friction from the as commander of Air Force Systems nologies. atmospheric drag would be used as Command, said NASP might have The Delta Clipper was not a hy- part of a system to superheat hydro- “the speed of response of an ICBM personic scramjet spaceplane but a gen fuel then inject it into a scramjet and the flexibility and reliability of single-stage rocket with advanced engine. Using this technique, a space- a bomber, packaged together in a lightweight materials and directional plane might overcome the thermal plane that can scramble, get into or- control. Its charter was to demon- drag barrier by dissipating heat, while bit, and change orbit so [that] the strate the ability to take off and land using the energy to boost engine per- Soviets can’t get a reading accurate vertically, using controlled, rocket- formance. enough to shoot at it.” As a satellite powered flight. In its full concept,

AIR FORCE Magazine / November 2001 69 the Clipper would be a reusable ve- All programs shared the same phi- space shuttle program. The linear hicle that could be launched and re- losophy: rapid development of proto- aerospike was designed to increase covered at the same site by a small types, with no more than a few years power and, more importantly, per- ground control team. Maintenance passing between contract award and form with maximum efficiency at a would be streamlined, leading to demonstration. Some, like Boeing’s greater range of altitudes. lower operating and support costs X-37 and X-40, were demonstrators Test of the linear aerospike en- that would bring about a dramatic for a vehicle that would be ferried into gines proceeded smoothly through a reduction in the price of launching orbit, operated by its own rocket en- series of test runs in 2000. The payloads into orbit. The subscale gine, then would return to land on a aerospike engine project manager, demonstrator and an advanced ver- runway. In contrast, Lockheed Martin’s Donald Chenevert, praised the per- sion, the DC-XA, successfully com- X-33 was designed to take off verti- formance of the engines, noting that pleted a series of flights in the pe- cally, fly a suborbital path, and then “few new, much less innovative, riod 1993Ð96, demonstrating control land horizontally at a US base. Orbital engines even get to full power in so and maneuverability at the White Sciences’ X-34 was a rocketplane de- few tests,” but with X-33’s engines, Sands Missile Range in New Mexico. signed to be launched from a jetliner, “we met or exceeded a number of Then trouble struck. During land- reach Mach 8, then return and land on significant objectives during the first ing on July 31, 1996, a landing strut a runway. X-43A, also from Orbital phase of the program.” failed to extend. The Clipper tipped Sciences, was built to ride into the air X-33’s big test was to be a series over and its liquid oxygen tank ex- on a B-52 bomber, separate from the of suborbital “hops” where the dem- ploded, causing a fire that destroyed bomber, then from a boost rocket, and onstrator would take off, fly to an- the vehicle. “Like any good experi- fly a Mach 10 trajectory before crash- other point, and land. But the hops mental vehicle, the DC-XA flew un- landing in the Pacific. never took place. X-33 suffered a til it was destroyed,” commented Mc- The Air Force was a junior part- setback in a November 1999 test, Donnell Douglas. “We will always ner in deals with NASA and aero- when the composite material layers be impressed by the lessons this little space industrial firms to fund these of a liquid hydrogen fuel tank peeled rocket taught us.” X-planes. For example, the X-37 pro- apart during a stress test. An agree- gram was financed by roughly $75 ment signed in the fall of 2000 kept NASA’s X-Planes million from Boeing, $72 million work going on X-33 until March During the 1990s, NASA took the from NASA, and just $16 million 2001. However, the delays caused lead in research on spaceplane tech- from the Air Force. by the fuel tank problems slowed nologies. No single program was at- Despite its limited financial par- work on X-33, so it never picked up tempting to pair single-stage launch ticipation, the Air Force closely momentum to become a priority for to orbit with hypersonic transat- watched the X-planes. X-33, in par- NASA, where many regarded the mospheric flight. Instead, a series of ticular, looked like it could push the single-stage-to-orbit concept as too X-planes sought to test various as- envelope on spaceplane design and difficult. NASA canceled the $1.3 pects of spaceplane operations, rang- give the Air Force a chance to evalu- billion program in March 2001. “We ing from thermal material to advanced ate suborbital space operations con- are going to take off our silk scarves propulsion to autonomous landing cepts. X-33’s linear aerospike en- and retire them for a while,” said under different weather conditions, gines were a significant evolution Daniel Goldin, NASA administra- but not a full-scale demonstration. from the bell-shaped engines of the tor, in a Washington Post interview. NASA’s cancellation of X-33 set up the first major challenge for the Air Force’s decade-long practice of letting NASA take the lead in spaceplane development. The commander of Air Force Space Command, Gen. Ralph E. Eberhart, wrote to Goldin and said that the Air Force wanted to review the situation and perhaps take over support of the X-33 program. Estimates for completing the proto- type X-33 ran to about $400 million, while developing and testing a full- scale spaceplane force might cost between $3 billion and $7 billion by 2015. However, Samuel L. Venneri, a top NASA technology official, told the Washington Post, “We’re not in- terested in spending any additional money out of our technology pro- Stress tests on X-33 caused the composite layers of the liquid hydrogen fuel gram, if it is not associated with a tank to peel apart. Here, in 1998, the first major element placed in X-33’s strong commitment from the Air assembly fixture was a tank for liquid oxygen. NASA canceled X-33 in March. Force.”

70 AIR FORCE Magazine / November 2001 For the Air Force, X-33 raised important questions. To begin with, as the SAB concluded, USAF needed a reusable spaceplane because it was “unlikely that the Air Force will ever be able to achieve an aggressive aerospace force vision by relying on [expendable launch vehicles] for its access to space.” Indeed, spaceplane concepts had become a central part of the Air Force’s vision of its future. Long-range plans written by Air Force Space Command and by the Directorate of Strategic Planning at USAF headquarters both called for a new generation of reusable space vehicles to provide space control, including assured launch capabilities, surveillance, protection of assets in space, and the prevention of hostile operations. If necessary, space The second free flight of X-40A, an 85 percent scale version of the proposed control would extend to negation: us- X-37, took place earlier this year at Edwards. The unmanned X-37 was to be ing military force against an enemy’s used as a test bed for some Space Maneuvering Vehicle concepts. space capability. Air Force plans envisaged acquisi- operations,” said retired Lt. Gen. flict arose, the spaceplane could “send tion of a Space Operating Vehicle Marvin R. Esmond, a former deputy a message right from Vandenberg [Air and a Space Maneuvering Vehicle. chief of staff for air and space opera- Force Base in California] in less than The Space Operating Vehicle would tions. A suborbital craft—flying at an hour,” said Esmond. Compared with be a single-stage-to-orbit vehicle that Mach 10 or 12 instead of the full the B-2 bomber’s average 17-hour one- could launch to low Earth orbit or Mach 25 needed to reach orbit—could way flight time to its targets during employ a second, pop-up stage to put evolve into the next long-range strike the Kosovo crisis, a suborbital strike payloads into medium Earth orbit or aircraft. As the SAB said, “The press- craft would seem to be almost instan- beyond. The SOV would launch ver- ing utility for a hypersonic aircraft is taneous. It would transform the aero- tically on demand, deliver payloads rapid time-to-target, the survivabil- space force. or conduct surveillance or any other ity provided by increased speed, some At the end of the summer, Air type of combat support mission, and loiter and search capability, and in- Force Space Command briefed Air return to Earth and land horizontally. creased weapon penetration and kill Force Secretary James Roche on its The Space Maneuvering Vehicle would capability.” $2 billion proposal to keep X-33 alive be an on-orbit vehicle that might per- If the X-33 suborbital hops worked, and to extend funding of Boeing’s form missions after being launched it could have demonstrated the con- X-37 beyond 2002. “My feeling was, by a reusable launch vehicle or a cept of operations for a suborbital, it’s expensive, but you don’t know Space Operating Vehicle. The Space hypersonic strike platform which until you try,” Esmond said of X-33. Maneuvering Vehicle could act as a would make the most of swiftness “This had, to date, the best chance of temporary satellite itself or maneu- and increased survivability and per- success.” ver to perform missions such as de- haps replace long-range bombers. For However, the plan fell victim to ploying or retrieving satellites. Ac- example, a suborbital vehicle could budget constraints. “Both programs cording to USAF officials, it would launch rapidly, reach speeds high have made significant contributions stay in orbit for four to six months, enough to travel to the upper edges toward understanding achievable carrying anything from weapons to of the atmosphere, then launch weap- vehicle performance, cost, and inte- replacement satellites. ons, all while remaining over the gration issues and have provided X-33 tested some of the technolo- sovereign territory of the United valuable information on the dynam- gies that might be used in a follow- States or open oceans. ics of launching space vehicles,” the on Space Operating Vehicle, and In that sense, the spaceplane would Air Force said officially on Sept. 7, X-37 (X-40A) prototyped some of be the ultimate anti-access weapon, 2001. Neither X-33 nor X-37 pro- the concepts for a Space Maneuver- requiring no diplomatic overflight vided “a level of military utility ing Vehicle. clearances and no serious threat of needed to continue development and opposition. A spaceplane could travel funding by the Air Force.” Serious Ops ... On Demand so high and fast that it would be well The X-33 decision was a surprise, However, the planned X-33 dem- beyond the tracking abilities of cur- not the least because it came after onstrations also rekindled Air Force rent surface-to-air missiles. Hypersonic the Air Force had declared a renewed interest in the spaceplane’s potential. velocity would increase the depth of focus on the development of mili- Senior leaders saw in it the capability weapons impact, enhancing the Air tary space power. A spaceplane with “to do serious operations in space on Force’s capabilities for attacking hard- responsive capabilities to replenish demand—from space control to space ened and deeply buried targets. If con- satellites could be the most useful

AIR FORCE Magazine / November 2001 71 The Air Force’s Scientific Advisory Board concluded in its December 2000 report that the demand for reusable space access would grow as USAF became “a true aerospace force.” Even so, the bulk of the techni- cians who have experience in hypersonic experimentation—not just theory—is aging rapidly. According to the Scientific Advisory Board, “The hypersonics workforce is at a crossroads,” and “the majority of its members will retire in the next five to 10 years.” Foreign competition may also emerge. Russia, China, France, India, Germany, and several other nations are working diligently on hypersonics. In fact, the Air Force Research Lab, headquartered at WrightÐPatterson AFB, Ohio, and An artist’s concept of Lockheed Martin’s VentureStar, a single-stage-to-orbit its Office of Scientific Research in reusable vehicle to be derived from X-33, shows the vehicle releasing a satel- Arlington, Va., have funded joint lite into orbit. USAF’s recent decision not to fund X-33 came as a surprise. research with Russian agencies. If their research bears fruit, the United item in the inventory in the event of for the next 50 years. Why penetrate States could find itself behind the a “space Pearl Harbor” that takes out with a bomber when the weapon could pack and on the wrong side of an on-orbit systems. be delivered from a suborbital space- asymmetric capability. Even in a less catastrophic sce- craft?” A spaceplane could carry out Most of all, the spaceplane re- nario, a spaceplane seemed to offer immediate attack operations against mains a good fulfillment of long- the potential for real transformation targets harboring weapons of mass term Air Force requirements. Ex- of US forces over time. In the near destruction, for example. pendable launch vehicles will not term, X-33 “would have given us the meet future demand for space ac- vehicle behind which to have a seri- The Saga Continues cess. Even a suborbital spaceplane ous discussion” on doctrinal and As illustrated by the demise of the could also serve the demands of ex- political aspects of joint space op- X-33 program, the path toward a peditionary operations and homeland erations, explained Esmond. In the spaceplane remains difficult, and security more efficiently in several long term, spaceplanes serving as constant demands on USAF aero- roles. According to the SAB, reus- strike platforms could change the space power will make it hard to find able launch vehicles like the X-33 equation of US defense planning by significant streams of investment concept “offer immense potential to making it possible to launch flex- needed to develop the technologies. meet all the requirements of the fu- ible, rapid strike missions from But given its central role in the Air ture US aerospace force.” Combin- United States territory. Force vision, the spaceplane con- ing hypersonics and a reliable, reus- “I think it’s truly the answer [for] cept is not finished yet. “With Rums- able platform is the path to dramatic full global reach, global power,” said feld, who understands space, and this improvement in the Air Force’s core Esmond. A fully developed, subor- Administration, which is excited competencies. bital, hypersonic spaceplane could about transformation and becoming With a suborbital hypersonic craft ultimately “stand on alert and pro- more efficient, we are closer than or one that can reach orbit, USAF vide a deterrent force. Then you could ever,” Esmond said. would gain a rapid-response capa- shape the Air Force to be truly expe- The choice about when to push bility of phenomenal power, free of ditionary and take care of smaller- hard for a reusable, hypersonic space- much of the infrastructure needed scale contingencies,” he added. plane cannot be put off indefinitely. for expeditionary warfare. To be sure, Critics contend that today’s fight- “As with air operations, the Air an Air Force base would have to be ers and bombers can, for vastly less Force must take steps to create a cul- heavily modified with a new ground cost, do the job of a fleet of space- ture within the service dedicated to support structure to accommodate planes. True, the initial cost of field- developing new space system con- spaceplanes, but the asymmetric ca- ing a spaceplane would be extremely cepts, doctrine, and operational capabilities of a spaceplane would high. However, revolutions do not pabilities,” said the Rumsfeld Space trump all remnants of 20th century come cheap. Total investment to date Commission Report in January 2001. warfare. ■ in stealth aircraft programs exceeds $100 billion. Rebecca Grant is president of IRIS Independent Research in Washington, More to the point, said one Air D.C., and has worked for RAND, the Secretary of the Air Force, and the Chief Force official, is this question: “How of Staff of the Air Force. Grant is a fellow of the Eaker Institute for Aerospace Concepts, the public policy and research arm of the Air Force Association’s long can we penetrate [enemy air Aerospace Education Foundation. Her most recent article, “Altitude,” ap- defenses] with stealth? It won’t last peared in the October 2001 issue.

72 AIR FORCE Magazine / November 2001