II. Historical Background–What Were the Shuttle’s
Goals and Possible Configurations?

In 1969, thinking ahead to what NASA would do after the Apollo Moon landings, the president’s Space Task Group, headed by Vice-President Agnew, offered several options involving a human expedition to Mars, lunar and Earth-orbiting space stations, and a reusable space ferry or Shuttle. President Nixon rejected these combinations as too expensive. NASA then decided to push for a Shuttle as a building block for these other goals, especially the space station (Jenkins, p. 64; Logsdon, 1978, pp. 14–15). NASA calculated that the Shuttle would be more popular with Congress and the White House than the other, more expensive options. Nevertheless, in 1971, the Office of Management and Budget (OMB) slashed NASA’s budget, eliminating any growth for the foreseeable future (Logsdon, 1978, pp. 16–17).

OMB and the President’s Science Advisory Committee (PSAC) envisioned the Shuttle as a general workhorse that would take care of the government’s civilian scientific, defense, and intelligence launches, as well as commercial satellite launches. In the early 1970s, analysts projected that military and intelligence satellites would account for 35 percent of future launches (T. Johnson, p. 418). Also at that time, NASA was predicting very high Shuttle launch rates, such as 50 annually² (Barfield, p. 1293). If that held true, the Shuttle could easily handle all U.S. launches in the 1980s and beyond, and so NASA offered to do so (T. Johnson, p. 418).

In 1971, the Air Force, which was responsible for launching all U.S. defense and intelligence satellites, agreed tacitly to support NASA’s Shuttle development program. In effect, the Air Force’s support was only by default, since the Air Force would not contribute funds to Shuttle development but would reap the benefits if NASA’s program worked as promised (T. Johnson, p. 419). Thus the Air Force adopted something of a “wait and see” attitude. Air Force Secretary Robert Seamans, who had been the Associate and Deputy Administrator of NASA during the 1960s, testified before Congress that “I cannot sit here today and say that the space transportation system [the Space Shuttle] is an essential military requirement” (Gillette, p. 394). Despite the Air Force’s lukewarm endorsement, the military’s support for the Shuttle would soon prove important.

One of the primary goals of the Shuttle program was to establish a reusable space transportation system that would lower the cost of access to space. When NASA was developing the hardware to reach the Moon, cost was no object; thus, the Saturn rockets and Apollo spacecraft worked well but were quite expensive. For many years, space enthusiasts had been calling for better access to space, meaning more reliable and less expensive launch vehicles. The simplest way to decrease the cost of space launches would be to make them routine through the use of reusable launch vehicles. Some analysts used the analogy of a railroad that was forced to use a new locomotive after each trip (Launius, 1994, p. 17) to push for a new system. Clearly, it would not be economical for the government or for private industry to launch spacecraft until the cost per pound of launch could be brought down through a reusable system, and NASA wanted the Shuttle to be that system.

Another goal of the Shuttle program was that it would be rated for human spaceflight. This meant a level of reliability and safety beyond that of unpiloted expendable launch vehicles (ELVs). Simply put, if an ELV exploded on the launch pad, a great deal of money and effort would be for naught, but if a space vehicle with people aboard had a serious accident, lives would be lost and the political fallout would be intense.³ The stringent safety requirements for human-rated vehicles meant more extensive testing and different engineering designs, two factors that would increase the cost. Thus, because these first two goals were partially conflicting, there may have been additional pressure for lower costs.

One Air Force requirement that had a critical effect on the Shuttle design was cross range capability. The military wanted to be able to send a Shuttle on an orbit around the Earth’s poles because a significant portion of the Soviet Union was at high latitudes near the Arctic Circle. The idea was to be able to deploy a reconnaissance satellite, retrieve an errant spacecraft, or even capture an enemy satellite, and then have the Shuttle return to its launch site after only one orbit to escape Soviet detection. Because the Earth rotates on its axis, by the time the Shuttle would return to its base, the base would have “moved” approximately 1,100 miles to the east. Thus the Shuttle needed to be able to maneuver that distance “sideways” upon reentering the atmosphere.

Given a choice between straight and delta wings, the latter perform much better in terms of cross range capability. Delta wings produce more lift at hypersonic speeds, enabling more maneuverability (Heppenheimer, p. 220). Given the requirement for cross range capability, a delta-winged vehicle became the clear choice. Additionally, delta-winged vehicles do not heat up as much as straight-winged vehicles during atmospheric reentry (Draper et al., p. 26), thus decreasing the need for expensive and potentially heavy thermal protection systems, although the thermodynamics are too complex to cover fully in this paper. Moreover, some aerodynamicists argued that delta-winged vehicles were a proven technology that provided good balance, stability, and aerodynamic control (Draper et al., pp. 29, 35).

Despite these arguments that eventually prevailed, at least one straight-wing design was prominent for a time, in part because of its designer. Max Faget, the chief engineer at NASA’s Manned Spacecraft Center (later renamed the Johnson Space Center), drew up plans for two straight-winged vehicles—one an orbiter and the other a booster stage—that rode piggyback and were both piloted and fully reusable. Faget had an excellent reputation in the aerospace community, in large measure because of his design of the Mercury “gumdrop”-shaped capsule and because of his work on the Gemini and Apollo spacecraft. Faget argued that his design would enable the orbiter to return to Earth at a sharp angle that would significantly heat only the orbiter’s lower surfaces (Faget, pp. 52–54). Without going into extensive technical detail on the thermal effects of different reentry paths, suffice it to say that Faget’s design was considered for a time largely because of his reputation. Faget acknowledged that his design allowed for a maximum cross range of 230 miles and that to increase this figure, more thermal protection would be needed, which would add precious weight to the vehicle (Faget, p. 59). Given the firm requirement of a greater cross range capability, however, there was ultimately no place for Faget’s straight-wing configuration.

In addition to the Air Force’s cross range demand, the military also wanted a larger Shuttle payload bay than NASA originally advocated. NASA wanted the Shuttle payload bay to accommodate modules for a future space station, which necessitated a payload capacity of approximately 50,000 pounds (Pace, pp. 199, 111). The Air Force wanted a bay 15 x 60 feet that could hold 50,000 to 65,000 pounds and that had doors that could open out into space to deploy satellites easily (Reed, p. 143; Pace, p. 113). This payload requirement meant that the fuselage of the Shuttle needed to be essentially a large rectangular box with rounded surfaces (Reed, p. 143). In general, NASA went with the Air Force’s requirements because it needed the Air Force’s support to help insulate it from the political charge that the Shuttle was really just a step towards human exploration of Mars or a permanent space station (Heppenheimer, pp. 223—224), which is precisely what some people at NASA wanted it to be.

This significant payload bay requirement eliminated a lifting body orbiter configuration from consideration. The aerodynamics of building such a large vehicle without wings were simply too daunting. Lifting bodies also were rejected for another reason: the invention of lightweight tiles that provide thermal protection. This invention meant that an orbiter with delta wings could still be built light enough to be a viable spacecraft (Reed, p. 142). Thus, after the Phase A initial round of configuration selections, NASA rejected lifting body designs (Jenkins, p. 71).

If it weren’t for the payload bay requirement, a lifting body configuration might have worked well. Lifting bodies could have been a good compromise between ballistic capsules and delta- or straight-winged vehicles. They are lighter, have simpler structures, and encounter fewer reentry heating problems than winged vehicles. Lifting bodies have better lift-to-drag ratios than ballistic capsules, which enables them to be piloted more accurately (Peebles, December 1979, p. 487). Lifting bodies had even been considered for the Apollo command modules (Peebles, November 1979, p. 439). Throughout the 1960s and early 1970s, NASA and the Air Force had conducted significant research on various lifting body programs such as the X-23A and the X-24A, demonstrating, among other characteristics, the maneuverability of wingless vehicles (Reed, pp. 129—131, 140).

In fact, Reed argues that the technology existed in 1971 to put a low-cost reusable lifting body as a space orbiter atop the existing Titan III launch vehicle (Reed, p. 140). Moreover, Reed asserts that around this time, when he was an engineer at NASA’s Dryden Flight Research Center, he convinced NASA rocket guru Wernher von Braun of the benefits of putting lifting bodies on von Braun’s proven Saturn launch vehicles as another low-cost reusable method. One of Reed’s superiors at Dryden, Paul Bikle, rejected the idea because Bikle was trained as an aeronautical engineer and felt that this merging of air and space was beyond the scope of his expertise (Reed, pp. 140—141).

Given these four goals of creating a space transportation system that would 1) be reusable and thus lower the cost of accessing space, 2) be safe enough for humans to pilot, 3) have 1,100-mile cross range capability, and 4) have a significant payload capacity, NASA chose a Shuttle with delta wings that seemingly could achieve all these objectives. A straight-winged vehicle would not have sufficient cross range capability. It would be difficult to develop a lifting body vehicle or ballistic capsule with significant payload capacity. So it might seem that NASA’s choice constituted a rational process of elimination. However, this story involves more than an organization acting rationally, so it is worthwhile to consider what social factors may have contributed to NASA’s choice. Before examining the specific circumstances of this case study, however, this paper will turn to a brief overview of some relevant SCOT literature.

²NASA had said that the Shuttle could be used 736 times from 1978 to 1990. Using a more conservative estimate of 566 flights during this 13-year period, that worked out to approximately 44 flights per year. An influential study by the private company Mathematica, Inc., determined that NASA’s development costs would be recovered at such a flight rate. Even such a “conservative” estimate proved to be greatly overstated–in recent years, the Shuttle has only flown six to eight times per year. The Mathematica analysts originally suggested a two-stage, fully reusable Shuttle, but then they concluded that this wasn’t cost-effective and advocated a “one-and-a-half stage Thrust-Assisted Orbiter Shuttle” (Launius 1994, pp. 27–28). This is how the Shuttle is now configured, with partially reusable solid rocket boosters and a non-reusable external fuel tank for the Shuttle’s main engine.

³NASA had already experienced one such galvanizing tragedy on the ground in January 1967, when a fire in an Apollo capsule took the lives of the three astronauts who were inside during tests. After the Shuttle became operational, NASA also experienced the Challenger accident in January 1986.

Updated April 5, 2001
Steven J. Dick, NASA Chief Historian
Steve Garber, NASA History Web Curator
For further information, e-mail histinfo@hq.nasa.gov

Designed by Douglas Ortiz and edited by Lisa Jirousek
NASA Printing and Design