U.S. Space-Launch Vehicle Technology: Viking to Space Shuttle

7. The Space Shuttle, 1972–1991

7 The Space Shuttle, 1972–1991 The space shuttle marked a radical departure from the general pattern of previous launch vehicles. Not only was it, unlike its predecessors, a (mostly) reusable launch vehicle; it was also part spacecraft and part airplane. In the Mercury, Gemini, and Apollo launch vehicles, astronauts had occupied the payload of the rocket, but astronauts on the shuttle rode in and even piloted from a crew compartment in the launch vehicle itself. Also, the shuttle commander landed the orbiter portion of the craft and did so horizontally on a runway. The orbiter had wings like an airplane and set down on landing gear as airplanes do. Indeed, the very concept of the space shuttle came from the idea of airliners, which were not discarded after each mission the way expendable launch vehicles had been but were refurbished, refueled, and used over and over again, greatly reducing the cost of operations. Because of the multifaceted character of the space shuttle, its antecedents are much more diverse than those of the expendable launch vehicles and missiles discussed in Preludes to U.S. Space launch-vehicle Technology and in the rest of this book. Many aspects of the orbiters thus fall outside our scope. This chapter focuses on features most comparable to those of earlier launch vehicles—propulsion, guidance and control, and, to a lesser extent, structure.1 Studies of a reusable launch vehicle date back a long way and continued through the 1960s. But it was not until the early 1970s that budgetary realism forced planners to accept a compromise version of early schemes. In the post-Apollo era, the administration of President Richard M. Nixon faced numerous challenges included the continuing conflict in Vietnam, vociferous antiwar protests, racial unrest, an economic recession, and a budget crisis. While the highly successful but expensive Apollo effort had demonstrated U.S. technological prowess to the world and in some sense defused the Sputnik crisis, the war in Southeast Asia had stimulated a decade of self- U.S. Space-Launch Vehicle Technology 266 criticism in the United States and the rise of a counterculture that rejected the bourgeois values of the 1950s. Although proponents of a fully reusable launch vehicle compared the use of expendable boosters to throwing away an airplane or a railroad locomotive after each trip, in the environment of the early 1970s they had to bow to competing demands for funding and accept a partly reusable vehicle that was cheaper to develop but far less economical to use than they had hoped.2 The NASA budget had already been declining since the mid-1960s, dropping from a high of $5.25 billion in 1965 to $3.75 billion in 1970 and $3.31 billion in 1972 (which, inflation-adjusted to 2006 dollars, would equal $32.98 billion, $19.92 billion, and $15.92 billion). By 1972, both the Air Force and NASA had contracted for a number of studies of space shuttle concepts . In 1968 NASA had introduced a phased project planning approach to research and development in which Phase A comprised advanced studies , Phase B project definition, Phase C actual vehicle design, and Phase D production and operations. The Phase B statement of work in February 1970 called for the shuttle to be a two-stage vehicle that was fully reusable. Then in May 1971 the Office of Management and Budget advised NASA not to expect a budget increase over the next five years. At that time, plans for the fully reusable shuttle showed a development cost of nearly $10 billion with a peak annual cost of about $2 billion. OMB’s funding projection—which proved to be roughly accurate in dollar terms, with an actual decline in real terms—meant that NASA could afford to spend only about $1 billion per year for five years to develop the shuttle and still fund other programs. This grim reality led NASA in the course of 1971–72 to change to a stage-and-ahalf shuttle concept that was only partly reusable.3 For the two-stage shuttle, there had been a fly-back booster and a separate fly-back orbiter. The projected reduction in funding made the fly-back booster too expensive, so gradually NASA and its Phase B contractors, working together, shifted their focus to designs featuring an orbiter with an external propellant tank that would not be recoverable. This cut development costs by permitting the orbiter to be smaller and lighter, but it imposed a penalty...