Historical BackgroundWhat Were the Shuttles
Goals and Possible Configurations?
1969, thinking ahead to what NASA would do after the Apollo Moon
landings, the presidents 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. 1415). 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 NASAs budget, eliminating
any growth for the foreseeable future (Logsdon, 1978, pp. 1617).
and the Presidents Science Advisory Committee (PSAC) envisioned
the Shuttle as a general workhorse that would take care of the governments
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).
1971, the Air Force, which was responsible for launching all U.S.
defense and intelligence satellites, agreed tacitly to support NASAs
Shuttle development program. In effect, the Air Forces support
was only by default, since the Air Force would not contribute funds
to Shuttle development but would reap the benefits if NASAs
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 Forces lukewarm endorsement,
the militarys support for the Shuttle would soon prove important.
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.
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.
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 Earths 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.
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).
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 NASAs Manned Spacecraft Center
(later renamed the Johnson Space Center), drew up plans for two
straight-winged vehiclesone an orbiter and the other a booster
stagethat 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
orbiters lower surfaces (Faget, pp. 5254). Without going
into extensive technical detail on the thermal effects of different
reentry paths, suffice it to say that Fagets 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 Fagets straight-wing configuration.
addition to the Air Forces 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 Forces requirements because it needed the Air Forces
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. 223224), which is precisely
what some people at NASA wanted it to be.
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).
it werent 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. 129131, 140).
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 NASAs Dryden Flight
Research Center, he convinced NASA rocket guru Wernher von Braun
of the benefits of putting lifting bodies on von Brauns proven
Saturn launch vehicles as another low-cost reusable method. One
of Reeds 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. 140141).
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 NASAs 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 NASAs choice.
Before examining the specific circumstances of this case study,
however, this paper will turn to a brief overview of some relevant
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 NASAs development costs would be recovered at such a
flight rate. Even such a conservative estimate proved
to be greatly overstatedin 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 wasnt cost-effective and advocated a one-and-a-half
stage Thrust-Assisted Orbiter Shuttle (Launius 1994, pp. 2728).
This is how the Shuttle is now configured, with partially reusable
solid rocket boosters and a non-reusable external fuel tank for
the Shuttles main engine.
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.
April 5, 2001
Steven J. Dick, NASA Chief Historian
Steve Garber, NASA History Web Curator
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