“In short, the Space Shuttle is so inefficient because it is built upside-down.”--Robert Zubrin
Chapter 1: Preflight
Chapter 1: Preflight
Technicians swarmed around the gleaming white delta-winged shape, mostly around the nose and tail, but some at strategic points along the length, at the engine bays, the landing gear wells, and the control surfaces on the aft side of the wings. The ship’s gleaming white aluminum skin was inspected, with sections yellow or browned with use cleaned and checked. The more resistant titanium armor on the belly, the blunt nose, and the wing leading edges was checked as well. The mighty F-1B engines were inspected and, where needed, swapped out for maintenance. Though they were rated for many more flights, this was to be the highest-profile mission yet in the Space Shuttle program—no one at Boeing or at NASA wanted to take chances now.
Several long gray cables trailed from two boxes embedded into the walls of the flight deck to the hangar floor, where they plugged into a console atop which sat a bulky CRT monitor. Green text on a black background reflected off an engineer’s glasses as he inspected the stored flight data from the last test flight and as his teammates checked that the computer, responsible for the fly-by-wire actuation of the control surfaces, measurement of fuel levels, and the limited life-support capacity of the flight deck, and countless other systems, responded properly to simulated inputs. The comparatively modern IBM AP-101 was a massive leap over the core rope that had graced the Apollo Guidance Computer, and enabled a lot more functions to be off-loaded to the vehicle--and given the flight regime for which it was designed, that was necessary.
Behind an access panel between the LOX tank forward bulkhead and the flight deck hatch, a technician ran a very careful low-power test of one particular circuit, the one that controlled the pyrotechnics that fired the escape pod. A far cry from the launch-abort towers that had protected the Apollo astronauts, but still far better than the ejection seats with which the Gemini crews had had to make do, this system ensured the survival of the crew should the worst happen. This was something the technician was unable to forget, with her supervisor looking over her shoulder at the multimeter in her hand, and with a poster of Snoopy in an orange flight suit reminding her that “Mission success is in YOUR hands!” hanging on the hangar wall. The results checked out, verified by the supervisor with a little help from his pocket calculator--a new model, with an LCD display—as far as they could tell, this system was good to go. The supervisor checked that particular circuit off of the dot-matrix checklist on his clipboard, and they moved on to testing the redundant and triple-redundant back-ups. This particular access point was located near the top of the vehicle--by the light filtering in through open access panels all around, the technician could just make out the yellow-painted bulk of the LOX tank’s forward bulkhead, and the small propellant tanks that fed the separation motors and reaction-control thrusters. Even with those here, the nose of the vehicle was a cavernous void--a vestige of the original design scheme, which had called for the nose to retract back into that void.
Around the hangar, similar inspections ultimately yielded the same results. All five engines were flight-worthy, the control surfaces demonstrated exactly the desired range of motion, the hydraulic actuators that controlled the covers over the jet engines performed as expected, landing gear wheels rotated freely, and the dials on the flight deck were all illuminated perfectly. The last hatches were dogged shut, umbilical cables pulled out, and access ladders wheeled away as an airport tow truck with a bright-red NASA worm on its front and sides rolled in. Pinned securely to the truck, the spacecraft left the fluorescent lighting of the hangar for Florida’s brighter morning sun, the massive American flag painted on each side of her fuselage breaking up her otherwise clean white appearance.
RS-IC-102, “Constitution,” had a date in the VAB.
The transition from a Saturn V first stage to the reusable booster of the Space Transportation System seems obvious and natural in hindsight, almost two decades removed from the birth of either system. However, the Reusable Booster had a much more complex history than many assume, and a close study of the complex origins of the idea illustrates how the most “optimal” design in aerospace can depend on a variety of definitions. Marshall Space Flight Center funded the first studies of what eventually became RS-IC in 1962, with the publication of a study titled “50- to 100-Ton Payload Reusable Orbital Carrier.” Though previous studies had found that retrofitting the S-I stage of the Saturn I and IB with a flexible and deployable wing would be impractical, this study concluded that the much larger S-IC on the Saturn V had more room for improvement. This study envisioned an S-IC modified with landing gear, sharply-swept delta wings with large vertical tips, a flight deck, and modest thermal insulation to protect the booster from the heat of sub-orbital reentry. Boeing developed the design in more detail as the “Model 922,” studying several variants. In the most powerful of these, the Model 922 booster would be paired with an unmodified Saturn V second stage, retaining its full lifting power. This pairing, the Model 922-104, produced a booster that returned the first stage while losing only 20% of its lift capacity. Though these studies were not pursued in the early 1960s (all of NASA’s attention going to getting S-IC and the other parts of the Apollo-Saturn system flying at all), it did plant the first seeds of the flyback first stage in the minds of Marshall and Boeing engineers.
In 1965, Congress began trimming NASA’s budget, which by that point had exceeded $5 billion per year. Smelling a coming storm on the wind, Marshall Space Flight Center and the prime contractors on the Saturn V (Boeing, North American, and Douglas) began studying lower-cost variants of the Saturn system, in order to keep it in service even in the face of future budget cuts. Boeing’s studies were the most wide-ranging, covering Saturn variants from the smallest (~20 tonnes to LEO) to the largest (over 200 tonnes to LEO) capacities. Of most interest to MSFC at the time, however, was Saturn INT-22, a combination of a winged S-IC with a reduced-cost S-IVB to yield a launch vehicle of 45 tonnes capability for a significantly lower cost per-launch than either the Saturn V or Saturn IB. A particularly revolutionary innovation in this study was the concept of “propellant ballasting.” By carrying more propellant than strictly necessary for lower-end payloads, and burning it off in a second post-staging burn of the first stage, reentry velocity could be reduced considerably for smaller payloads (like those needed to service a space station), extending stage life. Indeed, with sufficient ballasting, a payload of 25 tonnes could be delivered with such minimal heating on the booster that the existing aluminum skin of the S-IC would suffice for thermal protection. Though the INT-22 study did not become NASA’s official policy, it was favorably-enough received at MSFC to become the assumed baseline booster for post-Skylab space station programs, and featured prominently in Apollo Extension Series (later Apollo Applications Program) studies.
One should not be fooled by the prominent wings on the INT-22 first stage—this vehicle was not a shuttle, or at least not The Shuttle as that term was understood by NASA in the late 1960s. Shuttle was supposed to be a complete break with the Apollo Program, a fully-reusable, two-stage-to-orbit system propelled by high-thrust staged-combustion hydrogen-burning rocket engines. Even at Boeing and Marshall, this understanding of the plan for the 1970s was inherent in their plans for INT-22—it was to be an interim solution, providing for early Space Stations until Shuttle came into service around 1977. The economic justification for putting wings on the S-IC assumed that the system would be phased out by 1980. When funding for a second run of Saturn components did not materialize by the end of the Johnson Administration, Boeing turned away from INT-22, and instead turned its focus to the two-stage Shuttle. The termination of the Apollo Applications Program and the shifting of focus at NASA from Space Stations to a reusable Space Shuttle in 1969 would have sent INT-22 to join NERVA, X-20, and Project Orion on the heap of space might-have-beens, were it not for a surprise decision by NASA in summer of 1970 to take a second-look at alternative Space Transportation System architectures.
NASA’s Space Shuttle contracting process was divided into four Phases--A, B, C, and D. Phase A consisted of preliminary studies to determine the technical feasibility of an approach to the Shuttle problem. Phase B consisted of detailed studies and preliminary design, while C and D covered test articles and final development, respectively. NASA selected two companies to receive Phase B contracts in May, 1970, North American Rockwell and McDonnell-Douglas, deeming their proposals the strongest. Grumman Chairman Lew Evans, however, raised a massive complaint to Tom Paine’s office, strongly condemning NASA’s preferred Shuttle architecture and blaming Grumman’s loss on weak support from New York’s senators and accusing NASA of playing favorites with North American. Though he was unsuccessful in winning Grumman a Phase B contract at that time (and arguably contributed to the rift that had always existed between Grumman and NASA executives), Evans was persuasive enough, and Grumman’s proposal good enough, for NASA to finance studies of alternative Shuttle architectures. Grumman won the largest of these contracts, but lacked experience with large booster development, and so reached out to Boeing for a collaborative approach.
The Grumman/Boeing proposal differed from the first successful Phase B contracts by incorporating disposable liquid hydrogen tanks. Working in close concert with Max Faget and his team at NASA, Grumman engineers under the direction of Tom Kelly proposed to use disposable, external hydrogen tanks to reduce the weight of the orbiter while at the same time increasing its delta-v capability. This allowed the booster to separate from the orbiter at a lower speed, reducing thermal loading on it and bringing the booster back into the flight regimes studied by Boeing for the INT-22 proposal years earlier. Grumman presented this modified Orbiter design at the Manned Spaceflight Center in Houston in November of 1970. By March of 1971, they had successfully persuaded NASA that their approach was the best, and the agency mandated that the previous Phase B winners, North American Rockwell and McDonnell-Douglas, redesign their Orbiters with external tankage. In May of 1971, working again with Max Faget, Grumman took the next logical step and moved the oxygen tanks out of the Orbiter as well, putting all the Orbiter’s propellant in a disposable, belly-slung aluminum tank. The Booster-Orbiter stack was now somewhat lopsided, as the orbiter hung off the side of the stack, but the numbers didn’t lie--it was as close as NASA had gotten to reaching the peak annual spending cap of $1 billion mandated by the Office of Management and Budget.
Boeing’s management at the time was concerned about the company’s ability to survive the greatest aerospace recession since 1945. Between 1968 and 1971, ¾ of the commercial airplane sector of the company was laid off. These lay-offs rippled across the greater Seattle economy--suburban vacancy rates reached 40%, automobile dealerships collapsed for want of buyers, and so many people fled town that local U-Haul agencies ran out of moving equipment. Two real-estate men in Seattle put up a billboard near the airport, showing a lightbulb hanging on a wire, captioned “Will the last person leaving SEATTLE turn out the lights.” The Boeing 747 was not finding buyers fast enough to cover its development cost, and the US Senate was beginning to move against the Boeing 2707 Supersonic Transport; objections to noise and air pollution by the latter were finding sympathetic Senators in many states not tied to aerospace. The Shuttle became seen by some in Boeing management as critical to keeping the lights on.
By moving the Shuttle Booster’s flight regime back into Boeing’s field of expertise, Grumman offered a way for both companies (for Grumman, too, was suffering from the strain of the F-14 Tomcat program) to save their own skins. By leveraging Grumman’s experience in manned spacecraft and Boeing’s experience in both large supersonic vehicles and large booster development, the two companies hoped to give NASA an unbeatable offer--a Shuttle system more conservative than the main Phase B studies, one easier to develop as it used more off-the-shelf technology, and yet one that still achieved all the payload-servicing, station-resupplying, satellite-deploying objectives NASA wanted in a package that was at least 90%-reusable. It was a match made, so to speak, in heaven, that would allow each company to keep the spacecraft and booster capabilities they’d so painstakingly built up over the past decade--or so it seemed.
The honeymoon ended in late summer of 1971. The Reusable Booster, Reusable-but-with-drop-tanks Orbiter architecture got NASA closer than any other to the OMB’s funding cap--but it still peaked at $1.5 billion per year, half a billion dollars more than OMB would endorse. With the appointment of the new NASA Administrator, James Fletcher, the agency finally accepted that it could not develop the entire Shuttle system at once--the booster and orbiter would have to be developed in a phased development system, one at a time. Though Grumman and Boeing were researching very dissimilar products, they became competitors over scarce funding--NASA would either buy Grumman’s Orbiter, Boeing’s booster, or neither, but it certainly would not buy both at once.
The Space Shuttle Decision, by August of 1971, was reaching its endgame. At this time, on the recommendation of President Nixon’s science advisor, Edward David, a new panel, chaired by Alexander Flax, President of the Pentagon think-tank, Institute for Defense Analysis, was convened to independently analyze the Space Shuttle program. During the summer and autumn of 1971, this panel would meet once a month, meeting with NASA and with the Shuttle contractors. It was during these months that Boeing and Grumman, Marshall Space Flight Center and the Manned Spaceflight Center, would make their own cases to the committee and seek approval for their own preferred option.
EDIT: Author's note, 07/16/2022: Opening quote attributed to Robert Zubrin. The quote appears in "Entering Space," the excerpt from which is given here.