“If you have a 65,000-lb manned scientific laboratory to place in low Earth orbit, then the Lifter is just the job. But if you have a 1,000-lb communications satellite bound for stationary orbit (and paid for by the shareholders), a good old-fashioned rocket will do the job at half the cost.”
Chapter 7: Max-Q
Twenty seconds after liftoff, the stack climbed into the skies above Florida. As the delta-winged stack climbed, the Earth made one last effort to hold it back. Its own speed now conspired against it. As the rocket pushed its way through Earth’s thick atmosphere, breaking the speed of sound and leaving its own roar behind, it squeezed the air in front of it far above ambient pressure. Constitution’s five F-1B engines automatically throttled back as the stack approached the region where the atmosphere and its speed would produce Max-Q: the peak of aerodynamic stresses on the rocket. Throttling back slowed the ascent, introducing losses just as drag increased, but the larger worry was the forces on the Lifter and the Orbiter as the dynamic pressure climbed to more than three times that at sea level. The stack shook as the atmosphere buffeted the rocket.
The pressure was intense, and every eye at mission control watched the data for any sign of failure in these critical moments. As the stack pushed closer to Max-Q, the pressure was enough to condense water from vapor to liquid, forming opaque discs around the base of the Orbiter and alongside its control surfaces. Briefly, the Orbiter once again vanished from the Lifter crew’s view as a cloud developed around its base, around the complex interface between its aft end and the S-IVC. For the complete Space Transportation System, this was a moment of truth: would the models developed in aerodynamic trials on the ground hold through the test of reality?
The pressure data in the telemetry and the gauges of the stack’s two cockpits climbed, then steadied...and then finally began to drop. The shock cloud evaporated, and seemingly instantly the ride smoothed out. With more than half the mass of Earth’s blanket of air behind them, Constitution’s engines once again spun up to full power.
“Houston, Constitution,” John Young called over the radio, ”Go at throttle up!!” The stack had cleared the test of Max-Q, the pressure was falling, and all systems remained nominal. Downrange, there was only the blue of the sky above, and the blue of the sea below. The stack cut through it like a knife, a delta-winged dart breaking trail for a tail of flame which now spread in the less dense air to several times the ship’s wingspan. Space lay ahead.
The official certification of the Space Lifter as “operational” came as a relief to the thousands of people both at NASA and at innumerable contractors who had poured almost a decade in turning the concept of a reusable space launch system from a dream of s-f magazine covers into a real, working system. The Space Lifter and the Space Shuttle were the first of a new breed of launchers designed to go to space not once but dozens of times, and to open up a new era of space development. The three operational RS-IC boosters had already demonstrated their reusability, with
Independence and
Constitution both having completed 8 orbital launch missions by the time STS-8 had returned from orbit.
Endeavour’s came, of course, after that debut mission, with the orbiter returning to space next eight months later. The dreams of Von Braun and others of orbital ferries had been realized in some form. However, while the pressure of development abated, the pressure of the program’s own inertia and of the expectations of the newly “operational” system built up, and only raised the stakes. The moment of maximum program pressure still lay ahead. For STS to be a success, Shuttle and Lifter would have to prove that they could indeed not just fly repeatedly, but also cheaply, rapidly, and safely. While doing so they would be able to satisfy the needs of the many customers whose buy-in NASA had secured with promises about the Space Transportation System’s capabilities.
These promises had yielded an impressive backlog of missions for the Space Lifter. The first half of 1980 had already seen two completely commercially-driven missions using the Space Lifter’s Multiple Launch Adaptor to place payloads on their way to geostationary orbit. Following STS-8, there were two more such flights on the year’s manifest. As with the earlier missions, the payloads were undersized for the LIfter, even with multiple launch capacity, totalling less than a third of the vehicle’s geostationary transfer payload. Satellite buyers were still waiting to see if Lifter’s promised cost reductions and flight rate would be sustainable before purchasing any satellite which couldn’t be flown on other systems. Until then, Lifter’s true commercial potential would go unrealized. Still, every successful launch seemed to encourage two new bookings, and as Lifter racked up a successful record, customers we more willing to consider busses which were--technically--launchable on other launchers, even if those launchers were large enough and costly enough to be prohibitive as anything other than a fallback. Hughes had been doing booming business in their HS-376 bus, which had a mass of just over a ton at separation, and which had been the first commercial payload on the Space Lifter. By 1982, Hughes was working on a backlog of more than a dozen orders for the platform, and sold eight more in that year alone. They also took a risk, working with Intelsat to develop a new satellite bus which would mass more than four metric tons at separation. It was, at least nominally, capable of being lofted by alternate vehicles like Titan or evolved Ariane derivatives, but the main launch plan would be Space Lifter--which could accommodate two such monster satellites comfortably in the same flight. The satellite, and others like it offered by competing firms, were larger and more capable than any planned for geostationary use before--indeed, they could accommodate more mass in communications equipment and antenna than the entire fueled weight of some previous-generation commercial busses. Though Intelsat and Hughes had been the first to fully commit to such capable busses, they wouldn’t be the last, and some designers had tossed around the potential for what could be done with a
full Lifter launch. Such build orders and discussions ultimately lead these builders and customers to turn up the pressure on NASA to deliver reliable launches on tempo, and Space Lifter would have to push on and deliver.
While the Space Lifter made regular launches of commercial and governmental payloads, the Space Shuttle orbiter was still in its test phase throughout 1981 and 1982. For all the that entire Space Transportation System had been declared officially “operational” after its first flight of Lifter and Glider together on STS-8, Shuttle itself had many more capabilities to shake down. The first flight had been focused on proving the basic functionality of the vehicle: reaching orbit, opening the payload bay doors, deploying the Canadarm robotic arm, and communicating with the ground via TDRS. However, the next Shuttle flight would take more than 6 months to occur, as engineers and technicians crawled all over and through
Endeavour, reviewing the effects of the flight on her structures and systems. The information was filtered back to the construction bays at Palmdale, where two more Orbiters were taking shape. In the meantime,
Endeavour took flight once more atop the booster
Intrepid for the STS-12 mission.
The glider’s second mission was, in some ways, an extension of the first.readied again for her second flight. While STS-8 had stuck steadfast to the most basic capabilities of the orbiter, staying up for only a day, STS-12 was a more comprehensive test of the orbiter’s capabilities. The crew was still limited to the commander and co-pilot, but the mission duration was extended to a five-day flight--less than the shuttle’s maximum endurance even with a full crew, but offering much more time for the crew to test the ship’s systems. While Fred Haise and Richard Truly had tested the basic motion of the Canadarm on STS-8, and used it to conduct basic inspection of the ship’s thermal protection tiles, STS-12 saw Ken Mattingly execute several more detailed tests of the arm’s manipulator abilities in space, unlatching and repositioning a test payload within the shuttle’s cargo bay. That test payload wasn’t alone; while STS-8 had flown empty, the bay on STS-12 carried several scientific and engineering payloads. Most valuable were a bank of earth-sensing instrument pallets presented with a perfect chance to do their task by opening the shuttle’s cargo bay doors and rolling the bay to face the Earth, then being returned to the surface. Even her descent offered a chance to push the edges of the envelope STS-8 had carefully shied away from: while STS-8 had made an automated descent carefully plotted down the middle of every band engineers could design her for in the tempest of entry, Mattingly took a manual hand on the stick in STS-12’s descent, guiding Endeavour through more aggressive maneuvers as she returned to Earth. These twists and turns tested the spacecraft’s ability to maneuver at hypersonic speeds in the rarified upper atmosphere and exposing special sensor pods on the glider’s tails to new engineering regimes.
Endeavour marked her return to Earth with a bang, leaving a cone of her lifting body shape’s characteristic sonic booms as she glided to a landing at the Cape, with Mattingly putting her down within three inches of the runway centerline. Though other reusable had flown to the edge of space,
Endeavour now proved she was the first truly reusable orbital spacecraft.
These patterns of expanding envelopes followed on the next Shuttle mission, this time on STS-15 in July 1981.
Endeavour rode to orbit on yet a third booster, the debut launch of the brand-new
Liberty. The flight once again pushed the duration, extending to a full week in space, and for the first time active experiments were carried inside the Shuttle’s cabin for the crew to work on during the flight. However, that crew was still limited to two, and their time was constrained both by the pre-planned tests of the Shuttle’s orbital maneuvering abilities, as well as by a serious failure in the Shuttle’s hygiene facilities, and particularly its orbital toilet. Though the issues with the system’s flush apparatus lead to several colorful exchanges with engineers on the ground, the crew dealt with the other minor issues on the flight, such as overheating in one of the spacecraft’s auxiliary power units, and made a nominal return. Due to the vagaries of the Space Transportation System’s schedule, the final test mission came four months later. Though
Endeavour was ready in three, a delayed communications satellite mission prevented the originally scheduled launch date from being met. This mission saw the Shuttle finish off a round of the Lifter fleet, flying on the newly refurbished
Independence in early November. The STS-18 mission largely duplicated STS-15, matching it in duration and scope. However, for the first time, the orbiter deployed a payload--a small classified Department of Defense satellite--from the payload bay with the aid of the Canadarm. On her return,
Endeavour conducted her most sweeping in-atmospheric maneuvers yet, continuing to prove that the orbiter had the cross-range capabilities required to return to land following a one-orbit mission to polar orbit from Vandenberg--a capability of interest not only to the DoD, but for a single-orbit “Once Around” abort of any mission to that orbit. Upon
Endeavour’s latest return to Earth, President Reagan sought his own chance to leave a mark on the space shuttle program. While Carter had commemorated STS-8 by marking the operational status of the Space Lifter, Reagan now met Endeavour at Edwards Air Force Base in the President’s home state of California, and officially announced that the Space
Shuttle was now operational--and with it the
entire Space Transportation System.
Following its proving-out missions, the Space Shuttle faced the challenge of operational missions. While the glider’s development had been delayed, missions hoping to make use of the orbiter had been building up a manifest, and with
Endeavour and her (yet unfinished) sisters commissioned as operational, the pressure to start accomplishing these task only increased. Over her next three missions,
Endeavour put her capabilities to the test. Though the airlock had been cycled in space on test missions, STS-21 in February 1982 brought the first EVA from the Space Shuttle, enabled largely by the first four-person crew, featuring not just pilots by two mission specialists. The task they faced on this flight was another milestone: the deployment of the Long Duration Exposed Facility (LDEF) from the cargo bay. The LDEF was a pallet of experiments on biology, physics, and materials. Its launch on
Endeavour was planned to be followed by return on another Shuttle mission in a year, with subsequent reflight of slightly altered platforms to follow. STS-21 was not just the largest crew ever launched by the United States, but the most diverse to that date. Copilot Guion Bluford became the first African American to fly in space (though not the first black man, a milestone claimed by the Soviet Union with the launch of Cuban cosmonaut Arnaldo Mendez in 1980), while Judith Resnick, as the mission specialist in charge of operating the Canadarm and deploying the LDEF, became the first American woman in space.
It is worth mentioning, in the context of the Cold War propaganda struggle, that the Soviet Union answered Resnick’s flight by launching the woman cosmonaut Svetlana Savitskaya on the Salyut 7 mission just weeks later. During her 3-week flight, Savitskaya became the first woman to perform an Extra-Vehicular Activity, and the second Soviet woman in space. Unfortunately, she would also be the last Soviet woman in space, as the Soviet cosmonaut corps was generally hostile to women cosmonauts. As Professor Anatoliy Grigoryev remarked after 1991, when he was named Director of the Institute of Medical and Biological Problems, “women are fragile and delicate creatures; that is why men should lead the way to distant planets and carry women there in their strong hands.”
Other Shuttle payloads required less handling: on STS-24 in June,
Endeavour’s crew began their mission with the deployment of a small geostationary orbit satellite, attached to a compact solid rocket motor to perform apogee raise to a traditional GTO after deployment. This package, intended for satellites massing 600 kg or less, was an option developed by NASA for satellites which were too small to effectively utilize even a slot on the STS Multiple Launch Adaptor. While such payloads couldn’t justify even half the cost of an STS launch, these “fire-and-forget” GTO deployments from the Space Shuttle’s bay were subsidized by the NASA missions they flew with, and thus were available at lower cost--though with less opportunity. It was another example of the pressure NASA was under to develop ways to maximize revenue from the STS, both Lifter and Shuttle, and offer as much capability to American and international customers as possible.
The STS-24 primary mission objective was a demonstration of an even more important capability: the orbital repair of a damaged satellite to return it to operational service. The Solar Maximum Mission was a NASA scientific spacecraft which had been launched two years prior to study the sun and its cycles. However, just nine months into its mission, the failure of half the fuses in its attitude control system limited the spacecraft to operating just three of its seven primary instruments. However, the spacecraft had been designed with a grapple fixture for the Space Shuttle robotic arm, and STS-24 was assigned the task of directly intervening to restore the satellite to full function. The task was not simple: undocumented modifications in production not reflected in the plans meant that the shuttle could not use the original planned maneuvers to stabilize the spinning spacecraft. In the end, the only option was for an astronaut to grab onto the spacecraft’s delicate solar array and apply torque with his MMU to stabilize the spacecraft-risking tearing the array off entirely. The approach worked, though not without a failed attempt which almost doomed the spacecraft entirely before the ground and the astronauts could prepare for a second attempt. Once the satellite was stabilized and grappled, the mission proceeded more to plan. The entire suspect attitude control system was removed and replaced and upgrades were made to the spacecraft’s suite of scientific equipment, replacing one instrument and modifying another. By the end of the mission, not only had the spacecraft’s function been restored, but it was more capable than it had been at launch two years earlier. This example, carried out on a spacecraft only obliquely intended for in-space servicing, was a powerful demonstration for future spacecraft which might depend on such tending--and of the considerations for rendezvous, grapple, and orbital maintenance which must be accounted for. It was watched with interest not only by major programs within NASA which were built around this capacity, like the Large Space Telescope and Spacelab, but also by more classified projects under the aegis of the USAF.
While the Space Shuttle was proving out its basic capabilities, the Space Lifter was facing the pressure of demonstrating its full promised capacities as launch rate ramped up to meet the demands--and the optimistic projects NASA had made to sell the system’s development. In 1977, the Lifter’s booster had debuted with a single suborbital test. The next year had seen three more suborbital test flights, plus a qualification flight of an active upper stage and mass simulator. Topping this, 1979 had seen four orbital flights, then 1980 had seen six. Faced with increasing demand for launches from commercial satellite operators, the Department of Defense, and the addition of the Space Shuttle, subsequent years called for every year to exceed the previous year by at least two launches a year. A launch rate of one per month every month was called for no later than 1983. Considering the usual issues with operating any new program, not to mention the complexities of scheduling rockets around customer demand, contractors and suppliers, weather, and NASA’s own internal schedule priorities, this was ambitious, but the efforts to avoid slipping schedules were complicated by scheduled SLIP: the Spacecraft Lifespan Investigation Program.
The Space Lifter’s RS-IC booster was designed for a long, effectively unlimited lifespan per vehicle, with rapid and cost-effective turnaround between flights. The hope was that a mature booster program would be capable of turning a booster around in as little as a week, hopefully with little more inspection or overhaul than a high performance military aircraft. NASA knew that this was an optimistic goal, and had no experience with operating a reusable suborbital spacecraft of this scale for so many flights. Ground tests had validated thermal protection systems, engines, and the airframe and tanks for dozens or more cycles. However, it remained to be seen how closely the Lifter booster would align with those test results in service. Inspections to determine the alignment would require sacrifices which would make NASA’s goal of rapid reflight challenging if not impossible: crawling over every inch of vehicle, inside and out, on every flight. Drawing on the example of continuous aircraft maintenance programs for commercial and military aviation, SLIP would consist of varying levels of checks, with increasing levels of rigor, conducted at scheduled intervals. Some checks and maintenance would be carried out every flight during routine turnaround, such as basic computer checks, visual inspection of external surfaces, and the functionality and condition of critical primary and secondary systems. Others were scheduled in alternating combinations every second flight or on similar intermittent schedules, such as borescoping the F-1B turbopumps. However, at scheduled milestones, each airframe in turn would face a SLIP inspection of similar scope to an aircraft “D” check: a near complete inspection of every component in every detail, including substantial removal and replacement of components.
Though much of these SLIP checks had been part of the experimental test program prior to the first orbital flight, the first milestone for “operational” SLIP inspection was six flights into the boosters’ lives. Though some of these checks had been conducted after every early flight, the first major check was scheduled to follow the sixth mission for each booster. Until these heavy inspections and overhauls were completed, the boosters wouldn’t return to the flight line.
Independance was the first to hit her maintenance interval, being moved off the active list following her sixth flight to launch STS-6 in April 1980.
Constitution followed in turn after STS-8. During this overhaul, the boosters departed from the Cape, ferrying back to their construction sites for inspection more intense than could be managed in the booster processing facilities at Kennedy. Many of the same engineers and technicians who had originally built them now crawled all over their charges for months on end. The boosters’ main engines and its hydrogen peroxide thrusters were safed and removed, enabling inspection of the entire systems. The ten airbreathing engines were removed as well, and their hydrogen peroxide start turbines were inspected as well for erosion or damage. Portion of the boosters’ propellant feed lines were removed and replaced, with the old ones sent to but cut up for metallurgical testing. The entire cockpit ejection pod was removed from each booster for the first time. Pyros and solid ejection motors were removed, replaced, and the old ones tested. Sections of the boosters’ titanium and aluminum heat shield were removed for similar tests, and the entire boosters’ protective coatings were stripped to enable inspection of the skin itself inside and out. Every possible wire in the vehicle was tested at both ends to ensure proper signals, and sensors were removed and tested. While the inspections went on, any defects were catalogued and repaired, building a picture for how the two boosters had aged in service.
Overall, the issues found by inspections of the Lifters, at least, were minor and in line with what had been expected based on the ground tests and turnaround checks between missions. While the repairs were made, a few minor improvements were incorporated based on the experiences of the initial years of flights and development in the meantime. The most important were minor upgrades to the booster’s computer systems, but the most visible was to the boosters’ appearance.
Independence and
Constitution had originally been painted a clean white, intended to enable easier evaluation of potential damage to the coating or the all-important aluminum and titanium skin behind it. However, in service, the benefits of this visual inspection had been found to be biased by pure surface discoloration from the high temperatures encountered during booster entry and discoloration from previous flights if the booster wasn’t laboriously washed between missions. New non-destructive evaluation methods were also introduced to supplement and even replace the pure visual evaluation. Thus, when
Intrepid had received her Air Force paint job, she had been colored a light gray on her top surfaces, and black on the belly, which had proved after STS-7 to show much less visual change between flights. While
Intrepid still needed to be cleaned between flights to remove the worst of the charring, this could be done with essentially an oversize car wash, and removing non critical but heavily visible char no longer required as much labor. Thus, when
Independence and
Constitution received a clean bill of health to return to the flight line for another dozen missions each, they would wear the same paint job.
While the pressure was on SLIP to prove that NASA had achieved its goal of a heavily reusable booster, the absence of two of the three operational RS-ICs from the Cape left the pressure of the entire launch program to be borne by
Intrepid alone. The program’s ability to meet its high-pressure schedule goals through the end of 1980 and early 1981 would depend largely on their ability to prepare a single booster for reflight. As soon as
Intrepid returned from launching a pair of commercial communications satellite on STS-9 in September, crews set to work to ready her for a Department of Defense payload to be launched on a dog-leg polar trajectory in November. With this classified payload (in fact, the final KH-11 optical spy satellites) deposited into LEO,
Intrepid was turned around for a January launch of another pair of comsats on STS-11, before finally launching the Space Shuttle
Endeavour’s second flight to orbit on STS-12 in March. While the two-month durations between missions weren’t a severe trial of the turnaround that Lifter could manage, the effects meant that delays in preparing any one missions cascaded directly onto the next--there was no second booster stacking in the VAB while
Intrepid waited for launch windows to open up in wind and weather. It made the one-month turnaround achieved between STS-12 and STS-13 in April all the more impressive, especially given the debut of the new Centaur-G stage used on the launch of the DoD Chalet satellite to geostationary orbit as preparation for future NASA use of the stage for interplanetary flights.
The Boosters were not the only vehicles caught up in SLIP schedules. Following STS-24 and her sixth launch,
Endeavour was removed from service for her own SLIP-I inspection, and a similar in-depth inspection was conducted. In addition to her usual post-flight OMS inspection, her abort engine system was removed and the modified LR-91 engines inspected. During her absence, the second NASA Orbiter, OV-103
Discovery, replaced her for further flights, with her maiden flight on STS-27 in October.
Between SLIP inspections and
Intrepid’s marathon run bearing the entire launch manifest for STS, the Space Lifter booster was proving its value. Though the cost per flight of a Space Lifter mission was above $40 million instead of the $18.5 million originally promised in 1971, this was actually to slightly lower than the original estimates when accounting for inflation. However, there was still pressure to further reduce costs, and much of this focus turned to the major expendable portion of the system: the S-IVC stage. More than half the cost of each flight was in the structures of the S-IVC, disposable interstage, and launch fairings, with another substantial portion being the J-2S-2 engine, while the production rate of S-IVC stages was projected to potentially be the limiting factor in STS operations if a fleet of four boosters (including booster RS-IC-604
Liberty which was completing testing prior to delivery) were each capable of launching once a month. While reducing booster turnaround costs could help in boosting flight rate, the production of upper stages was the main target for pressure for program cost reduction and production throughput increases. McDonnell was challenged on whether the rate of production and cost of each stage could be increased by further automation, while process engineers worked through every step to minimize delays, increase utilization of fixed-overhead equipment, and reduce manual labor.
Additional benefits came as McDonnell would no longer acceptance fire each stage as a unit. Instead, Rocketdyne’s acceptance firings of each engine would be used to qualify a lot, which would be delivered for assembly. After assembly, a wet dress rehearsal of the stage would test and qualify the stage’s structures and plumbing, but the SACTO test site would be mothballed, as there were no further plans for static-fires of complete S-IVC stages. The results helped stem the growth of operational costs, but involved accepting a certain degree more risk. Even as engineers fought to achieve further cost reductions, they were developing confidence in their product as production fell into a rhythm. The S-IV had already passed the flight history of the 200 series and 500 series of the S-IVB, not to mention the original S-IV, and was on track to pass the combined production of the S-IVB 200 and 500 series by the end of 1982. As the peak pressure bore down on the STS program to deliver flights, reduce costs, and launch critical payloads, the work of engineers to ensure the ongoing supply of S-IVC stages was little more than a footnote.
While the launch portions of the Space Transportation System was focusing on bearing up under the rising pressure of operational missions, NASA attention was focused on the high-profile internal programs which Space Lifter and Space Shuttle would enable. The largest for NASA’s human spaceflight program was the Spacelab man-tended platform. The Spacelab program can trace its origins to the cooperation agreements between the European Space Research Organization (ESRO) and NASA, beginning in the late 1960s and escalating under the Nixon Administration. In 1970, NASA Administrator Tom Paine briefed ESRO managers on his expansive vision for NASA’s post-Apollo goals--a fleet of space stations in orbits from LEO to the Moon, a swarm of space tugs moving payloads to and fro between them, a fully-reusable Space Shuttle to launch all of it from the ground, and, as the cherry on the stacked cake, crewed voyages to Mars and even beyond. Of most interest to ESRO, which had achieved some success building scientific satellites, were the space stations. The industrial applications of high-molecular-mass crystal growth and microgravity manufacturing techniques offered the chance for medium-term return-on-investment, a stimulus for the European manufacturing and pharmaceutical sectors (particularly that in West Germany). As the US government made it clear that the proposed Space Tugs could not be outsourced to Europe (due primarily to concerns about sharing cryogenic rocket technology), ESRO concentrated its attention on European participation in the Space Station projects.
Though both ESRO and NASA were in agreement that they wanted to work on a Space Station in the near future, the two agencies brought to the table very different assumptions about the actual purpose of the station. Indeed, even within NASA, there was, until 1973, no clear consensus on just what the station would be for. Marshall Space Flight Center, still under the spiritual (if not actual) leadership of Wernher von Braun and his German team, envisioned an orbital shipyard, propellant depot, and manufacturing facility where ships and satellites were assembled and refueled for journeys further out into space. Such facilities would be necessary for the realization of the voyages to Mars that von Braun had envisioned decades before--only in the wide expanses of space could the vast landing craft and spinning, nuclear-powered interplanetary ships be assembled. Johnson Space Center, for its part, shared the belief that the Space Station’s purpose was to support longer-term human exploration of space, but envisioned the Space Station as essentially a test article for an interplanetary ship--a proving ground for advanced life-support systems, with the ultimate goal of complete life-support system closure. For their parts, the scientists from Goddard, Ames, and Lewis Research Centers all had different focuses within the broad umbrella of “space science,” and while they generally envisioned smaller vehicles, they differed on the subject of where a space station should go, whether it should be permanently manned (or manned at all, as a persistent minority at the Jet Propulsion Laboratory kept asking), and how much human intervention in the experiments was actually required.
It was somewhat fortunate for ESRO, then, that the Nixon Administration was considerably less ambitious with regard to spaceflight than Administrator Paine had hoped. By 1971, the administration had made clear that NASA’s budget would not be nearly large enough to afford the interplanetary empire Paine had described to the Europeans. Instead, the agency would have to pick the element of the system it found most useful--the Space Transportation System, the combination of Lifter, Orbiter, and disposable second stage.
The cancellation of plans for the permanent Space Station, however, did not end all discussion of human-operated experimental platforms. The Orbiter proposed for the Space Shuttle system was to have an on-orbit lifetime at least several days long and enough payload capacity to carry out scientific experiments on-orbit. Program managers proposed to add to this capability by installing a reusable laboratory module, which could be carried in the payload bay. This “Sortie Can” attracted some interest on both sides of the Atlantic--Grumman Aerospace went as far as recycling some of its Lunar Module Laboratory (LM Lab) concepts, initially developed for the Apollo Applications Program, into proposals for a Sortie Can. The concept was particularly popular at Ames Research Center, whose experience with the flying Galileo laboratory (carried inside a modified Convair 990) illustrated the flexibility and utility of a frequently-flying multi-instrument platform. However, as the limitations of the Orbiter’s consumables, electricity, and payload capacity became clear, attention shifted from the Sortie Can to a proposal that originated in Europe, initially termed the Man-Tended Free Flyer.
In its scale, Man-Tended Free Flyer was much closer to Skylab than the Lunar Module Laboratory. The new proposal envisioned a 30-tonne pressurized Laboratory Module attached to a 10-tonne Service Module that could provide 25 kilowatts of electricity. The Laboratory Module would host experiment racks for a host of different microgravity science experiments, and external attachment points for materials science investigations in the hard-vacuum, high-radiation environment of outer space. The Laboratory Module’s life support system would be developed by ESA, with some American input. As MTFF missions would be limited initially by the orbital lifetime of the Orbiter, the life support system was optimized to support a crew for up to one month at a time, with most of the actual consumables for the stay (water, oxygen, food) carried by the Orbiter. In essence, MTFF would serve as a cabin in orbit, with a stay time dictated by how much food, water, and power the Orbiter could carry up to it. In order to overcome the limits of the Orbiter’s planned 7-day lifespan, the Service Module would be capable of providing electrical power to the Orbiter, extending the small craft’s lifetime from a week to a month or more.
The Man-Tended Free Flyer was attractive to scientists in Europe and in some of the American space centers, but not all. By excising the closed life-support system, the MTFF became incompatible with Johnson Space Center’s vision for space stations, and its utility for on-orbit construction was also limited (but not zero--small-scale experiments with assembly and manufacturing in microgravity and hard vacuum could be performed). The vehicle could have been placed in a polar orbit, but this was not ideal, as it would limit the amount of payload that an Orbiter could take up to it. Orbits from 23 to 52 degrees in inclination were discussed, though only the upper ranges satisfied earth science specialists. Physicists and astronomers in both Europe and America were the most hostile to MTFF, considering it a distraction and diversion of funding from unmanned spacecraft, including NASA’s then in-development Space Telescope. Ultimately, however, the program benefitted from the fact that it was essentially a European enterprise--a program run by Europeans did not need to satisfy every lobby in America. Though NASA had taken a new look at MTFF in 1972 (as part of a directive from the President to tie America’s allies more closely into its achievements in space), the program could only be brought to fruition if it were managed primarily from Europe.
What remained in 1973, then, was the question of how to actually fund and authorize the MTFF. West Germany and its supporting countries in ESRO (Belgium, the Netherlands, Luxembourg, and Italy) remained very interested in developing MTFF, as visions of wonder-drugs and miracle-metals danced in front of their eyes. France and the United Kingdom, however, had differing priorities. After the Europa debacle, France wanted to recommit Europe to a new launch vehicle program, to ensure independent access to space communications for Europe and independence from the American Intelsat monopoly. Britain, for its part, was most interested in a maritime communications network to support its still-significant economic ties to its former colonies. The compromise between the three blocs, signed in 1973, to take effect in 1975, secured each of these programs, assuring each European contributor that its support would be rewarded by support for its own preferred program. ESRO and ELDO were to be merged into a new European Space Agency, which would develop Ariane, MTFF, and the new maritime communications network (though this last would eventually be spun off into INMARSAT).
ESRO awarded the prime contract for the development of the MTFF, which had been dubbed Spacelab by the Americans and those Europeans who worked most closely with them, to the West German consortium ERNO, a joint venture of Weser Flugzeugbau and Focke-Wulf. ERNO would be tasked with building the Laboratory Module, Exposure Facilities, and Service Module for Spacelab, though they would receive advice and support from NASA’s Marshall Space Flight Center on the Service Module (drawing on that center’s experience developing Skylab) and Ames Research Center on the Laboratory module (drawing on that center’s experience with the Galileo flying laboratory). After the spacecraft was completed and launched, it would be controlled primarily from the European Space Operations Center in Darmstadt, Germany, though the American experimental pallets would be controlled from Ames (in coordination with Darmstadt), and visiting Space Shuttles would, of course, be under the control of Johnson Space Center.
The Space Transportation System was always intended to become NASA’s primary launch vehicle for all payloads, including those managed by the Jet Propulsion Laboratory and Goddard Space Flight Center for planetary science, astronomy, and heliophysics. For such missions, NASA turned to the venerable Centaur upper stage, which had been the agency’s first vehicle to burn cryogenic hydrogen and which remained the upper stage of choice for scientific and unmanned payloads. Managed by Lewis Research Center and manufactured by General Dynamics, the Centaur had proven its worth as an upper stage for the Atlas rocket, boosting that vehicle’s geostationary transfer orbit payload and turning a first-generation ICBM into a reliable and high-performance launcher for commercial and government payloads. As interplanetary payloads increased in mass, it had also proven very adaptable, moving from the Atlas launcher to a Titan III. Centaur had launched the Pioneer spacecraft to the outer solar system, the Surveyor spacecraft to the Moon, and the Mariner spacecraft to Mercury, Venus, and Mars--though there was some protest from the USAF in favor of a solid-propellant Inertial Upper Stage (so favored for its perceived adaptability to different payload sizes and the reliability of solid rockets) for GTO and interplanetary payloads, the performance of cryogenic hydrogen and the fact that Centaur was already available meant that the debate was brief and Lewis Research Center began work in 1975 on a scaled-up Centaur-G upper stage to fly on the Space Lifter.
The primary difference between Centaur-G and the earlier Centaurs that had flown on Atlas and Titan IIIE was its diameter. In order to take advantage of the greater diameter of the Space Lifter’s upper stage, Centaur-G’s hydrogen tank diameter was increased 60%, from the original 10 feet to 16 feet, while the length fell from 31.5 feet to 20 feet. Though Lewis Research Center and GD both also proposed even larger Super Centaurs with lengths restored to the original 31.5 feet and even beyond, for super-sized outer solar system payloads, the stubby Centaur-G was deemed by NASA headquarters and the USAF to be sufficient for the near-term needs of both organizations.
Centaur-G’s first test flight came on April 6, 1981. The payload was managed by the Department of Defense, and remains mostly classified, but a general consensus has emerged that it boosted an electronic intelligence payload to Geostationary Orbit, after which the Centaur-G demonstrated other new features that had been integrated into the design: an increase in multilayer insulation that reduced the propellant boiloff rate from 2% to under 1% of loaded propellant per day, and an optional solar array that extended the stage’s useful life from mere hours to several days. The Lifter-Centaur stack was drastically overpowered for this particular payload, so the Centaur-G retained a significant load of both liquid hydrogen and liquid oxygen after injecting the payload. The earlier Centaur had demonstrated the ability to restart its engines up to seven times, with a coast period over 5 hours long between burns. The upgraded Centaur-G duplicated that coast time, restarting at 300 kilometers above Earth’s surface after circularizing the payload’s orbit and then dropping itself back down toward Earth. The stage and its propellant load were monitored in Low Earth Orbit for another 72 hours before the engines were lit one last time to fully de-orbit the Centaur. Though not strictly necessary for the success of the primary mission, this test of the Centaur-G’s long lifetime and multiple-restart capability was a helpful demonstrator for NASA’s long-term plans to introduce a fully-reusable space tug and to use Centaur-G as the basis for a Service Module to increase the utility of the Orbiter on more complex LEO missions.
The major successes of the transition of the Space Transportation System from a development and test program to an operational launcher and orbital spacecraft came in spite of some serious shakeups on the ground in the team responsible for the manufacture and preparations of the vehicles. The Space Transportation System involved three prime contractors, three major government agencies (NASA, the FAA, and the USAF), and a host of subcontractors, launching payloads that varied in everything from size to security classification to launch window tolerance. The Reagan Administration analyzed a number of different approaches for consolidating management of the program, including keeping the program under NASA management (an option disliked by the USAF, which wanted to manage its own Lifter and Shuttle fleet), creating a new government agency or corporation (disliked by the Administration, which had campaigned on the promise of curbing the size and scope of government and controlling the proliferation of agencies), and creating a new Government or Private corporation. Ultimately, the option chosen was to have Boeing and McDonnell-Douglas create a new joint venture--the Space Transportation Corporation--that would consolidate all Space Lifter operations under one roof, and through which all Lifter launches would be contracted. The USAF and NASA would buy launches on the Lifter in essentially the same manner that a government office would ship packages through a cargo airline like Federal Express, though, in the case of the former agency, with considerably more oversight on classified payloads. Orbiter operations, as they had less of a market case and more implications for international diplomacy, would remain under the administration of NASA’s Manned Spacecraft Center and, in later years, the United States Air Force. The STC would have, however, have the option to buy excess capability on Space Shuttle missions back from NASA on a prorated basis for deployments of small “ride-along” comsat deployments from the glider’s payload bay, such as that carried out on STS-15 or STS-24.
Among other consequences of the creation of the Space Transportation Corporation was the gradual divorce of Marshall Space Flight Center from the day-to-day operation of the Lifter fleet. Though the center remained firmly involved in plans to utilize the Lifter’s capability for NASA’s planned space station, and worked closely with Boeing and McDonnell to iteratively improve the Lifter design in smaller ways, the concentration of STC assets at Michoud Assembly Facility, the West Coast assembly plants owned by the prime contractors, and the launch pads at Cape Canaveral and Vandenberg Air Force Base increasingly meant that Kennedy Space Center took the lead in actual NASA use of the Lifter, handling payload integration and the specialized facilities that NASA had built up for the Apollo Program and converted for use with the Space Transportation System. With the cancellation of the “Shuttle II” design studies and the delivery of the Spacelab service module for final assembly at the Cape, MSFC saw a wind-down of the development work for which it had been founded, and the center would become a major source of lobbying for a plan for a new, major NASA program as the 1980s progressed.
Though the transition from development to operations did not equally enrich all branches of NASA, and introduced a significant degree of confusion in the first weeks of STC’s existence as the corporate cultures of Boeing and McDonnell-Douglas were forced together, the Space Transportation System seemed well on its way to becoming a successful launch vehicle by 1982. STC won many new communications satellite contracts, and its growing record of reliability inspired mission planners at NASA, commsat manufacturers like Hughes, and the secretive National Reconnaissance Office to begin planning to utilize the full range of the system’s capabilities. Several important institutional payloads planned to use the system were in the final stages of preparation, most critically the European Pressurized Module and the Marshall-built Service Module for Spacelab which arrive at the Cape for final assembly. The boosters
Independence and then
Constitution returned from their SLIP inspections cleared for another dozen missions each, and the fourth and final booster,
Liberty made its debut flight. As the Lifter closed out 1981 with its 8th launch of that year (and 19th overall orbital launch), it seemed that the system’s future was bright and clear. The pressure began to come off even as the launch rate was only set to accelerate.
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