The worldwide euphoria over mankind's greatest voyage of exploration did not rescue the NASA budget. At its moment of greatest triumph, the space program was being drastically cut back from the $5 billion budgets that had characterized the mid-1960s. Part of the reduction was expected; the peak of Apollo production line expenses was past. But the depth of the cut stemmed from emotional changes in the political climate, mostly centering on the unpopular Vietnam war--its sapping expenses in lives and money, the debilitating protests at home. As Congress read the public pulse, the cosmos could wait; the Soviet threat had for the moment been put to rest; the new political reality lay in domestic problems. NASA's fiscal 1970 budget was reduced to $3.7 billion. Something had to give. The basic Apollo mission was continued, but the last three flights had to be deleted. Space science projections were hit hard. The ambitious $2 billion Voyager program for planetary exploration dwindled into oblivion; it would later resurface as the much more modest Viking. The new Electronics Research Center in Cambridge, Massachusetts, under construction since 1964, was transferred to the Department of Transportation intact--a $40 million facility taking with it 399 of 745 skilled employees.
Space Probes and Earth Satellites
But the bought and paid for projects continued to earn dividends. An Orbiting Astronomical Observatory (OAO-2) was launched 7 December 1968. It was the heaviest and most complex automated spacecraft yet in the space science program. It took the first ultraviolet photographs of the stars. The results were portentous: first hard evidence of the existence of "black holes" in space. Mariner 6 and Mariner 7, launched in early 1969, journeyed to Mars, flew past as close as 1900 miles, took 198 high-quality TV photos of the planet, 2000 ultraviolet spectra, and 400 infrared spectra of the atmosphere and surface.
Other programs continued with prepaid momentum. The fifth and sixth Orbiting Solar Observatories (OSO) were launched in 1969, as was the sixth Orbiting Geophysical Observatory. In 1970 Uhuru was launched and scanned 95 percent of the celestial sphere for sources of x-rays. It discovered three new pulsars in addition to the one previously identified. In 1971 Mariner 9 was launched; on 10 November, the first American spacecraft went into orbit around another planet. The early months in orbit were discouraging; a gigantic dust storm covered most of the martian surface for two months. But the dust gradually cleared; photographs in 1972 showed startling detail. Mapping 85 percent of the martian surface, Mariner 9 photographs depicted higher mountains and deeper valleys than any on Earth. The rocky martian moons, Deimos and Phobos, were also photographed. OSO-7, launched on 29 September 1971, was the first satellite to catch on film the beginning of a solar flare and the consequent streamers of hot gases that extended out 10.6 million kilometers; it would also discover "polar ice caps" on the sun (dark areas thought to be several million degrees cooler than the normal surface temperatures). With the confirmation of black holes, the enigmatic collapsed star remnants so dense in mass and gravity that even light cannot escape, and the previous discoveries of quasars and pulsars, these findings added up to the most exciting decade in modern astronomy.
Planetary exploration opened further vistas of other worlds. Pioneer 10, launched 2 March 1972, left the vicinity of Earth at the highest velocity ever achieved by a spacecraft (32,000 MPH) and took off on an epic voyage to the huge, misty planet Jupiter. Giant of the solar system, swathed with clouds, encircled by a cluster of moons, Jupiter was an inescapable target if one hoped to understand the composition of the solar system. Out from the Sun, out from Earth, Pioneer 10 ventured for a year and a half, through the unexplored asteroid belt and far beyond. After a 992 million kilometer journey, on 3 December 1973 the tiny spacecraft flew past Jupiter. It survived the fierce magnetic field and sent back photographs of the huge planet and several of its moons, measured temperatures and radiation and the magnetic field. Steadily sailing past Jupiter and away from the Sun, in 1987 Pioneer 10 would cross the orbit of Pluto, becoming the first man-made object to travel out of our solar system and into the limitless reaches of interstellar space.
Pioneer 10's partner, Pioneer 11, took off on 5 April 1973 to follow the same outward path. On 3 December 1974 it passed Jupiter at the perilously close distance of 26,000 miles--as opposed to 80,000 for Pioneer 10--and returned data. The composite picture from the reports of the two spacecraft depicted an enormous ball of hydrogen, with no fixed surface, emitting much more radiation than it received from the Sun, shrouded with a turbulent atmosphere in which massive storms such as the Great Red Spot (25,000 miles in length) had raged for at least the 400 years since Galileo first trained a telescope at Jupiter. Pioneer 11 swung around the planet and, taking advantage of Jupiter's gravitational field, accelerated outward at 66,000 MPH toward the distant planet Saturn, where in 1979 it would observe at close range this lightest of the planets (it could float on water), its mysterious rings, and its 3000 mile diameter moon Titan.
Going in the other direction, Mariner 10 left Earth on 3 November 1973, headed inward toward the Sun. In February 1974 it passed Venus, gathering information that confirmed the inhospitable character of that planet. Then using Venus's gravitational force as propulsion, it charged on toward the innermost planet, Mercury. On 29 March 1974, Mariner 10 flew past Mercury, providing man a 5000 times closer look at this desolate, crater-pocked, sun-seared planet than had been possible from Earth. Using the gravitational field of its host planet to alter course, Mariner 10 flew out in a large elliptical orbit, circled back by Mercury a second time on 21 September 1974, and a third time on 16 March 1975. The cumulative evidence pictured a planet essentially unchanged since its creation some 4.5 billion years ago, except for heavy bombardment by meteors, with an iron core similar to Earth's, a thin atmosphere composed mostly of helium, and a weak magnetic field.
Fascinating as the information about our fellow voyagers in the solar system was and as important as the long-range scientific consequences might be, Congress and many government agencies were much more intrigued with the tangible, immediate-return, Earth-oriented program that began operations in 1972. On 23 July ERTS 1 (Earth Resources Technology Satellite) was launched into polar orbit. From that orbit it would cover three-quarters of the Earth's land surface every 18 days, at the same time of day (and therefore with the same sun angle for photography), affording virtually global real-time information on developing events such as crop inventory and health, water storage, air and water pollution, forest fires and diseases, and recent urban population changes. In addition it depicted the broad area (and therefore undetectable by ground survey or aircraft reconnaissance) geologic patterns and coastal and oceanic movements. ERTS 1 also interrogated hundreds of ground sensors monitoring air and water pollution, water temperature and currents, snow depth, etc., and relayed information to central collection centers in near real-time. The response was instantaneous and widespread. Foreign governments, states, local governments, universities, and a broad range of industrial concerns quickly became involved in both the exploration of techniques to exploit these new wide-area information sources and in real-time use of the data for pressing governmental and industrial needs. Some 300 national and international research teams pored over the imagery. For the first time accurate estimates were possible of the total planting and growth status of wheat, barley, corn, and rice crops at various times during the growing season; real-time maps versus ones based on data that would have been collected over a period of years; timber cutting patterns; accurate prediction of snow runoff for water management; accurate, real-time flood damage reports. Mid-term data included indications that the encroachments of the Sahara Desert in Africa could be reversed by controlled grazing on the sparse vegetation in the fringe areas; longer range returns suggested promise in monitoring strip mining and subsequent reclamation, and in identification of previously unknown extensions of Earth faults and fractures important to detection of potential earthquake zones and of associated mineral deposits.
Like the experimental communications satellites of the early 1960s, the ERTS found an immediate clientele of governmental and commercial customers clamoring for a continuing inflow of data. The pressure made itself felt in Congress; on 22 January 1975, Landsat 2 (formerly ERTS 2) was orbited ahead of schedule to ensure continuation of the data that ERTS 1 (renamed Landsat 1) had provided for two and a half years, and a third satellite was programmed for launch in 1977. This would give confidence to experimental users of the new system that they could securely plan for continued information from the satellite system.
The Earth resources program had another important meaning. It was a visible sign that the nature and objectives of the space program were undergoing a quiet but dramatic shift. Where the Moon had been the big target during the 1960s and large and expensive programs had been the name of the game, it became increasingly clear to NASA management as the decade ended that the political climate would no longer support that kind of a space program. The key question now was, "What will this project contribute to solving everyday problems of the person in the street?" One by one the 1960s-type daydreams of big, away-from-Earth projects were reluctantly put aside: a manned lunar base, a manned landing on Mars, an unmanned "grand tour" of several of the planets. When the Space Shuttle finally won approval, it was because of its heavy dedication to studies of our Earth and its convincing economies in operation.
Another sign of the times was that NASA was increasingly becoming a service agency. In 1970 NASA for the first time launched more satellites for others (ComSat Corp, NOAA, DoD, foreign governments) than for itself. Five years before only 2 of 24 launches had been for others. Clearly this trend would continue for some years.
Twilight for Apollo
Meanwhile Apollo was running its impressive course. Apollo 12 (1424 November 1969) repeated the Apollo 11 adventure at another site on the Moon, the Ocean of Storms. One attraction of that site was that Surveyor 3 had been squatting there for two and a half years. A pinpoint landing put the lunar module within 600 feet of the Surveyor spacecraft. In addition to deploying scientific instruments and collecting rock samples from the immediate surroundings, Astronauts Conrad and Bean cut off pieces from Surveyor 3, including the TV camera, for return to Earth and analysis after 30 months of exposure to the lunar environment.
Apollo 13 was launched 11 April 1970, to continue lunar exploration. But 56 hours into the flight, well on the way to the Moon, there was a "thump" in the service module behind the astronauts. An oxygen tank had ruptured. Pressure dropped alarmingly. What was the total damage? Had other systems been affected? How crippled was the spacecraft combination? The backup analysis system on Earth sprung into action. Using the meager data available, crews at contractor plants all over the country simulated, calculated, and reported. The verdict: Apollo 13 was seriously, perhaps mortally, wounded. There was not air or water or electricity to sustain three men on the shortest possible return path to Earth. But, ground crews and astronauts asked simultaneously, what about the lunar module, a self-contained spacecraft unaffected by the disaster? The lunar landing was out of the question anyway; the lifesaving question was how to get three men around the Moon and back to Earth before their life-supporting consumables ran out. Could the lunar module substitute for the command module, supplying propulsion and oxygen and water for an austere return trip? The simulations said yes. Apollo 13 was reprogrammed to loop around the Moon and set an emergency course for Earth return. The descent engine for the lunar module responded nobly; off they went back to Earth. It was a near thing --powered down to the point of minimum heating and communication, limiting activity to the least possible to save oxygen. Again the flexibility and depth of the system came to the rescue; when reentry was safely within the limited capabilities of the crippled Apollo, the "lifeboat" lunar module was jettisoned along with the wounded service module. Apollo 13 reentered safely.
The next flight was delayed while the causes and fixes for the near-tragedy on Apollo 13 were sorted out. On 31 January 1971, Apollo 14 lifted off, the beginning of the scientific exploration of the Moon. The major new system was a transporter, a cart on which to load equipment and bring back rock samples. A major target of the Apollo 14 mission to Fra Mauro was to climb the walls of the Cone Crater; the attempt was halted as time ran out and the astronauts had trouble pinpointing the location.
Apollo 15 introduced the Moon car, the lunar rover. With this electric-powered, four-wheel drive vehicle developed at Marshall at a cost of $60 million, the astronauts roamed beyond the narrow confines of their landing site and explored the area. Astronauts on this flight covered 17 miles of lunar surface, visited a number of craters in the Hadley-Apennines area, and photographed the ghostly ravine Hadley Rille. Thanks to the lowered exertion level because of the lunar rover, exploration time was doubled.
The remaining Apollo missions now had all the equipment planned for lunar exploration. Apollo 16 landed in the Descartes area in April 1972, stayed 71 hours, provided photos and measurements of lunar properties. Apollo 17, launched 7 December 1972, ended the Apollo program with the most productive scientific mission of the lunar exploration program. The site, Taurus-Littrow, had been selected on the basis of previous flights. Objectives were to seek out both oldest and youngest rocks to fill in the geologic history of the Moon. For the first time a trained geologist, Harrison H. Schmitt, was on a crew, adding his professional observations. EVA time was over 22 hours and the lunar rover traveled some 22 miles.
Apollo was ended. From beginning to end, it had lasted 11 1/2 years, cost $23.5 billion, landed 12 men on the Moon, and produced an unassessable amount of evidence and knowledge. Technologically it had produced hardware systems several orders of magnitude more capable than their predecessors. In various combinations, the components of this technology could be used for a wider variety of explorations than the nation could possibly afford. The luxury of choice was, which of a half-dozen possible missions?
Scientific answers were going to be returned over several decades. The Lunar Receiving Laboratory had been constructed in Houston to be the "archive" of the 840 pounds of physical lunar samples that had been returned from various parts of the Moon by six lunar landing crews. Scientists in this country and 54 foreign countries were analyzing the samples with an impressive variety of instruments and the expertise of many scientific disciplines. Gross results had already established that the Moon was a separate entity from Earth, formed at the same time as Earth some 4.5 billion years ago; that it had its own volcanic history; that with no protective atmosphere it had been bombarded for eons by meteors from outer space, which had plowed up the surface lava flows from the lunar interior. Refinement of data would go on for decades.
Apollo had proved many other things: the ability of a diversified system of government, industry, and universities to mobilize behind a common national purpose and produce on schedule an immense and diverse system directed to a common purpose. It not only argued that society could do many things in space, whether extended lunar exploration from permanent lunar bases or manned excursions to Mars, but argued that solutions to many of humanity's major problems on Earth --pollution, food supply, and natural disasters such as earthquakes and hurricanes could be ameliorated or controlled by the combination of space technology and the large-scale management techniques applied to it.
Next in manned spaceflight came Skylab. Trimmed back to one orbital workshop and three astronaut flights, Skylab had had a hectic financial and planning career, the converse of Apollo. The revised plan called for an S-IVB stage of the Saturn V to be outfitted as two-story orbiting laboratory, one floor being living quarters and the other working room. The major objective of Skylab was to determine whether humans could physically withstand extended stays in space and continue to do useful work. Medical data from the Gemini and Apollo flights had not completely answered the question. Since there would be far more room in the 89 foot long orbital workshop than in any previous spacecraft, William C. Schneider, Skylab program director, devised a more extensive experiment schedule than all previous spaceflights combined. Most ambitious in terms of hardware was the Apollo telescope mount; five major experiments would cover the entire range of solar physics and make it the most powerful astronomical observatory ever put in orbit. The other major areas of experimentation were Earth resources observations and medical experiments involving the three-man crew. There were important subcategories of experiments: the electric furnace, for example, would explore possibilities of using the weightless environment to perform industrial processes that were impossible or less effective on 1g Earth, such as forming perfectly round ball bearings or growing larger crystals, much in demand in the electronics industry.
On 14 May 1973 a giant Saturn V lifted off from Kennedy Space Center to place the unmanned 165,000 pound orbital workshop in Earth orbit. Within minutes after launch, disquieting news filtered through the telemetry reports from the Saturn V. The large, delicate meteoroid shield on the outside of the workshop had apparently been torn off by the vibrations of launch. In tearing off it had caused serious damage to the two wings of solar cells that were to supply most of the electric power to the workshop; one of them had sheared off, the other was snagged in the folded position. Once the workshop was in orbit, the news worsened. The loss of the big shade exposed the metal skin of the workshop to the hot sunshine; internal temperatures soared to 325 K. This heat not only threatened its habitation by astronauts, but if prolonged might fog sensitive film and generate poisonous gases.
The launch of the first crew was twice postponed, while the far-flung ground support team worked around the clock for 10 frantic days, trying to improvise fixes that would salvage the $2.6 billion program. With only partial knowledge of the precise degree and nature of the damage, engineers had to work out fixes that met the known problems, yet were versatile enough to cope with unknown ones. There were two major efforts: first, to devise a deployable shade that the astronauts could spread over the metal surface of the workshop; the other was to devise a versatile tool kit of cutters and snippers to release the solar wing from whatever prevented it from unfolding.
On 25 May 1973, an Apollo command and service module combination was lifted into orbit by a Saturn 1B. Apollo docked with the workshop on the 25th. The crew entered it the next day and deployed a makeshift parasol through the solar airlock. The effect was immediate; internal temperature began to drop. On 7 June Astronauts Conrad and Kerwin clambered outside the workshop and after a tense struggle succeeded in cutting the metal straps that ensnared the remaining solar wing; it slowly deployed and electrical power poured into the storage batteries. Human ingenuity and courage had made the workshop operational again.
The remaining Skylab missions were almost anticlimactic after the dramatic rescue of the workshop. With only minor problems, the missions ticked off their complicated schedules of experiments. In spite of the initial diversion, the first crew obtained 80 percent of the solar data planned; 12 of 15 Earth resources runs were completed; and all of the 16 medical experiments went as planned. Its 28-day mission completed, the crew undocked and returned to Earth.
The second crew was launched on 28 July 1973, completed almost 60 days in orbit, and exceeded by one-third the solar observations and Earth resources runs planned. All the medical experiments were performed. The third crew (launched 16 November 1973) completed an 84-day flight with all experiments performed, as well as the additional observations of the surprise cosmic visitor, comet Kohoutek.
The vast mass of astronomical and Earth resources data from the Skylab program would take years to analyze. A more immediate result was apparent in the medical data and the industrial experiments. With the corrective exercises available on Skylab, there seemed to be no physiological barrier to the length of time humans could survive and function in space. Biological functions did indeed stabilize after several weeks in zero-g. The industrial experiments gave strong evidence that the melting and solidification process was promisingly different in weightlessness; single crystals grew five times as large as those producible on Earth. Some high-cost industrial processes apparently had new potential in space.
As the empty Skylab continued to circle the Earth, its orbit began to decay, threatening an uncontrolled reentry. NASA regained some control over the rogue Skylab in the spring of 1979, and managed to steer it to reentry over the Indian Ocean. Still, chunks of the Skylab made a fiery plunge into remote areas of Australia, a reminder of the potential dangers of civilization's own debris from space.
Transonic and Hypersonic Flight Research
Although questions about an SST aircraft persisted, NASA and its principal contractor, Boeing, kept working on the design throughout the 1960s. By 1971, production plans were under way when the program came to a halt. Critics remained adamant about the costs of the SST and its ability to operate economically. Flight tests of the big XB-70 Valkyrie had done little to quell the issue of sonic booms, and there were worrisome questions about adverse environmental effects at high altitudes. Congress finally voted against funds for construction of an SST for flight testing.
The British and French proceeded with a smaller SST, the jointly developed Concorde, which began flight tests in 1969 and entered service in 1976. A Soviet SST, the Tupolev TU-144, also began internal schedules in 1976, but was withdrawn from service two years later. Meanwhile, NASA and American aerospace companies cooperated in a research effort known as the Supersonic Cruise Aircraft Research Program. Beginning in 1973, this activity involved analysis of propulsion systems and advanced airframes. Continuing into the 1980s, the ongoing SST studies made considerable progress in quieter, cleaner engines as well as much improved passenger capacity and operational efficiencies. If the opportunity for second-generation SST airliners materialized later, NASA and the aerospace industry intended to lead the way with an American design.
While investigation of the supersonic regime continued, a major breakthrough at the transonic level occurred --the supercritical wing. The transonic regime had beguiled aerodynamicists for years. At transonic speeds, both subsonic and supersonic flow patterns encased an aircraft. As the flow patterns went supersonic, shock waves flitted across the wings, resulting in a sharp rise in drag. With most commercial jet airliners operating in the transonic range, coping with this drag factor could bring major improvements in cruise performance and yield substantial benefits in operating costs.
During the 1960s, Richard Whitcomb committed himself to a program intended to resolve the transonic problem. For several years, Whitcomb intensely analyzed what came to be called the "supercritical" Mach number--the point where the airflow over the wing went supersonic, with a resultant decline in drag. Analysis and wind tunnel tests led to a wing with a flattened top surface (to reduce its tendency to generate shock waves) and a downward curve at the trailing edge (to help restore lift lost from the flattened top). But wind tunnel tests were one thing. Real planes in the air were often something else. The next step meant thorough flight testing of a plane equipped with the unusual wing.
Fortunately, NASA came up with an available plane that lent itself to comparatively easy modification: the Vought F-8A Crusader. The structure of the plane's shoulder-mounted wing made it easy to remove and replace with the supercritical design. Moreover, the F-8A was built with landing gear that retracted into the fuselage, leaving the experimental wing with no outstanding production encumbrances. The Navy had spare planes available, and its speed of Mach 1.7 made it ideal for transonic flight tests. Although the test plane had begun life as a Navy fighter, the supercritical wing program was aimed at civil applications. The airlines as well as the airline manufacturers closely followed development of the new airfoil.
The modified Crusader, designated the TF-8A, made its first flight at Edwards in 1971 and continued for the next two years. The test flights yielded data that corresponded to measurements from the preliminary tunnel tests at Langley. Most important, the supercritical wing promised genuine improvement in the transonic region, a fact that translated directly into reduced fuel costs and lower operational costs. Ironically, foreign manufacturers of business jets were the first to apply the new technology in new designs like the Canadair Challenger (Canada) and the Dassault Falcon (France). At the same time, both Boeing and Douglas applied the concept in experimental Air Force transports like the YC-14 and YC-15.
As additional commercial manufacturers began utilizing data from the supercritical wing studies, NASA and the Air Force collaborated in the development of its military applications for combat planes. Known as TACT, for Transonic Aircraft Technology, the military effort used a modified F-111A. By the early 1980s, with refined flight testing of the F-111A still continuing, several operational aircraft had been designed to utilize information from this project.
NASA's use of military aircraft to probe the transonic region paralleled a different effort that involved very high supersonic speeds. The aircraft in this case was one of the most exotic creations to fly --the Lockheed YF-12A, a highly classified interceptor design that led to the equally highly classified SR-71A Blackbird reconnaissance aircraft. According to published performance figures, the Blackbirds were capable of Mach 3 speeds at altitudes of 80,000 feet or more. The planes originated in the famed Lockheed "Skunk Works" of Clarence "Kelly" Johnson, where Johnson and a talented group of about 200 engineers put aeronautical pipe dreams on paper, and then proceeded to build and fly them. The operating requirements of the plane at extreme speeds and altitudes for sustained periods created a completely new regime of requirements for parts and systems. As Johnson commented later, "everything on the aircraft from rivets and fluids, up through the materials and power plants, had to be invented from scratch."
The first Blackbird flew in 1962; NASA first became involved in 1967, when Ames, where early wind tunnel data was acquired under tight security, was given permission to use the data in ongoing research. In return the Flight Research Center at Edwards organized a small team to assist the Air Force flight tests. But NASA wanted its own Blackbird for tests that would support the SST program still under way in the late 1960s. By this time, the SR-71A was operational, and the Air Force had put two YF-12A prototypes in storage at Edwards. When the Air Force offered the pair to NASA, the agency quickly accepted and also assumed operational expenses as well, although the Air Force assigned a small team for assistance in maintenance and logistics.
NASA launched its Blackbird program with great enthusiasm. Engineers from Lewis, Langley, and Ames had a keen interest in propulsion research, aerodynamics, structural design, and the accuracy of wind tunnel predictions involving Mach 3 aircraft. The first YF-12A test missions under NASA jurisdiction began late in 1969 and flights averaged once a week during the next 10 years, examining an impressive variety of high-speed problems. One series involved a biomedical team who monitored physiological changes in the flight crews in order to measure stress in the demanding environment of high-speed operations. Many Blackbird test flights routinely carried instruments to analyze boundary layer flow, skin friction, heat transfer, and pressures in flight. Various structural techniques were employed in test panels on the planes. An experimental computerized checkout system diagnosed problems in flight and provided information for required maintenance prior to the next mission. The checkout system was seen as a valuable one for application in the Space Shuttle as well as military and commercial planes.
In many ways, the Blackbird program, covering a decade of intensive flight tests, was one of the Flight Research Center's most useful programs, with a rich legacy of information for later aircraft built for sustained cruise at Mach 3. The end of the program prompted a chorus of protest from the Blackbird flight team and other NASA personnel who felt the United States was frittering away its lead in high-speed flight and in technology generally. Such grumbling was probably premature. The interest in aerospace and a national commitment to new technology was still high, although it took different directions. At first glance, the new concern for controlling aircraft noise, reducing pollutants from engines, and enhancing overall aircraft fuel efficiency might have seemed less glamorous than derring-do at Mach 3. But the rationale for confronting such issues became urgent in the late 1970s, and the solutions to these issues were no less complex and challenging than the problems of high-speed flight. Aeronautical research continued to be a dynamic field of NASA programs to come.