Precedents set by Mercury were visible in many different ways to the taxpayers who watched the plans for NASA's Gemini and Apollo programs take shape. Most obvious was the configuration of the two-man spacecraft that McDonnell was building for launches by the Martin Company's Titan II missile. The Gemini spacecraft was to be a far more sophisticated vehicle, with modular components easily accessible, with a lift/drag ratio provided by an offset center of gravity, with a real, if limited, orbital maneuvering capability, and with ejection seats instead of an escape pylon. Except for its doubled size, its countersunk viewports, and its lack of the escape tower, however, Gemini looked much like the familiar Mercury capsule.1
Plans and boilerplate models of the Apollo spacecraft - rather, of the so-called "command module" that would house three men in a tubby pyramid during launch and return to Earth, via the Moon - were being tested by airdrops from airplanes, by a second Little Joe (II) booster series, and by pad aborts using a tractor-rocket escape pylon. These and other evidences of Mercury's influence on design, development, testing, and training for more advanced space flights showed that NASA's new Manned Spacecraft Center and its Marshall, Kennedy, and Goddard Space Flight Centers were managed and staffed by most of the same personnel who had formed the original Mercury team. Growth and thoroughgoing organizational changes affected many individuals adversely, but the core of the Mercury team moved forward in the mid-1960s toward further exploitation of "lessons learned" from Mercury for manned space flight at large.2
It was primarily to hasten concentration on the accelerated manned space program and to move away from the "egg-shell" Mercury package and toward  more nearly "first-class" spacecraft accommodations that James E. Webb, Hugh L. Dryden, and Robert C. Seamans had decided against a fifth manned Mercury-Atlas mission. NASA administrators wanted to concentrate their engineering talent as soon and as completely as possible on the next major step toward the Moon. They realized the political and psychological risks of a lengthy delay before Americans again went into space, but they took these in stride as necessary to the longer range goals.3
The week after Mercury was officially terminated, the Soviet Union launched into orbit Vostok V, carrying Valery F. Bykovsky, and two days later Vostok VI, with "cosmonette" Valentina V. Tereshkova aboard. Both flights ended on June 19, 1963, after 81circuits by Bykovsky and 48 by Tereshkova. The flights followed slightly different orbital planes, exhibited no co-orbital maneuvers, and thus were similar to the tandem flights of Andrian Nikolayev and Pavel Popovich in August 1962. Tereshkova, trained as a parachutist and not as a pilot, became not only the first woman to go into space but also the first "layman," or non-pilot-engineer. When later she and Nikolayev were married and became parents, their healthy and normal baby seemed to indicate that fears about genetic damage from exposure to cosmic radiation were groundless.4
Most significantly, perhaps, Vostoks V and VI apparently signaled the end of the era of solo space flight. When the Soviets next sent men into space, on October 12, 1964, they began a new series with Voskhod I, which carried three men around Earth 16 times. And in 1965, the United States - taking what comfort it could, said one historian, from the fable of the tortoise and the hare - began its new Gemini series of twin- seated, maneuverable satellite missions, which were to make Mercury seem primitive indeed. When in March and June of that year Cosmonaut Alexei Leonov and Astronaut Edward H. White took their respective closely tethered "walks" - more nearly "swims" - in space, the fact that their command pilots were in the spacecraft to help in case of trouble seemed comforting.5 Neither cosmonauts nor astronauts were ever again likely to go into space alone in their machines. In this sense only, therefore, man's heroic age of solo space exploration may be said to have ended in June 1963.
Almost four months after the passing of Mercury and the last Vostok flights, and only a few weeks before the national shock of President Kennedy's assassination, NASA and its Manned Spacecraft Center held their formal, public postmortem on the first American manned satellite program. Staged on October 3 and 4, 1963, at the Music Hall in Houston and attended by some 1,300 people from NASA, the military, industry, and news media, this "Mercury Summary Conference" featured 20 papers on the overall program, with emphasis on Gordon Cooper's day-long MA-9 mission of May. Covering program management, booster performance, astronaut preparation, network operations, and MA-9 in-flight experiences and experiments, these papers constitute the best available technical overview of Project Mercury.6
The decorous proceedings were marred somewhat on the final day of the conference  by the appearance in newspapers throughout the country of a controversial story built around three pages of one report.7 In a paper on "Spacecraft Preflight Preparation," four MSC engineers from Florida sketched the nature and evolution of the intricate and exhaustive checkout procedures followed at the Cape after McDonnell's delivery of one of its capsules to the launch site. Discussing "quality assurance," the authors dwelled on the problem of component defects and malfunctions discovered by Mercury inspectors in industrial hardware. Inspections for MA-9 turned up 720 system or component discrepancies, 536 of which were attributed to faulty workmanship. "In Project Mercury," concluded the MSC authors, "thousands of man-hours were expended in testing, calibration, assembly, and installation of a variety of hardware that later failed to meet performance specifications or that malfunctioned during systems tests in a simulated space environment." And often these delays could have been avoided "if adequate attention to detail during manufacture or thorough inspection before delivery had been exercised."8
Although the import of this rather didactic engineering treatise was that the history of Mercury spacecraft prelaunch preparations presented a good object lesson in the rigorous demands for quality control and reliability testing before manned space flight - as opposed to missile, instrumented spacecraft, or even aircraft experience - journalists blew the implied criticism of McDonnell into a cause célèbre. "NASA blasts industry" was the general tenor of the news dispatches coming out of Houston. Coupled with the General Accounting Office's contemporaneous criticism of NASA and its contractors in the lagging Centaur program, the news coverage of the summary conference added some ammunition for attacks on the "great moondoggle."9
In a hurriedly called press conference in Houston and in hearings the next week before the House Committee on Science and Astronautics, NASA, MSC, and McDonnell leaders denied that any resentment or dissatisfaction existed because of anything in past or present NASA-McDonnell relations.10 Congress was satisfied, if the press was not, and this rather small tempest in a rather large teapot subsided quickly. The furor did suggest, however, that one of the lessons the Mercury technical staff had not learned well enough was extreme prudence in all public references to relations between NASA and its contractors and other agencies. Possibly the "candor at Canaveral" and elsewhere, for which the press had occasionally commended the Mercury team, would be the first casualty of the ongoing manned space effort.
In general, the authors of papers read at the Mercury Summary Conference, aware of the difficulty of making technological and administrative generalizations in the new and rapidly changing field of astronautics, offered only guarded conclusions about the significance of Mercury experiences for the Gemini and Apollo programs. But indirectly there, and more directly elsewhere, they did assess the state of the art and science of manned space flight, ask what Mercury had taught that might benefit Gemini and Apollo, and even venture some answers.11
 Project Mercury lasted 55 months, from authorization through the one-day mission, and while the earliest planned orbital mission slipped 22 months past its first scheduled launch time, Mercury achieved its original objectives with John Glenn's MA-6 flight only 40 months after formal project approval. Compared with either advanced missile or aircraft development programs, this was a good record; but many engineers denied the validity of such a comparison.
Mercury mobilized a dozen prime contractors, some 75 major subcontractors, and about 7200 third-tier sub-subcontractors, and vendors, all of whom together employed at most about two million persons who at one time or another had a direct hand in the project. In addition, the NASA complement on Mercury eventually reached 650 workers in the Space Task Group and Manned Spacecraft Center and 710 elsewhere in research and development support of the project. A conservative estimate of the maximum number of military servicemen and Defense Department personnel supporting an individual Mercury mission (both MA-6 and MA-9) counted 18,000 people, and another conservative estimate added 1,169 persons from educational and other civilian institutions. Thus, if the estimate of 1,817,000 workers employed by the Mercury vendors was too liberal and unrealistic, the total peak manpower figure of 2,020,528 was probably as accurate a figure as could be obtained.12
"Quick look" total cost estimates given at the summary conference in October 1963 showed that Mercury had cost $384,131,000 throughout the program, of which 37 percent went for the spacecraft, 33 percent for the tracking network, and 24 percent for launch vehicle procurement. Flight operations and "R and D" costs made up the remainder, as then estimated, but the final cost accounting was complicated by the unsettled conditions of closing and disposition costs and the mingling of Mercury and Gemini costs during 1962 and 1963. Through Glenn's flight, however, Mercury had cost about $300 million.13 Through Cooper's flight NASA estimated the grand total cost of Mercury at slightly more than $400 million (see Appendix F).
NASA engineers and physicians listed three primary "lessons learned" from their experience with Mercury for manned space flight. Their foremost medical objectives had been fulfilled, and the responses of two men in suborbit and four men in orbit had shown that human beings can function normally in space if adequately protected. Rather than acceleration g loads and weightlessness limiting man's capacity to fly in space, the men who flew Mercury seemed to adapt to "zero g" surprisingly well. The main medical problems were simple personal hygiene in flight, and the postflight readjustment symptom of orthostatic hypotension. Both appeared to be curable by technical developments rather than by preventive medicine.
Secondly, Mercury had proven that final launch preparations took far more time than anyone had anticipated in 1958 to ensure perfect readiness and reliability of the machines and men. NASA had had designed, therefore, an automated digital system for the future, called "ACE," for Acceptance Checkout Equipment,  to reduce human error in environmental chamber testing and the length of time required on the flight line at the Florida spaceport. Thirdly, mission control requirements, integrating the astronaut with his flight monitors and directors around the world, had grown to encompass the fullest utilization of real-time telemetry, tracking, computing, and display data. Nothing less would suffice for future missions. Two more acronyms came into use, "MCC" for the new Mission Control Center at Houston, and "GOSS" for Ground Operational Support Systems, reflecting the degree of complex automation being installed for positive ground control of future space flights.
Studying how they could improve on their performance for succeeding programs, NASA officials and engineers listed several other valuable technological and managerial lessons from Mercury. In spacecraft design, problems had been encountered with safety margins, redundancy, accessibility, shelf-life of parts, interchangeability, and with materials whose behavior under unfamiliar environmental conditions had not been wholly predictable. Regarding qualification of systems and components, there should be more analysis in an effort to make techniques "conservative, complete, integrated, and functional." Fabrication and inspection standards carried over from development into manufacturing work should be made still more "rigorous, detailed, current, and enforced." Engineers working for the Manned Spacecraft Center, both in Houston and at the Cape, called for continuous upgrading of tests, inspections, and other validation procedures, particularly with respect to interface compatibilities between systems. In configuration control, NASA manned space flight developers recognized their perennial weight control problem and their need to become more responsive, more familiar in detail, and more aware of danger signals in the production and fabrication phases of their business. And the managers of Mercury now acknowledged that methods of management that had worked well enough in the first American manned space project would not suit Gemini and Apollo, already in motion. They had only begun to use the sophisticated Program Evaluation and Review Technique, called "PERT," which had evolved from the Navy's experience in its nuclear submarine and Polaris missile development programs. Now PERT and other management tools, such as the incentive contract, would have to be exploited to the fullest extent practicable.14
Perhaps the most significant lesson learned from Mercury was that man was still invaluable to the machine. Mercury saw the evolution of the astronaut from little more than a passenger in a fully automatic system to an integral and fully integrated element in the entire space flight organism. By the end of the project, the Mercury capsule, instead of simply being a machine with a man in it, had truly become a manned space vehicle. Mercury Flight Director Christopher C. Kraft, an engineer, spoke for all exponents of manned space flight, irrespective of discipline: "Man is the deciding element. . . . As long as Man is able to alter the decision of the machine, we will have a spacecraft that can perform under any known conditions, and that can probe into the unknown for new knowledge."15
 Yet as Mercury faded farther into the past and Gemini and Apollo moved forward, some profound questions remained unanswered, and indeed usually not even asked.16 In the democratic society of the United States, did the formal commitment to costly space exploration, and especially the increased emphasis on manned space flight beginning in the Kennedy administration, actually represent a consensus among the electorate? The pace and chances for success of this country's drive toward spacefaring preeminence depended, finally, on the continued willingness of the American taxpayer to pay the bills. However divergent may have been the appeals of the two political parties in the 1964 Presidential election, neither the Republicans nor Democrats seriously questioned the existence of such a consensus.
Many more mundane problems plagued the times, some seeming so overwhelming as to demand dramatic and drastic solutions like those widely presumed to issue from space technology. But the arrival of the so-called "space age," heralded by Mercury astronauts and Vostok cosmonauts, did capture most men's imagination and did seem to dwarf the petty quarrels of men and nations. Vague hopes for future peace and prosperity accompanied public support of preparations  for two- and three-man spacecraft, but fears about the population explosion, nuclear proliferation, and social disparities made many wonder whether the manned space flight enterprise was worth the effort and the price. Why send two or three men to the Moon when two or three billion others remained rooted in human turmoil? Questions similar to this found traditional answers in terms of national security, scientific curiosity, economic benefits, and technological by-products, but ultimately the national commitment was an act of faith.
Still, many Americans, both technically literate and illiterate, doubted the return from the $400 million spent on Project Mercury and the vastly greater expenditures being allocated for succeeding manned space projects. A substantial portion of the scientific community agreed with Alvin M. Weinberg, Director of the Atomic Energy Commission's Oak Ridge National Laboratory, who argued that "most Americans would prefer to belong to a society which first gave the world a cure for cancer than to the society which put the first astronaut on Mars."17 Others deplored the fact that the American space effort was basically a "race to the Moon," having no nobler motivation than traditional nationalistic rivalry. Still others would confine the Nation's astronautical activities to unmanned instrumented space vehicles, thereby diminishing the cost of space exploration, as well as presumably avoiding the likely prospect that some day men would die in space.18
Nevertheless, whether most people in the United States approved or not, in the mid-1960s it seemed that not only American machines but selected and trained American citizens were in the space venture to stay. Project Mercury, leaving a legacy that perhaps was even more important psychologically than technologically, was already history. Hugh L. Dryden, only a few weeks before his death late in 1965, expressed his faith in manned space flight and offered a fitting epitaph for Project Mercury:
Man is distinguished from other forms of life by his powers of reasoning and by his spiritual aspirations. Already the events of the last seven years have had profound impact on all human affairs throughout the world. Repercussions have been felt in science, industry, education, government, law, ethics, and religion. No area of human activity or thought has escaped. The toys of our children, the ambitions of our young men and women, the fortunes of industrialists, the daily tasks of diplomats, the careers of military officers, the pronouncements of high church officials - all have reflected the all-pervading influence of the beginning steps in space exploration The impact can only be compared with those great developments of past history like the Copernican theory which placed the Sun, rather than the earth, at the center of our solar system; to the work of Sir Isaac Newton in relating the fall of an apple to the motion of the moon around the earth through the universal law of gravitation; to the industrial revolution; or to other great landmarks in the history of mankind.19
1 McDonnell Aircraft Corp., NASA Project Gemini-Familiarization Manual (preliminary), SEDR 300, June 1, 1962, passim. See also Ralph O. Shankle, The Twins of Space (Philadelphia, 1964); and Charles W. Mathews, "Project Gemini - Status and Plans," paper, 25th annual Aerospace Writers' Assn. Convention, Dallas, Tex., May 24, 1963.
2 E.g., North American Aviation, Inc., The Apollo Spacecraft, Space and Information Systems Division, May 15, 1964; NASA Project Apollo working paper No. 1015, Project Apollo: Space Task Group Study Report, February 15, 1961, edited by H. Kurt Strass; NASA MSC fact sheet No. 292, "Apollo Program," June 1965; Walter Sullivan, ed., America's Race for the Moon: The Story of Project Apollo (New York, 1962).
3 Robert C. Seamans, Jr., Hugh L. Dryden, and James E. Webb, interviews, Washington, D.C., Aug. 31, Sept. 3, 1965.
4 See Astronautics and Aeronautics, 1963: Chronology on Science, Technology, and Policy, NASA SP-4004 (Washington, 1964), 241, 244, 376, 417, 505, 506; and Astronautics and Aeronautics, 1964: Chronology on Science, Technology, and Policy, NASA SP-4005 (Washington, 1965), 209, 248.
5 Ibid., 348, 458; Oscar Theodore Barck, Jr., and Nelson Manfred Blake, Since 1900: A History of the United States in Our Times (4th ed., New York, 1965), 877; NASA Office of Educational Programs and Services, pamphlet, "Gemini 4 Extravehicular Activity: A Walk in Space," July 1965.
6 Mercury Project Summary, Including Results of the Fourth Manned Orbital Flight, May 15 and 16, 1963, NASA SP-45 (Washington, 1963).
7 Ibid., 247-249, part of the paper by J. C. Moser, G. M. Preston, J. J. Williams, and A. E. Morse, Jr.
8 Ibid., 248. For a similar discussion of quality control for the launch vehicle, see "Manufacturing and Process Controls" in Proceedings of the Mercury-Atlas Booster Reliability Workshops, General Dynamics/Astronautics, San Diego, July 12, 1963, 1-56.
9 See House Committee on Science and Astronautics, 88 Cong., 1 sess. (1963), Briefing on NASA Reorganization: Project Mercury Summary, 18-36. See also John W. Finney, "Contractors Cited for an Average of 10 Failures on Each Space Trip," New York Times, Oct. 4, 1963; and Edwin Diamond, The Rise and Fall of the Space Age (Garden City, N.Y., 1964), 32-46.
10 Warren Burkett, "NASA Brass Pays Tribute to Industry," Houston Chronicle, Oct. 4, 1963; and New York Times, Washington Post, and Washington Evening Star, Oct. 5, 1963.
11 See William M. Bland, Jr., and Lewis R. Fisher, "Project Mercury Experience," paper, Aerospace Writers' Assn., Dallas, May 24, 1963; Walter C. Williams, "The Mercury Textbook," paper, American Institute of Aeronautics and Astronautics, Los Angeles, June 17, 1963, MSC fact sheet No. 197; Christopher C. Kraft, Jr., "A Review of Knowledge Acquired from the First Manned Satellite Program," MSC fact sheet No. 206; and Wesley L. Hjornevik, "NASA Programs and Their Management," paper, Harvard Business School Club of Houston, Jan. 28, 1964, MSC fact sheet No. 235.
12 See Mercury Project Summary, 24-26; cf. MSC, "Briefing Materials," prepared for Dr. Robert C. Seamans and Dr. George E. Mueller, Sept. 20-21, 1963 (2 vols., conf.).
13 Ibid., See also Senate Committee on Aeronautical and Space Sciences, 87 Cong., 2 sess. (1962), Staff Report, Manned Space Flight Program of the National Aeronautics and Space Administration: Project Mercury, Gemini, and Apollo, 7.
14 "Briefing Materials"; Bland and Fisher, and Hjornevik papers.
15 Fact sheet No. 206, 9. Cf. Robert B. Voas, "The Case History of a Spacecraft (Mercury Project)," MSC fact sheet No. 117, Feb. 5, 1963.
16 For a few intimations of these questions, see "Our Gamble in Space," special issue of The Atlantic, CCXII (August 1963); Lewis Mumford, "Authoritarian and Democratic Technics," Technology and Culture, V (Winter 1964), 1-8; Melvin Kranzberg, "The Inner Challenge of Outer Space," paper, University of Houston Lecture-Artist Series, March 3, 1965.
17 See Alvin M. Weinberg, quoted in James L. Penick, et al., eds., The Politics of American Science: 1939 to the Present (Chicago, 1965), 221. See also Weinberg, "Criteria for Scientific Choice," Minerva (Winter, 1963), 159-171.
18 See, for example, Joseph Wood Krutch, "Why I Am Not Going to the Moon," Saturday Review, XLVIII (Nov. 20, 1965), 29-31; and Philip H. Abelson, Saturday Review, idem.
19 Hugh L. Dryden, "The Nation's Manned Space Flight," address, Governor's Conference on Oceanography and Astronautics, Kauai, Hawaii, Oct. 1, 1965, 3-4.