For some time, the development phase of Gemini and Apollo proceeded along parallel lines, leading to a belief in some quarters that efforts devoted to Gemini were sapping Apollo's energies. Sporadically, throughout the years, a spirit of competition grew within Gemini - a feeling that its spacecraft could do more, its missions could be extended, perhaps even to lunar flight. But within Apollo doubts were increasing. Gemini had been justified partly on the basis of its contribution to Apollo experience. In 1965, Howard Tindall, whose specialty was mission planning and who had achieved local fame with his "Tindall grams," tried to look at the question objectively and concluded that hardware and mission planning were too difficult and too concurrent for either program office to keep up with or help the other.1
As for the early days, Tindall's viewpoint was probably correct. Gemini had too many financial and technical problems of its own to leave much energy to worry about Apollo. Nor was the Apollo office,  with its two dissimilar spacecraft, quite as cohesive an organization as it might have thought. Lunar module engineers found it equally difficult to get meaningful assistance from either Apollo command module or Gemini spacecraft people - and, no doubt, vice versa. No problem that arose on one spacecraft appeared quite like those encountered on the other two and no one had the time to consider the problems dispassionately and apply them to their counterparts in a practical manner.2
Once Gemini neared its operational phase, however, things were different. Apollo managers and engineers quickly sought help in various areas. James Church wanted to learn about Gemini program control experience, especially when the Gemini people succeeded in controlling program costs. Calvin Perrine asked for information on ground test programs as the Gemini development and test experts began meeting delivery schedules more successfully. Rolf Lanzkron and Joseph Loftus were anxious to learn anything from the Gemini crews that might be applicable to Apollo flight problems. Even North American, the Apollo command module manufacturer, thought some of Gemini's checkout experience might be helpful.3 Both North American and Grumman (the lunar module builder) had already requested manufacturing assistance from the Gemini spacecraft contractor, at one time causing William Lee, a deputy manager in the Apollo office, to caution them not to "convert McDonnell from a spacecraft manufacturer into an educational institution."4
Although Lee's point may have been intentionally overdrawn, Gemini manufacturing, testing, and review procedures did influence Apollo. By August 1965, many of these methods were being drawn upon to smooth the flow of hardware through the factory and on to the launch site. Of course, Gemini built upon some experience derived from Mercury - the same company manufactured the spacecraft and the same NASA group managed the project - but modular, accessible, serviceable Gemini was far more suitable for developing a systematic, if not routine, approach to getting it built, out of the factory, and onto the pad ready for launch. Gemini's vehicles, whose designers had avoided Mercury's interlocking systems, left the contractor plants much as airplanes did - all tested and nearly ready to fly. Cape Kennedy became a checkout and launch activity for Gemini, instead of the test and modification center it had been during Mercury.5
Besides the manufacturing and testing procedures, Gemini came to grips with several specific systems, common in one form or another to Apollo, that were new to space flight operations. Spacecraft thrusters powerful enough to alter the flight path several times and fuel cells to generate electrical energy to run the systems represented particularly impressive advances in aerospace technology. In addition, Gemini spacecraft were equipped with a computer and a radar to aid in solving the rendezvous problem. All of these systems went through  troubled development and qualification periods and, in most cases, required extensive redesign. More often than not these difficulties came to the attention of NASA's top administrators. Problem-solving boards, headed by senior officials, were appointed and armed with characters to draw upon organizations and facilities in government and industry to bring about solutions. Those areas that yielded most stubbornly were aired at Gemini and Apollo executive meetings attended by NASA administrators and their staffs and company presidents and their aides - the people in charge who could bring pressures and resources to bear to fix thrusters, fuel cells, Agenas, or other recalcitrant systems.6
Several management bodies spawned during Gemini were not constrained to one-shot, fix-it functions but were formalized and adapted to whatever program followed. One of the more important of these dealt with manned space flight experiments. As in other cases, this activity had its origins in Project Mercury, albeit to a very limited degree. Only a few scientists gained a nodding acquaintance with NASA and industry aerospace technologists; and there had not been much interest on either side in changing that situation. Engineers had concentrated on making Mercury work and most scientists had preferred to have their experiments ride aboard NASA's unmanned satellites. In the summer of 1963, however, science gained a permanent foothold in manned space flight operations. When the demise of the paraglider* left some unoccupied space in the vehicle, a few NASA officials saw a chance to set up an experiments program in orderly fashion. Homer E. Newell, Director of NASA's Office of Space Sciences, sent letters to more than 600 scientists, describing Gemini and inviting proposals. When the response was good, NASA established a Manned Space Flight Experiments Board in January 1964. By the fourth Gemini flight - the second manned - experiments and principal investigators had been worked into mission operations with fair success; by the last flight, procedures had been sharpened sufficiently for the board to continue in Apollo, and later in Skylab, without a break in stride.7
One of the quicker ways Gemini grabbed Apollo's attention, though certainly not planned that way, was its nearly catastrophic anomalies. Perhaps the most significant example was the explosion of Gemini Agena target vehicle 5002 in October 1965. The solution - to inject oxidizer into the firing chamber before the fuel - was applied to the lunar module's ascent engine simultaneously with the modifications to the Agena's primary propulsion system.8  Visions of astronauts on the lunar surface igniting their takeoff engine only to have it explode were too harrowing to be entertained.
But there were day-to-day Apollo-Gemini exchanges that did not relate to specific incidents. For example, people from the Flight Crew Support and Crew Systems Divisions worked on astronaut equipment and space suits to achieve a range of capabilities from extravehicular activity to shirtsleeve cabin operations - features of definite value to Apollo. Perhaps the group that gained the most insight into the routine operations of the two program offices was flight control. Christopher Kraft, who directed this activity, had been largely responsible for planning the old Mercury Control Center. Much improvising had been necessary to complete that project, and the facility was obviously totally inadequate to support Gemini and Apollo. NASA decided to build a control center in Houston, the new home of the Manned Spacecraft Center, and based this decision, in part, on the reasoning that flight control and spacecraft design would profit from having engineers from these two areas working together. Kraft concentrated first on Gemini requirements, partly because of manpower limitations and time constraints (Gemini would fly sooner), but mainly because of the need for Gemini experience in qualifying men, flight control equipment, and procedures to handle the far more complex missions of Apollo.9
Long before mission operations commenced, Kraft and his group foresaw that Gemini and Apollo flight control would require large numbers of systems, network, and trajectory specialists. Staff rooms, housing experts in these categories, were arranged around the mission operations control room. The new control center was not needed for the first two Gemini manned missions, but Kraft wanted to, and did, get it set up and operating one flight before any rendezvous maneuvers, practice or otherwise, were scheduled to take place. Kraft led his flight control team through the first rendezvous mission, as he had intended, and then withdrew to apply, in preparing for Apollo, the lessons he had learned. A major area on which he focused attention was the computer complex. Although the IBM 7094 model then in use was adequate for Gemini, it was better suited to scientific purposes. What Apollo needed, Kraft said, was a second generation model capable of supporting realtime space operations.10 He was proved right when the flight controllers were able to change Apollo 13, in the middle of the mission, from a lunar landing to a circumlunar flight and thus to prevent a space tragedy.
Beginning with Gemini's sixth flight, Apollo personnel watched mission operations more closely, attending panel meetings on spacecraft systems and mission planning, observing flight control operations, and participating in mission debriefings and evaluations. On occasions when Gemini planners reacted to anomalies with a seizure of conservation, Apollo engineers pressed to make mission activities more meaningful to the lunar program.  When things really went wrong - the GATV 5002 explosion, the shutdown of Gemini launch vehicle 6 after ignition, and the stuck thruster on Spacecraft 8 - systems engineering experts were assigned to determine how similar incidents might, or might not, affect Apollo.11
The Gemini program citing to its original flight schedule much more closely than had Mercury. Eighteen months was the lag time for the first manned Gemini mission;** the final mission, nine flights later, was still 18 months behind the schedule approved in January 1962. In contrast, the first manned orbital Mercury mission came 22 months later than scheduled, and the final mission, only three flights later, lagged more than 32 months. Mercury's period of orbital operations covered 451 days, or a flight every 112 days, to accumulate only 55 hours of crew experience. The 10 manned Gemini flights spanned 603 days, or a flight every 60 days, to accumulate 970 mission-hours and 1940 man-hours in space. Sixteen different astronauts made Gemini flights and four others trained for them. This experience was passed on to Apollo, as 15 of the 20 men subsequently flew in the lunar program. The rapid succession of Gemini missions demonstrated that it was truly a second generation spacecraft, and the length of its missions - 330 hours on Gemini VII - allayed major medical concerns over man's ability to adapt to and function in space. More and more it became an accepted fact during Gemini that man could, should, and would fly to the Moon and back.12
Projects Mercury and Gemini certainly had one feature in common - both cost about double the original estimate. The best educated guess that T. Keith Glennan, the first NASA Administrator, could give for Mercury was $200 million, and its price was over $400 million at the end. Gemini started at $531 million to build what was supposed to be an improved Mercury and wound up costing $1.147 billion to cover a program that included many new developments. Unlike Mercury, Gemini had its share of financial crises; Congress and the Administration, beset with a variety of domestic and international problems, curbed the flow of money to NASA - and Gemini usually had to bear the brunt. At times the prospects must have seemed bleak to the engineers who worked on it, but the monetary cuts were never deep enough to preclude, although they often threatened, the accomplishment of Gemini's primary objectives. In what must be counted an unusual circumstance at the leading edge of technology, Gemini actually rolled back the money tide to some extent. The projected runout cost in Fiscal Year 1964 had been set at $1.354 billion, but the innovation of better test and checkout procedures that same year cut two months  from the schedule and saved an estimated $200 million. Major credit for this achievement should probably go to the incentive contracts that in 1964 put Gemini procurement on a strikingly new footing.13
By putting manned space flight on a more routine basis, as stated in the project development plan, the rapid and successful progression of Gemini missions had a salient effect on American and international opinion - manned space flight became commonplace. During the flight period, there had been a spacecraft circling Earth about six percent of the time or, theoretically, an hour and a half for each one of the 603 days the operations covered. Not even the Wright brothers, at the dawn of powered flight, could have sustained public interest on such a regular basis. Over a thousand reporters came to Houston for Gemini IV, drawn by the knowledge that the new mission control center would operate for the first time and by predictions in some medical circles that the astronauts might die after being in weightless flight so long. No succeeding flight drew nearly as many until Apollo 11, when over a thousand reporters, cameramen, commentators, and technicians again descended on Houston, this time to write and talk about the lunar landing mission.
Gemini VII/VI-A, the first rendezvous mission, not only gave new life to the old saw about not being able to tell the players without a program (with four men and two spacecraft cluttering up the heavens) and proved that a 14-day flight was feasible, but it saw the Russian-American space race scorecard all but tossed aside. The fact that the Russian cosmonauts did not fly at all while American astronauts whirled about Earth at frequent intervals probably prompted the premise that the race was over. Now that the United States had gained space preeminence and international tensions seemed to be lessening despite Vietnam, the value of manned space flight was increasingly questioned when compared to the need for solving the age-old problems of hunger, housing, and education.14
The final event in the Gemini program took place in Houston on 1-2 February 1967, as planned, in the Manned Spacecraft Center auditorium. Some 900 people gathered from throughout the country to be greeted by Director Robert Gilruth, who asked them to divorce the recent Apollo accident from the Gemini proceedings. During the two-day conference, 21 technical papers were presented, concentrating mainly on rendezvous, extravehicular activity, and experiments.15
Although the summary conference was given little space by the news media, Gemini's lessons and its people, some in leadership roles, were significant factors in Apollo's recovery. Twenty-two months elapsed before America put men into space again, yet only nine months after that - in July 1969 - two astronauts walked on the Moon and ten more soon followed in their steps. Gemini had contributed its share to man's quest for a better understanding and use of his environment.  As it developed the gaze was not wholly outward to the stars. Beginning with Gemini's manned missions,scientists gradually realized that photographs of Earth brought back by the astronauts could serve as a valuable tool to help identify and husband Earth's dwindling resources. Perhaps future historians will see that as Gemini's most lasting contribution.
* Setting down on land was one goal that Gemini failed to achieve. Ironically, in 1965 there were some near-perfect tests with a limp (as opposed to an inflatable) version of the paraglider. By that time, however, the device was too far out of phase with Gemini schedules.
** These scheduling figures are based on the early scheme of having only one unmanned flight in the program; the second would have carried a crew.
1 Memo, Howard W. Tindall, Jr., to Chief, Mission Planning and Analysis Div., "Can Gemini contribute to Apollo?" 8 Jan. 1965.
2 William F. Rector III, interview, Redondo Beach, Calif., 27 Jan. 1970.
3 Courtney G. Brooks, James M. Grimwood, and Loyd S. Swenson, Jr., "Chariots for Apollo: A History of Lunar Spacecraft," draft, 1976, p. 349, note.
4 Memo, William A. Lee to ASPO Div. Chiefs, Asst. Div. Chiefs, and Br. Chiefs, "Data Exchange Meetings with McDonnell Aircraft Corporation," PA/M9-65-252, 27 Sept. 1965.
5 NASA OMSF Apollo Program Directive No. 6, "Sequence and Flow of Hardware Development and Key Inspection, Review, and Certification Checkpoints," 12 Aug. 1965.
6 TWX, George M. Low to MSC, Attn: James C. Elms, "Apollo and Gemini Fuel Cells," M-C S 1000.578, 7 Oct. 1963; memo, André J. Meyer, Jr., to MSC Historical Office, "Comments on Draft Chapters 7 and 8 of Gemini Narrative History," 6 Jan. 1972; William C. Schneider, interview, Washington, 23 Jan. 1967.
7 Grimwood, "Planning the Experiments," unpublished draft chapter of Gemini history, 31 July 1968; memo, George E. Mueller to Mac C. Adams, no subj., 20 Oct. 1965; memo, Adams to Assoc. Adm., Manned Space Flight, "Possible application of limp paraglider to Apollo," n.d.; Robert R. Gilruth, conversation with Grimwood, 18 Aug. 1972.
8 Memo, William A. Lee to Low, "LEM Ascent Engine Fuel Lead, " 11 April 1966.
9 Christopher C. Kraft, Jr., interview, Houston, 5 Oct. 1967.
11 Letter, Samuel C. Phillips to MSFC, Attn: Saturn V Program Mgr., "Application of Gemini Experience to Apollo," 7 April 1966, with enclosures; letter, Phillips to MSC, Attn: Mgr., GPO, "Gemini/Apollo Launch Vehicle Meeting," 15 Sept. 1966.
12 Appendixes B and C, this volume; Loyd S. Swenson, Jr., James M. Grimwood, and Charles C. Alexander, This New Ocean: A History of Project Mercury, NASA SP-4201 (Washington, 1966), Appendix D; memo, Hugh L. Dryden, Cabinet Report to the President, "Significance of Gemini V Accomplishments," 11 Sept.1965; "Project Gemini Schedule Analysis," GPO, 5 Jan. 1962.
13 Appendix E, this volume; Swenson, Grimwood, and Alexander, This New Ocean, Appendix F; letter, Paul E. Purser to Grimwood, 12 June 1974.
14 Appendix B, this volume; MSC Public Affairs Office accreditation lists, Gemini IV through Apollo 11; "World Press Reaction to Gemini VI and VII," United States Information Agency Research and Reference Series R-189-65, 22 Dec. 1965.
15 Gemini Summary Conference, SP-138 (Washington, 1967); Jim Maloney, "Gemini Conference Delegates Silenced about Apollo Fire," The Houston Post, 2 Feb. 1967.