(Updated February 13, 2006) Project Mercury is now history. In its short span of four years, eight months, and one week as the Nation's first manned space flight program, Mercury earned a unique place in the annals of science and technology. The culmination of decades of investigation and application of aerodynamics, rocket propulsion, celestial mechanics, aerospace medicine, and electronics, Project Mercury took man beyond the atmosphere into space orbit. It confirmed the potential for man's mobility in his universe. It remains for Projects Gemini and Apollo to demonstrate that potential. Project Mercury was not only a step in the history of flight technology, it was a major step in national commitment to space research and exploration and to man's struggle to fly. One has only to contrast it with the Wright Brothers' achievements of sixty years ago, when two meticulous men, with a bicycle shop, a handmade wind tunnel, determination and industriousness, and little financial means or support, accomplished controlled, powered flight. The austere contrast of the Wrights or of Professor Goddard's rocket work with today's Government-sponsored, highly complex space program, involving thousands of persons and hundreds of Federal, industrial, and university activities, is eloquent testimony to the new prominence of science and technology in our daily lives. The evolution and achievements of Project Mercury offer an outstanding example of a truly national effort in the advancement of knowledge and its application. The Project Mercury story must be examined in the full context of its fundamental features - scientific, engineering, managerial - in the dynamic human environment of national and international life. Indeed, the national commitment to Project Mercury and its successors requires a valid perspective on the potential accomplishments of science and technology as well as on the response of a democratic society to the challenges of its day. This chronology of Project Mercury represents only a beginning on the full history, just as Mercury was only a first step in the development of American space transportation. No chronology is a history. This volume is but a preface to what is yet to come. Yet it offers us a catalog of processes by which man progresses from ideas originating in the human mind to the physical devices for man's travel to the moon and beyond.

Project Gemini was the United States' second manned space flight program, a bridge between the pioneering achievement of Project Mercury and the yet-to-be realized lunar mission of Project Apollo. This Chronology, a step in preparing the history of Project Gemini, marks the completion of the first phase of the study of the Gemini program and lays the foundation for the narrative history that will follow. What we have done must stand as an independent work in its own right. But at the same time, some of its characteristics- in particular, what it contains and what it omits- can be properly justified only in terms of the larger whole of which it is a part. We have deliberately focused this Chronology very narrowly, excluding much material of undoubted relevance to the background of events, the context of decision, and to other matters that might be characterized as the external environment of Project Gemini. In part this is the inevitable result of a chronological format, which leaves little scope for explaining and interpreting events. Equally important, however, was our decision to reserve for the less restricted confines of a subsequent narrative history our confrontation with the subtle problems of interpretation and causation, of controversy and cooperation, of individual achievements and failures in the Gemini program. Several major features of this text grew directly from this decision. Our orientation throughout has been primarily institutional. Organizations rather than individuals are ordinarily the actors in events as we describe them. The point of view embodied in most of the entries is that of Gemini Program Office (the Manned Spacecraft Center element created to carry through the Gemini program) and of major Gemini contractors. The events that we have been most concerned to elucidate are technological - the engineering and developmental work which transformed the concepts and objectives of the Gemini program from idea to reality. This Chronology is fully documented, with sources for each entry in the text cited immediately after the entry. Our greatest, though not exclusive, reliance has been on primary sources. Of these, perhaps the most widely useful have been the various recurring reports issued by both NASA and contractor organizations. Foremost among these are the Project Gemini Quarterly Status Reports, the Manned Spacecraft Center weekly and monthly activity reports and contractor monthly progress reports. Another extremely useful class of materials comprises nonrecurring reports and documents, such as working papers, technical reports, statements of work, mission reports and analyses, familiarization manuals, and final reports. The third major body of sources consists of the records of various NASA organizations, particularly Gemini Program Office records. These include notes, minutes and abstracts of meetings, official correspondence, telegrams, memorandums, reading files, and the like. The most significant achievements of Gemini involved precision maneuvering in orbit and a major extension of the duration of manned space flights. These included the first rendezvous in orbit of one spacecraft with another and the docking of two spacecraft together. The docking operation allowed the use of a large propulsion system to carry men to greater heights above Earth than had been previously possible, thereby enabling the astronauts to view and photograph Earth over extensive areas.

A detailed, yet highly readable book, On the Shoulders of Titans should be the starting point for all who are interested in the basic history of the Gemini Program. NASA's second human spaceflight program, Gemini laid the groundwork for the more ambitious Apollo program which put astronauts on the Moon.

Apollo was America's program to land men on the moon and get them safely back to the earth. In May 1961 President Kennedy gave the signal for planning and developing the machines to take men to that body. This decision, although bold and startling at the time, was not made at random nor did it lack a sound engineering base. Subcommittees of the National Advisory Committee for Aeronautics (NACA), predecessor of the National Aeronautics and Space Administration (NASA), had regularly surveyed aeronautical needs and pointed out problems for immediate resolution and specific areas for advanced research. After NASA's creation in October 1958, its leaders (many of them former NACA officials) continued to operate in this fashion and, less than a year later, set up a group to study what the agency should do in near earth and deep space exploration. Among the items listed by that group was a lunar landing, a proposal also discussed in circles outside NASA as a means for achieving and demonstrating technological supremacy in space. From the time Russia launched its first Sputnik in October 1957, many Americans had viewed the moon as a logical goal. A two-nation space race subsequently made that destination America's national objective for the 1960s. America had a program, Project Mercury, to put man in low-earth orbit and recover him safely. In July 1960 NASA announced plans to follow Mercury with a program, later named Apollo, to fly men around the moon. Soon thereafter, several industrial firms were awarded contracts to study the feasibility of such an enterprise. The companies had scarcely finished this task when the Russians scored again, orbiting the first space traveler, Cosmonaut Yuri Gagarin, on 12 April 1961. Three weeks later the Americans succeeded in launching Astronaut Alan Shepard into a suborbital arc. These events and other pressures to get America moving provided the popular, political, and technological foundations upon which President Kennedy could base his appeal for support from the Congress and the American people for the Apollo program. The Apollo story has many pieces: How and why did it start? What made it work? What did it accomplish? What did it mean? Some of its visible (and some not so visible) parts the launch vehicles, special facilities, administration, Skylab program, Apollo Soyuz Test Project, as examples, have been recorded by the NASA History Office and some have not. A single volume treating all aspects of Apollo, whatever they were, must await the passage of time to permit a fair perspective. At that later date, this manuscript may seem narrow in scope and perhaps it is. But among present readers, particularly those who were Apollo program participants there are some who argue that the text is too broad and that their specialties receive short shrift. Moreover, some top NASA leaders during Apollo's times contend, perhaps rightly, that the authors were not familiar with all the nuances of some of the accounts set down here. Chariots for Apollo: A History of Manned Lunar Spacecraft begins with the creation of NASA itself and with the definition of a manned space flight program to follow Mercury. It ends with Apollo 11, when America attained its goal of the 1960s, landing the first men on the moon and returning them to the earth. The focal points of this story are the spacecraft the command and service modules and the lunar module.

Gemini was the intermediate manned space flight program between America's first steps into space with Mercury and the amazing and unprecedented accomplishments achieved during the manned lunar expeditions of Apollo. Because of its position between these two other efforts, Gemini is probably less remembered. Still, it more than had its place in man's progress into this new frontier. Gemini accomplishments were manyfold. They included many firsts: first astronaut-controlled maneuvering in space; first rendezvous in space of one spacecraft with another; first docking of one spacecraft with a propulsive stage and use of that stage to transfer man to high altitude; first traverse of man into the Earth's radiation belts; first extended manned flights of a week or more in duration; first extended stays of man outside his spacecraft; first controlled reentry and precision landing; and many more. These achievements were significant in ways one cannot truly evaluate even today, but two things stand out: (1) it was the time when America caught up and surpassed the Soviet Union in manned space flight, and (2) these demonstrations of capability were an absolute prerequisite to the phenomenal Apollo accomplishments then yet to come. Project Gemini is now little remembered, having vanished into that special limbo reserved for the successful intermediate steps in a fast-moving technological advance. Conceived and approved in 1961, the second major project in the American manned space flight program carried men into orbit in 1965 and 1966. Gemini thus kept Americans in space between the path-breaking but limited Earth-orbital missions of Project Mercury and the far more ambitious Project Apollo, which climaxed in 1969 when two men first set foot on the Moon. This book is a detailed history of the failures and victories of the Gemini program.