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DESTINATION MOON: A History of the Lunar Orbiter Program


CHAPTER XI: CONCLUSIONS: LUNAR ORBITER'S CONTRIBUTION TO SPACE EXPLORATION

A Meaning for the Lunar Orbiter Achievements



[321] Doubtless much more can be said about the Lunar Orbiter Program and its relationship to Apollo. However, this must be the task of future historians of space exploration. It now remains for this author to draw his conclusions about the Lunar Orbiter Program. These are certainly preliminary, and any error must be attributed to the author.
The Lunar Orbiter Program, like the Apollo Program, had unfolded in a politically charged atmosphere. The national commitment to land Americans on the Moon within the decade of the sixties imposed certain directions and a sense of urgency on the course which the National Aeronautics and Space Administration took in both programs. It also placed certain limitations on unmanned exploration of the Moon. First, the Apollo Program provided Lunar Orbiter with its raison d'être. This meant that the Office of Space Science [322] and Applications undertook an engineering feat in 1963 whose most immediate applications would directly support the objectives of the Apollo Program, to design and build a system and a mission that could take men to the Moon and return them safely to Earth. Lunar Orbiter contributed significantly to Apollo mission design (the hardware been designed and built before the Lunar Orbiter mission operations began). In this it supplemented the pioneering work of Ranger and Surveyor.
The American commitment for a manned lunar landing and the needs of Apollo eclipsed unmanned scientific exploration of the Moon during the sixties. The Office of Space Science and Applications thus also stood in the shadow of the Office of Manned Space Flight in lunar exploration. On the other hand, OMSF owed OSSA a debt of gratitude for the ground-breaking, precursory work that Ranger, Surveyor, and Lunar Orbiter did. Moreover, the highly successful Lunar Orbiter Program proved the role that unmanned, long-life orbiters could play in future space exploration. It is no coincidence that Langley Research Center, which directed the Lunar Orbiter Program, was in 1976 carrying out the operational phase of the Viking Mars program, with two Viking spacecraft on their way to orbit and land on Mars. Jet Propulsion Laboratory, the other major unit carrying out lunar and planetary exploration programs (Ranger, Surveyor, Mariner), also was playing a key role in Viking.
[323] American exploration of the Moon obtained space-proved systems to conduct specific observations and to gather precise data on the lunar environment, with or without men. But altering national priorities, government belt-tightening, and reduced NASA budgets foreclosed lunar exploration after the Apollo 17 landing in 1972, at least for this decade.
The once ambitious unmanned lunar exploration program, Surveyor Orbiter, which would have carried a wide variety of scientific instruments and experiments to the Moon's environment much as the Soviet Luna and Zond spacecraft have,³¹ has not been attempted again. Perhaps it was too ambitious for its time; and the road taken to land men on the Moon proved politically more reassuring.³² Certainly the five out of five successful missions of Lunar Orbiter and the desire to fly a sixth mission substantiated the philosophy within NASA that unmanned lunar probes served best when their objectives were simple, limited, and mutually supportive of each other and of manned exploration.
Had the Office of Space Science and Applications directed the five missions of Lunar Orbiter to conduct scientific [324] investigations of the Moon, independently of Apollo, then most likely the missions would have been different. Mission IV might have been the first to fly. A total survey of the Moon would have allowed scientists to select the most interesting sites for closer, more detailed photographic investigations. Surveyor spacecraft might have landed elsewhere than they did, because of Lunar Orbiter data; and even Apollo might have flown significantly different missions. This, however, did not happen.
If Lunar Orbiter had been totally independent of any manned exploration, much as the Mariner Mars spacecraft have been, then perhaps only part of the missions would have flown photographic payloads. Numerous experiments to analyze the Moon's environment existed or could have been designed to fly on an Orbiter, as they were flown on Explorer XXXV. Yet Lunar Orbiter could not have satisfied the poli-commitments the United States had made as a result of the early Soviet thrust into space. In fact, Lunar Orbiter was inseparably bound to the goals of the American manned lunar exploration effort.
The bond between Lunar Orbiter and Apollo fostered cooperation between the Office of Space Science and Applications and the Office of Manned Space Flight, which otherwise might have developed more slowly and less affirmatively. This cooperation brought about a higher. level of integrated activities among NASA centers far sooner than might have occurred [325] under different circumstances. The problems encountered in the Ranger and Surveyor Programs early in the sixties forced NASA Headquarters to search for other means of accomplishing the tasks of space exploration, leading it to delegate to the Langley Research Center a new area of responsibilities beyond its traditional role in research and development. In turn this move has broadened the agency's base for accomplishing ever more complex and sophisticated objectives in American space exploration.
It would be unjust, however, to claim that without Lunar Orbiter photography, Apollo could never have flown so early or that America could not have landed on the Moon in 1969. Lunar Orbiter greatly illuminated Apollo's way, but it is highly conceivable that the Apollo Program could have flown one or more manned orbital photographic missions before planning a landing. No Orbiter data went into the design of the. Apollo spacecraft system; and, indeed, the missions of Apollo 8 and 10 demonstrated the orbital capabilities of the spacecraft. The main objective of these two missions was testing the systems and the mission design short of actual landing on the Moon. The photography by the astronauts on these missions was concentrated on landing sites. The Lunar Orbiter photography covered almost the entire Moon and captured scenes of the lunar landscape under predetermined lighting conditions and at altitudes that [326] allowed Lunar Orbiter Program officials to obtain precise information about the landing sites, which the Apollo Program had requested. Moreover, it obtained these data at a time when they proved most useful to Apollo mission design.
Thus Lunar Orbiter saved Apollo time. It also saved money; the cost of one Apollo manned mission to the Moon was far higher than the total cost of the whole Lunar Orbiter Program. Without Lunar Orbiter, NASA might have had to fly one or more manned orbital missions around the Moon to photograph potential landing sites before an actual manned landing mission. Lunar Orbiter also gave Apollo flight operations personnel experience in tracking five spacecraft in orbit around the Moon. It provided valuable data on the lunar gravitational environment and its effects on orbiting spacecraft. It aided the Surveyor Program in selecting landing sites and then it photographed the landed Surveyors. Lunar Orbiter V photography of the crater Tycho and its vicinity proved instrumental in the decision to land Surveyor VIII north of Tycho in an area of high scientific interest but with topography greatly reducing the chances of a soft landing. Surveyor VII landed successfully and provided valuable data on an area of the Moon where astronauts did not land. The teamwork of the Lunar Orbiter V and Surveyor VII missions demonstrated the value of unmanned lunar exploration.
[327] The successful achievements of Lunar Orbiter and Surveyor also had far-reaching implications for planetary exploration. The former director of the OSSA Office of Lunar and Planetary Programs, Oran W. Nicks (later Deputy Director of the Langley Research Center), outlined some of these implications in an address to the American Institute of Aeronautics and Astronautics on December 5, 1968. He stated that experience gained in the initial stages of unmanned lunar exploration would have direct applications in the exploration of the planet Mars in the seventies.³³
Exploration of Mars at close range began in 1965 with the fly-by of Mariner IV. It provided man his first detailed glimpse of the Martian surface; surprisingly its pictures revealed many craters, showing apparent similarities to the Moon. In July and August 1969, Mariner VI and Mariner VII brought even closer views of the red planet when they flew by, taking pictures and measurements of the atmosphere and surface temperatures. Mariner IX went into orbit of Mars in November 1971 and in one year of observations changed scientists' views of the planet's weather and possible evolution. These spacecraft have opened many more areas of questioning than they have answered and, as a result, the Viking Program would search for evidence of life [328] on Mars during 1976-1977. Although the weight and payloads of the Viking Mars probes were to be substantially different from those of Lunar Orbiter, the spacecraft would profit from the Orbiter experience. The Viking Program at Langley and at JPL could use the knowledge gained from both Lunar Orbiter and Surveyor, although its goals required much more complex hardware and missions.
The Viking Program's relationship to Lunar Orbiter demonstrates how the Office of Space Science and Applications successfully built on the cumulative knowledge gained in its programs in the previous fifteen years. Among other achievements, this work proved the Orbiter concept and the feasibility of landing an unmanned spacecraft on another celestial body. Viking could draw on an an increasing treasury of proved concepts in furthering the unmanned exploration of the solar system. It also would add to that treasury. Nicks summed up the meaning of this work in his address to the American Institute of Aeronautics and Astronautics in December 1968:: Burning questions of immediate concern to you and me will be addressed by use of our new tools: "Is there life elsewhere? Has life existed on nearby planets and disappeared for any reason? Can nearby planets be made suitable for life?"; Together, orbiters and landers form a powerful team for the study of Mars and for seeking answers to these questions. Together, they will continue to extend our capabilities in what is probably the most challenging, open-ended arena for expansion of science and technology In the decade ahead.³⁴
[329] Men have now landed six times on the Moon and have returned with samples of its surface and subsurface materials. It still remains a mysterious body, its surface barely scratched; exploration of it has only begun. Mars, Venus, Mercury, and Jupiter have been studied by space probes and the other planets beckon men to pursue the quest for an answer to the origins of the Earth, the solar system, and, eventually, the universe.
Two Lunar Orbiter photographs had especially far-reaching implications for the Earth's population. The first was the Earth-Moon picture made in August 1966 by Lunar Orbiter I. Nearly half of the Earth was shown, as well as a substantial portion of the Moon's cratered surface.³⁵ The second was the Lunar Orbiter V picture of the nearly full Earth, taken in August 1967 while the spacecraft was at apolune in Its nearly polar orbit of the Moon.³⁶ Both were unscheduled pictures, requiring extra planning to execute. Their success proved the versatility of the Lunar Orbiter spacecraft and the skill of the flight operations personnel, bearing witness to America's technological Ingenuity and imagination.
[330] Yet both photographs were unrelated to the Apollo manned lunar landing missions. They came two years before the first landing. Although not the first pictures of the Earth from space, they were the first to show Earth at the distance of its nearest neighbor.
To the historian they have perhaps a different meaning than to the scientist. Men, it seems, have always been on one quest or another, using the Moon, the Sun, the planets and the stars in varying ways to explain their existence and their destiny. Half a millenium ago Europeans believed the Earth to be flat and the center of the universe. Then slowly men such as Copernicus, Kepler, Galileo, and Newton altered the thinking about the universe. The old Aristotelian-Ptolemaic concepts of physics and astronomy that had, in part, shaped medieval man's thinking about his existence, dissolved in the new body of increasing empirical data on man's natural environment. Yet only yesterday were men able to see how finitely microscopic their home in space is.
Man's technology has enabled him to escape the Earth, land on the Moon, and return. It also has silently, visually warned him that his only home, for the present, is the blue-brown-white gem around which the cratered, desolate Moon revolves.