|Where No Man Has Gone Before: A History of Apollo Lunar Exploration Missions|
LINKING SCIENCE TO MANNED SPACE FLIGHT
Manned Space Flight and Science
When the engineers of Robert R. Gilruth's Space Task Group began work on Project Mercury in 1958, they could not - as the space scientists could - draw on 10 years of experience in designing their spacecraft and conducting their missions. Aviation experience was helpful in some aspects of manned space flight, but in many others they faced new problems. Apollo posed many more. The engineers did not lack confidence that the President's goal could be met, but they knew only too well how much they had to learn to achieve it. A sense of urgency pervaded the manned space flight program from the beginning right up to the return of Apollo 11 - an urgency that determined priorities for engineers at the centers. Every ounce of effort went into rocket and spacecraft development and operations planning. Science was considerably farther down the list, and for the first five years they gave it little thought.
Manned space flight projects were ruled by constraints that were less important to science projects. One was safety. Space flight was a risky business, obviously, but the risks had to be minimized. No matter that the astronauts themselves (all experienced test pilots in the beginning, accustomed to taking risks) understood and accepted the risks. From the administrator down to the rank-and-file engineer, everyone knew that the loss of an astronaut's life could mean indefinite postponement of man's venture into space. Moreover, NASA was in a race, competing against a competent adversary and working in the public eye, where its failures as well as its successes were immediately and widely publicized.
Reliability was one key to safety, and spacecraft engineers strove for reliability by design and by testing. With few exceptions, critical systems - those that could endanger mission success or crew safety if they failed - were duplicated. If redundancy was not feasible, systems were built with the best available parts under strict quality control, and tested under simulated mission conditions to assure reliability.10 The measures taken to ensure reliability and safety contributed to the fact that manned spacecraft invariably tended to grow heavier as they matured, making weight control a continuing worry.
Those constraints were not so vital in the unmanned programs. Instruments needed no life-support systems and required no protection from reentry heat; scientific satellites were usually expendable. Being smaller than manned spacecraft, they required smaller and less expensive launch vehicles. Furthermore, those vehicles could be less reliable. More science could be produced for the money if experimenters would accept less than 100-percent success in launches, and space scientists were content with this.11 The loss of a scientific payload, though serious to the investigators whose instruments were aboard, did not cost a life.
On the whole the engineers were content to go their way while the scientists went theirs. But the scientists were not [see Chapter 1], and their protests seemed to require a response. Manned space flight enthusiasts spoke of the superiority of humans as scientific investigators and of the benefits to science that would result from putting trained crews in space or on the moon to make scientific observations. No existing instrument, they said, could approach a human's innate ability to react to unexpected observations and change a preplanned experimental program; if such an instrument could be built, it would be far more expensive than putting people into space.12
This argument did not move the space scientists, most of whom worked in disciplines where human senses were useless in gathering the primary scientific data. The role of a person in space science was not to make the observations but to conceive the experiment, design the instruments to carry it out, and interpret the results.13 Cleverness in these aspects of investigation was the mark of eminence in scientific research. The early manned programs offered space scientists no opportunities that could not be provided more cheaply by the unmanned programs. The relationship between the manned and unmanned programs - essentially one of independence - took quite a different turn with the Apollo decision. Within two weeks of President Kennedy's proposal to Congress, NASA Deputy Administrator Hugh L. Dryden told the Senate space committee that Apollo planners would have to draw heavily on the unmanned lunar programs for information about the lunar surface. Knowledge of lunar topography and the physical characteristics of the surface layer was vital to the design of a lunar landing craft. Ranger was the only active project that could obtain this information, and to provide it, NASA asked Congress for funds to support four additional Ranger missions. The day after Dryden testified, NASA Headquarters directed the Jet Propulsion Laboratory to examine how to reorient Ranger to satisfy Apollo's needs.14
This directive was received with mixed feelings by the participants in Ranger. JPL's project managers favored a narrower focus, because the scientific experiments were giving them technical headaches that threatened project schedules. They proposed to equip the four new Rangers with high-resolution television cameras and to leave off the science experiments, using the payload space to add systems that would improve the reliability of the spacecraft. Scientists who had experiments on the Ranger spacecraft, however, were upset by the proposed change. When they complained to Newell, he and his Lunar and Planetary Programs director reasserted the primacy of science in Ranger and did everything they could to keep the experiments on all the flights. But the difficulties with the Ranger hardware and the pressure of schedules proved too much. In the end, the problem-plagued Ranger carried no space science experiments on its successful flights, but did return photographs showing lunar craters and surface debris less than a meter* across.15
Apollo could command enough influence to affect the unmanned lunar programs, but science had no such leverage on manned flights. For that matter, scientists had little interest in Mercury; its cramped spacecraft and severe weight limits, plus the short duration of its flights, made it unattractive to most experimenters. Still, the Mercury astronauts conducted a few scientific exercises, mostly visual and photographic observations of astronomical phenomena.16 Comparatively unimportant in themselves, these experiments pointed up the need for close coordination between the scientists (and the Office of Space Sciences) and the manned space flight engineers. After John Glenn's first three-orbit flight on February 28, 1962, the Office of Space Sciences and the Office of Manned Space Flight began to look toward the moon and what humans should and could do there.17
Apollo managers had spent the second half of 1961 making the critical decisions about launch vehicle and spacecraft design; in the spring of 1962 they were wrestling with the question of mission mode. Should they plan to go directly from earth to the moon, landing the whole crew along with the return vehicle and all its fuel on the lunar surface? Or would it be better to assemble the lunar vehicle in earth orbit - which would require smaller launch vehicles but would entail closely spaced multiple launches, rendezvous of spacecraft and lunar rocket, and the unexplored problems of transferring fuel in zero gravity from earth-orbiting tankers to the lunar booster? Or was the third possible method, lunar-orbit rendezvous, preferable: building a separate landing craft to descend from lunar orbit to the moon, leaving the earth-return vehicle circling the moon to await their return?18 Apart from its essential impact on the booster rocket and spacecraft, the mission mode would determine how much scientific equipment could be landed on the moon, how many men would land to deploy and operate it, and how long they would be able to stay. Until the decision was made it was pointless to try to design equipment, but by early 1962 the mission planners needed to know in general terms what the scientists hoped to do on the moon and some important questions of responsibility and authority had to be settled.
* Ranger's results came too late (1964-1966) to affect the design of the Apollo lunar module; they did confirm that the designers' assumptions about the lunar surface were satisfactory and that the lunar module needed no modification.
10. For a discussion of some of the problems faced by the engineers in ensuring reliability, see Loyd S. Swenson, Jr., James M. Grimwood, and Charles C. Alexander, This New Ocean: A History of Project Mercury, NASA SP-4201 (Washington, 1966), pp. 167-213.
11. Newell, Beyond the Atmosphere, p. 163.
12. Scientists' Testimony on Space Goals, pp. 1 10, 244; Newell, "The Mission of Man in Space," address to Symposium on Protection Against Radiation Hazards in Space, Gatlinburg, Tenn., Nov. 5, 1962, text.
13. R. L. F. Boyd, "In Space: Instruments or Man?" International Science and Technology, May 1965, pp. 64-75. Boyd, a British astronomer with substantial experience in unmanned space science projects, presents the archetypal sky scientist's view - supremely confident of the potential of computerized systems and condescendingly contemptuous of the capability of man.
14. Hall, Lunar Impact, p. 114.
15. Ibid., pp. 289-96.
16. Swenson, Grimwood, and Alexander, This New Ocean, pp. 414-15.
17. Joseph F. Shea to Dir., Aerospace Medicine and Dir., Spacecraft & Flight Missions, "Selection and Training of Apollo Crew Members," Mar. 29, 1962.
18. Courtney G. Brooks, James M. Grimwood, and Loyd S. Swenson, Jr., Chariots for Apollo: A History of Manned Lunar Spacecraft, NASA SP-4205 (Washington, 1979), chap. 3.