Voyager: The Grand Tour
of Big Science
by Andrew J. Butrica
Of all the NASA missions, none has visited as many planets, rings, and satellites, nor has provided as many fresh insights into the outer planets, as Voyager, which was launched in 1977. On 19 May 1981, the National Aeronautic Association awarded its Collier Trophy to the "Voyager Mission Team, represented by its chief scientist Dr. Edward C. Stone, for the spectacular flyby of Saturn and the return of basic new knowledge of the solar system."1 The awarding of the Collier Trophy was a fitting tribute to the science carried out by the Voyager spacecraft, which also received twice, in 1980 and 1981, respectively, the Dr. Robert H. Goddard Memorial Trophy, an aerospace industry prize awarded annually since 1958 by the National Space Club to recognize achievement in astronautics, for the Voyager encounters with Jupiter and Saturn.2
Neither the Goddard nor the Collier Trophy recognized completely the science accomplished by Voyager, for after flying by Uranus (1986) and Neptune (1989), it left the solar system to explore interstellar space until around 2020, when the spacecraft will lack sufficient power to operate the scientific instruments on board and to return data to Earth. By then, the two Voyager spacecraft will have operated longer, and returned data from greater distances, than any previous probe.
Voyager is planetary exploration on a grand scale. First conceived as a "Grand Tour" of the solar system from Jupiter to Pluto, then scaled back to a more modest mission called Mariner Jupiter-Saturn until its incarnation on the eve of launch as Voyager, the mission has been, and will remain well into the future, NASA's biggest planetary expedition. The two Voyagers have explored more planets (four), have discovered more moons (22), and have returned more photographic images, than any other space flight.3 The original price tag of nearly a billion dollars made it the second most expensive planetary voyage, exceeded only by Viking, which landed on Mars in 1976. 4 Each Voyager spacecraft weighed more than any Surveyor or Ranger sent to the Moon and more than any Mariner or Pioneer probe (except for Pioneer Venus), though less than the combined weight of the Viking lander and orbiter.5
Its scientific, budgetary, and technological immensity makes Voyager archetypical big science. Born of what President Dwight D. Eisenhower called the military-industrial complex, and what historian Stuart Leslie more recently has called the military-industrial
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|The Voyager mission team, represented by Chief Scientist Dr. Edward C. Stone received the award in 1980, specifically for the spectacular fly-by of Saturn and the return of basic new knowledge of the solar system. This photo is a montage of images of the Saturnian system prepared from an assemblage of images taken by the Voyager spacecraft during its Saturn encounter in November 1980. (NASA photo no. 80-H-366).|
academic complex,6 big science quickly came to characterize the civilian enterprise to explore space, that is, what one might call the NASA-industrial-academic complex. Since its creation in 1958, the National Aeronautics and Space Administration has shaped American science to an extraordinary degree, namely by providing the financial and institutional aegis for the transformation of American planetary astronomy into big science, yet NASA's primary objective was (and whose budgetary bulk paid for) the designing, building, and launching of vessels for the exploration of the solar system.
Although the Voyager mission is inescapably an example of NASA big science, the actual scientific experiments were carried out by scientists employed by NASA Field Centers or by individual scientists who more appropriately fit the category of little science. The latter Voyager scientists worked individually or in small collaborative groups, often with graduate assistants, in university laboratories with relatively small budgets and limited laboratory equipment. In the case of Voyager, the management of decision making and the organization of scientists, just as much as the creation and utilization of monumental technology and mammoth technological networks, delineated big science.
Planetary astronomy has had a long existence as simultaneously both little science (astronomers working individually or in small groups) and big science (large expensive telescopes and observatories) that dates back to the sixteenth-century island observatory of Tycho Brahe. The number, sophistication, and expense of instruments have escalated over
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the centuries, particularly in the past 100 years. The interplanetary spacecraft has become the new observatory, carrying scientific instruments on trajectories independent of the Earth's course through space. Planetary astronomy's very dependence on instrument technology necessarily and inescapably has driven it in the direction of big science.
The Voyager mission, and NASA planetary missions in general, illustrate the amphibious life of planetary astronomy as both little science and big science. The Voyager project transformed geographically-dispersed individual scientists drawn from a spectrum of scientific disciplines and subdisciplines into members of a centralized, multidisciplinary big science team. As each Voyager spacecraft approached one of its target planets, the members of the mission's scientific teams arrived in Pasadena, the home of the Jet Propulsion Laboratory, to take up residence for the period of closest approach. The mission provided those scientists a set of instruments and a spacecraft observatory. Their role was not limited to using the spacecraft instruments, however; those scientists also played a critical role in shaping the mission even before it was funded principally through the Space Science Board and its summer studies. Conflict between the scientific community and the NASA Field Centers, in particular, served as the catalyst that brought about the demise of Voyager's predecessor, Grand Tour. This chapter examines the role of scientists in the shaping of Voyager before launch and their transformation into a big science project team through their participation in the Voyager mission, then considers the critical role of technology in the conduct and success of that mission's science, as well as the relationship between big science and little science and the role of technology in that relationship.
Voyager can be said to have begun in 1965 as Grand Tour, an extensive, if not grandiose, planetary mission planned in the midst of shrinking NASA and Federal budgets, at a time when NASA sought to define its mission in the post-Apollo era. The Apollo lunar program in 1965 was reaching its funding peak; NASA's annual overall budget declined from $5.2 billion in 1965 to slightly over $3 billion in 1972, 7 in response to social and political pressure on the Federal budget stemming largely from the Great Society programs and the Vietnam War, as well as the conservative fiscal policy of the Nixon administration.
In the summer of 1965, in order to define post-Apollo NASA missions, the National Academy of Sciences' Space Science Board 8 held a summer study of scientists at Woods Hole, Massachusetts. The scientists urged NASA to shift interest from the Moon to the planets, giving primary emphasis to Mars and Venus, more so than to the outer planets. As for the outer planets, the summer study recommended two directions: either reconnaissance flyby missions to each of the outer planets or an intensive study of Jupiter using orbiters and atmospheric entry probes.9 These two exploration strategies dominated discussions of outer planet exploration over the following years. The 1965 Woods Hole summer study thus demonstrated that the congeries of scientists who made up the planetary scientific community already had ideas about how NASA ought to set about exploring the outer planets.
Most members of the planetary science community preferred smaller, tested spacecraft flying short missions over large, expensive, complex and lengthy projects. They feared that the government might cancel their smaller projects in times of tight budgets in favor of a few expensive high-profile missions. Moreover, with small inexpensive spacecraft launched at relatively
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short intervals, scientists could more easily follow up on new discoveries than they could with one large complicated spacecraft that took many years of preparation. Major missions to a large degree tended to solidify research into a specific line of investigation for a long time. 10
Into the gelling consensus that emerged from the Woods Hole study came the idea for Grand Tour. The Grand Tour would take advantage of a once-every-175-year planetary alignment to send several spacecraft to all five of the outer planets, from Jupiter to Pluto. Launch windows were available relatively soon, between 1976 and 1980.11 Despite its subsequent reputation as an exorbitant expenditure of public funds, a pair of Grand Tour spacecraft actually would have been far more economical than the several individual probes to the outer planets proposed by scientists at Woods Hole in 1965. Grand Tour could reduce costs further by surveying the outer planets in less time-in eight to thirteen years, depending on the trajectory, compared to thirty years for a direct flight to Neptune alone-by employing a maneuver called gravity assist,12 in which the spacecraft exploited a planet's gravitational field to increase its velocity and alter its trajectory, thereby reducing both launch power requirements and flight time.13 Grand Tour thus was intrinsically a money-saving concept.
Appearing to save money was critical to selling a large-scale project,
even during the days of big NASA budgets, as illustrated by the recollection
of Donald P. Hearth, NASA Planetary Programs Office director, when he learned
about Grand Tour for the first time:14
You've got to remember selling a new start is a bitch. Even then-it's even worse today, but even then. It's almost as hard to sell a hundred million dollar project as it is a billion dollar project. And a hell of a lot more work to sell two $100-million projects than one $200-million project.
Before NASA Headquarters considered Grand Tour, though, the jet Propulsion Laboratory15 started promoting it, beginning with a December 1966 article penned by
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|This reconstruction of part of the northern hemisphere of Ganymede was made from pictures taken by Voyager at a range of 313,000 kilometers (194,000 miles). The scene is approximately 1,300 kilometers (806 miles) across. It shows part of a dark, densely cratered block which is bound on the south by lighter and less cratered, grooved terrain. The dark blocks are believed to be the oldest parts of Ganymede's surface. Numerous craters are visible, many with central Peaks. The large bright circular features have little relief and are probably the remnants of old, large craters that have been annealed by flow of the icy nearsurface materials. The closely spaced arcuate, linear features are probably analogous to similar features of Ganymede which surround a large impact basin. The linear features may indicate the former presence of a large impact basin to the southwest. (NASA photo no. 79-H-393).|
Homer Joe Stewart, head of JPL's advanced mission planning. In 1967, JPL used the project as a lure in its employee recruitment literature.16 In short, although other NASA Field Centers competed, especially the Ames Research Center, JPL put forth a tremendous effort to make Grand Tour a JPL project.
The NASA Office of Space Science and Applications faced the task of establishing priorities among the various proposed missions to the outer planets. The agency called on its own scientific community to formulate outer planet exploration approaches and created the Outer Planets Working Group in 1969. Its creation was part of a larger agency reorganization initiated by Homer Newell, NASA associate administrator, in order to focus
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on the development of long-range plans, as opposed to the emphasis in preceding years on the budget year or on near-term plans. The reorganization resulted in the creation of twelve planning panels and six special study groups covering the gamut of NASA activities, with a Planning Steering Group chaired and coordinated by Newell himself. 17
The Outer Planets Working Group consisted of two representatives (a scientist and an advanced mission planner) from each of the NASA Field Centers interested in Grand Tour and other outer planet missions (JPL, Ames, Goddard, and Marshall) and from the Illinois Institute of Technology Research Institute's Astro Sciences Center, a NASA think tank of sorts which had initiated a Jupiter mission study in the fall of 1968. The Working Group thus limited the decision-making process to NASA Field Centers that were vying to design spacecraft; the external scientific community was not part of that process.
Rather than favoring a single Grand Tour to the outer planets, the Working Group endorsed the concept of multiplanet flyby missions, preferably two three-planet voyages (Jupiter-Saturn-Pluto in 1977 and Jupiter-Uranus-Neptune in 1979), on the grounds that these would reduce the mission time from thirteen or more years to only seven and a half.18 From June 1969, officials in the NASA Planetary Programs Office began to associate the phrase "Grand Tour" primarily with a pair of three-planet missions, rather than the original single tour concept.19
The Outer Planet Working Group also recommended that: "A new Mariner-class outer planets spacecraft appears adequate for accomplishing the more urgent scientific objectives."20 Although NASA ultimately followed that recommendation by building Mariner Jupiter-Saturn, the space agency did not heed the advice until Grand Tour's demise. One of the chief activities of the NASA Field Centers was the design and construction of spacecraft. Not surprisingly, then, the Working Group's advice also called for the designing and building of a large number of spacecraft.
NASA next put the question of outer planet exploration to the twenty-three scientists of the Space Science Board summer study that met in June 1969. Those scientists recommended a specific schedule of five outer planet missions: one to Jupiter, one to Jupiter and the Sun, one to Jupiter and Uranus, and the two Grand Tour missions outlined by the Outer Planets Working Group (Jupiter-Saturn-Pluto in 1977 and Jupiter-Uranus-Neptune in 1979). The recommendations artfully combined Jupiter-intensive exploration and separate missions to the transjovian planets, that is, what the scientific community originally set out at Woods Hole in 1965, with the Grand Tour notion issuing from NASA's jet Propulsion Laboratory. NASA headquarters planetary programs officials interpreted the findings of the 1969 summer studies as support from the scientific community for Grand Tour.21 NASA now intended to request Grand Tour funding for fiscal 1971.
Although the opinions of scientists and NASA Field Center experts had played the greatest role in shaping outer planet exploration up to this point, a new, and ultimately more powerful, player took the stage: the recently elected Nixon administration. The Bureau of Budget under Nixon consistently reduced NASA's budget allocation. No longer
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|This view of Jupiters ring was recorded by Voyager 2 on July 10, 1979, at a distance of 1.5 million kilometers (930,000 miles). The unexpected brightness is probably due to forward scattering of sunlight by small ring particles. Seen within the inner edge of the brighter ring is a fainter ring which may extend all the way down to Jupiter's cloud tops. The existence of the ring was first learned when photographed by Voyager 1 in March 1979. (NASA photo no. 79-H-507).|
was space exploration a tool for competing with the Soviet Union. Nixon perceived the Apollo program in partisan terms, as a Kennedy program. Thus, for example, in December 1969, the Nixon administration quickly moved to shut down the only NASA laboratory ever closed, the Electronics Research Center in Cambridge, Massachusetts, which Nixon was said to have perceived as a Kennedy pork project.22
The Nixon budget cuts hit NASA's fiscal 1971 budget, in which the space agency requested funding for two three-planet "mini" Grand Tours scheduled for launch in 1977 and 1979. At the same time, NASA faced the cost overruns of the Viking orbiter and lander, whose dramatically escalating overall cost was earning Viking the title of NASA's most costly project after Apollo (rising from $364.1 million in March to $606 million in August 1969). The Nixon administration cut NASA's budget, which translated into a loss of $75 million to the $413.9 million budget for NASA's Office of Space Science and Applications, the budget portion that fed Grand Tour. The "pain" of NASA's fiscal 1971 budget was not confined to Grand Tour, though, and included suspending production of Saturn V launch vehicles, stretching out Apollo lunar missions to six-month intervals, and delaying the launch of Viking from 1973 to 1975. 23 This first postponement of Grand Tour thus did not
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|"Gravity-Assist Swing-by Aids Many Missions" chart shows the swing-by as it deflects, accelerates, and decelerates. (NASA photo no. 69-H-1521).|
arise from any perception that the mission was too costly per se, but from a White House attempt to reduce NASA's, as well as the overall Federal, budget.
The severe and unprecedented reduction of NASA's Office of Space Science and Applications budget led Philip Handler, president of the National Academy of Sciences, to suggest to NASA administrator Thomas Paine in November 1969 that a Space Science Board panel evaluate and rank the disciplines supported by NASA, such as planetary and lunar exploration, astronomy, and Earth environmental sciences. Paine agreed. Subsequently, a summer study, involving nearly ninety scientists, took place at Woods Hole, Massachusetts, from July 26 to August 15, 1970. In addition, a fourteen-member executive committee, chaired by Space Science Board member Herbert Friedman of the Naval Research Laboratory, had the daunting task of combining the proposals of the working groups into an overall priority system.
What emerged was an ominous schism between the advice of the scientists of the Woods Hole Planetary Exploration Working Group and that of Friedman's executive committee. The Working Group urged that Grand Tour not be missed: it was a unique opportunity. The executive committee, on the other hand, favored Jupiter-intensive missions. The difference partly arose from concerns about the technological demands of the two types of missions. Jupiter-intensive missions required development of spacecraft lasting only five years; the real design challenge was in the probes, which had to withstand entry into the Jovian atmosphere. In contrast, while Grand Tour would not be entering any planetary atmospheres, it demanded spacecraft capable of enduring a much longer time period. In both
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cases, spacecraft design was intrinsically linked to mission cost. Even some Grand Tour advocates complained that JPL had not made any effort to design a more modest spacecraft with an estimated cost that would be more in line with the prevailing budgetary climate .24
The planetary scientists opposing Grand Tour fell into two camps. One camp preferred smaller, less costly, and shorter duration missions; the second feared that support of Grand Tour would divert funds from the building of a large space telescope. It was at this point that the perception that Grand Tour's price tag was too high emerged. Friedman led the contingent of astronomers who advocated building a large space telescope; they successfully placed the large space telescope in the highest priority category of the study. Friedman placed a higher priority on a large 45-inch orbiting telescope than on Grand Tour for reason of both its lower cost and its perceived higher scientific promise. Already, Grand Tour bore an estimated price tag of $700 million, and funding it, Friedman and others feared, would have a serious impact on other highly desirable scientific missions. The high cost of Grand Tour was being compared to Viking, which had become so costly that in early December 1969 an ad hoc Viking Review Panel set up by the Space Science Board almost recommended terminating the project.25 The collision of opposing views among scientists that the Woods Hole summer study brought to light was to resound throughout the space exploration community and to have an impact on Grand Tour. By December 1970, members of the Space Science Board were raising questions about Grand Tour. 26 Elsewhere, in negotiations with the Office of Management and Budget (OMB) in December 1970, George M. Low, NASA Acting Administrator, suggested replacing Grand Tour with a mission to Jupiter-Uranus-Neptune in 1979 and a possible additional mission to jupiter-Saturn-Pluto in 1977 or 1978, but which would require additional funding. 27
In January 1971, months before the publication of the Friedman report on March 9, 1971, Friedman's report was leaked to the House Subcommittee on NASA Oversight, as well as to the Washington press. John Lannan, a reporter for the Washington Evening Star, made public Friedman's anti-Grand Tour views, and a Science News article reported the opposing views of some of the Working Group members. The contention over the funding of Grand Tour now spilled over from the space and astronomical communities to the public at large and even beyond the nation's borders.28
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At the heart of the contention was the JPL Grand Tour spacecraft called TOPS. Grand Tour consisted of four launches, two to Jupiter-Saturn-Pluto in 1976 and 1977, and two to Jupiter-UranusNeptune in 1979. NASA estimated the cost of the four missions to range from $750 to 900 million plus $106 million for launch vehicles.29 One substantial portion of the cost of Grand Tour was development of a self-test and repair computer (STAR) that would operate for over ten years at a great distance from Earth. Another significant portion of the price tag represented development of the so-called Thermoelectric Outer Planets Spacecraft (TOPS) by JPL. The long lifetime of the TOPS spacecraft was to be achieved at the expense of increased vehicle weight and higher cost.30
Grand Tour TOPS and STAR development programs potentially represented a considerable fountain of paid employment for JPL employees, contractors, and subcontractors, as well as laboratory overhead, in the post-Apollo era. Contractor lobbying of the White House and Congress on behalf of the large space telescope helped to win congressional approval for it. Without that lobbying, historian Robert W. Smith has argued, Congress would not have approved funding the telescope.31 But ultimately the bid to develop TOPS reduced potential political support for Grand Tour's other options.32
Further complicating matters was Senator Clinton P. Anderson (D-NM), champion of the Los Alamos nuclear weapons laboratories and an enthusiast, until his retirement in 1973, of the development of a nuclear rocket engine called NERVA. As chair of both the Senate Aeronautical and Space Sciences Committee and the joint Atomic Energy Committee, Anderson provided NASA and the Atomic Energy Commission over $1.4 billion, about $500 million of which was spent in Los Alamos, for the development of the NERVA engine, which, Anderson held, was ideally suited for exploration of the outer planets, as well as for more advanced missions. Anderson worried that NASA and the OMB were shifting money from NERVA to fund Grand Tour. When the NASA budget came before Anderson's Aeronautical and Space Sciences Committee on May 12, 1971, his committee voted five to two to reduce Grand Tour's budget, while an amendment to increase NERVA funding passed. Werner von Braun worried that ardent congressional interest in NERVA would force a loss of Grand Tour in favor of a NERVA that had "no place to go."33
Meanwhile, NASA was trying to include Grand Tour as a new start in its 1972 fiscal budget. The Friedman report moved the Office of Management and Budget (OMB), in March 1971, to ask NASA to study simpler, less costly spacecraft alternatives to TOPS. The OMB also attempted to delay the Grand Tour start-up to fiscal 1973. 34
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OMB and congressional pressure to cancel TOPS and to cut NASA's budget, combined with the debate induced by the Friedman report, left NASA management in a quandary. In order to energize support for Grand Tour, and to answer general questions about outer planet exploration, NASA administrators again turned to the scientific community at a Space Science Board summer study held at Woods Hole, August 8-14, 1971. Unlike previous summer studies, this one concerned itself solely with outer planet exploration.
This latest summer study concluded that both Grand Tour (four TOPS probes) and the intensive study of both Jupiter and Saturn ought to be supported. Although the summer study scientists supported Grand Tour by a vote of 12-1, they cautioned that if NASA funding levels fell too low, Grand Tour ought to be abandoned in favor of a Mariner spacecraft mission to Jupiter and Saturn.35 The Mariner proposal was a return to the original 1965 Woods Hole idea of exploring the outer planets in piecemeal fashion.
As NASA prepared its fiscal 1973 budget, rumors spread that the "budget pinch" was going to affect planetary programs deeply and that the reduction of the Grand Tour payload from 205 to 130 pounds was "a likely fact of life."36 Furthermore, Grand Tour now began to compete for funding with the latest NASA human program: the Space Shuttle. The fiscal 1973 budget request NASA submitted to the OMB on September 30, 1971 included both Grand Tour and the Space Shuttle. Throughout the autumn of 1971, several press reports presciently reported Grand Tour's vulnerability to a possible elimination or reduction .37 On December 11, 1971, James Fletcher, NASA administrator since April 27, 1971, learned from White House officials that Nixon was prepared to approve the, shuttle program and that Nixon would not let NASA simultaneously fund the shuttle and the full TOPS Grand Tour in the 1973 budget or in subsequent fiscal years.38 Fletcher had to decide which was more important: Grand Tour or human flight.
By December 16, 1971, Fletcher had agreed to delete the TOPS version of Grand Tour from its fiscal 1973 budget request and to replace it with a pair of less expensive Mariner spacecraft to be known as Mariner Jupiter-Saturn to be launched in 1977. 39 The decision to kill Grand Tour was not made public immediately, and it was terrible Christmas Eve news at JPL. 40 Nixon, in his budget message of January 5, 1972, announced the development of the Space Shuttle, as well as the demise of TOPS Grand Tour and the substitution of the more modest Mariner Jupiter-Saturn mission.
Who killed Grand Tour? The demise of Grand Tour was less a simple case of its expensive price tag than its competition with other high-cost new starts (the shuttle and the space telescope) and Viking in a shrinking Federal and NASA budget. The smaller the budget became, and the more that costly programs competed for those shrinking funds,
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the more expensive each program appeared. To some extent, too, Grand Tour was a victim of the NASA preference for human space flight over scientific probes. The Space Shuttle was essential to continuing the U.S. human space flight program as Apollo wound down. The schism between how the planetary scientific community defined outer planet exploration —small, piecemeal ventures— and how JPL defined outer planet explorationa large, expensive project to exploit a rare planetary alignment, and the public airing of that schism, certainly contributed to the pressure on NASA administrator James Fletcher to cancel Grand Tour. Thus, at NASA's fiscal 1973 budget briefing on January 22, 1972, NASA administrator Fletcher explained that Grand Tour was eliminated because of a "less than enthusiastic response from certain elements of the scientific community particularly, and to some extent, Congress."41
But was Grand Tour really dead? Even before the public announcement of Grand Tour's demise, planning had begun for Mariner Jupiter-Saturn, the reduced-cost, twoplanet alternative to Grand Tour recommended by the most recent Woods Hole summer study. In December 1971, when NASA and the OMB agreed to delete fiscal 1973 funds for the TOPS Grand Tour, NASA informed the OMB that the JPL TOPS development group would be "retained and redirected into planning a new program to explore Jupiter and possibly Saturn with a three-axis stabilized Mariner-class spacecraft."42 (Stabilization along three axes was a requisite for onboard cameras.)
NASA administrators next turned to the scientific community in the guise of the Space Science Board. The Board met February 8-9, 1972, and "unanimously and warmly endorsed" Mariner JupiterSaturn. The Space Science Board, through its chair Charles H. Townes, expressed the hope that the spacecraft would remain operational beyond Saturn "and return very significant data on cosmic particles and fields."43
Congress greeted with approval the replacement of the TOPS Grand Tour with Mariner JupiterSaturn and authorized funds for Mariner Jupiter-Saturn for fiscal 1973. The Mariner Jupiter-Saturn price tag, $360 million versus $1 billion for TOPS Grand Tour, could fit into a scaled back NASA budget that also financed development of the Space Shuttle. Although work on Mariner JupiterSaturn started at JPL as early as January 1972, the new project was not officially approved by NASA until the Contractual Task Order was signed on May 18, 1972. 44
In order to reduce costs and overheads, NASA decided to leave design and construction of the Mariner Jupiter-Saturn spacecraft to JPL, rather than to Boeing, General Electric, Hughes, Martin Marietta, and North American Rockwell, all of which had some level of preparation for a Grand Tour proposal. The largest aerospace firms lobbied NASA Headquarters and Congress for the contracts. In order for expensive projects to pass congressional scrutiny as part of the NASA budget, they often had to include an intention to contract out much of the work. Thus, for example, Magellan, the radar imaging mission to Venus, although initially intended as a JPL in-house project for cost reasons, was let out to Martin Marietta (spacecraft contract) and Hughes (the radar contract).45 The decision to go with JPL versus an industrial contractor was viewed at NASA Headquarters by John E. Naugle, Associate Administrator for Space Science, as a "many faceted problem" whose
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resolution was "of paramount importance to the future of NASA's Planetary Program as well as to the future of JPL." In short, JPL needed the contract to maintain employment levels in the laboratory, and NASA Headquarters needed it to maintain the vitality of its planetary program. Therefore, he explained, "all of the various factors must be given careful and thoughtful consideration."46
Despite the limited aim of the Mariner Jupiter-Saturn, the mission had the Grand Tour launch window, that rare planetary alignment, and the engineers at JPL still had every intention of building a spacecraft that would last long enough to visit Uranus and Neptune. This intention was not emphasized; however, it was stated that a Mariner Jupiter-Saturn spacecraft might continue to Uranus if its mission at Saturn proved successful. The scientists working on the project knew that Mariner Jupiter-Saturn was going to go to Uranus and Neptune, too. As Bradford Smith, Leader of the Imaging Team, explained: "We understood at the time the enormous potential of this mission —that it could very well be one of the truly outstanding if not the most outstanding mission in the whole planetary exploration program."47
Grand Tour would rise from its own "death" as piecemeal additions to Mariner JupiterSaturn. As S. Ichtiaque Rasool, Deputy Director of Planetary Programs, Office of Space Science, reflected: "The lesson to be learned from Grand Tour cancellation was that you never fund such a big, long-term project at once. So we kept on adding piecemeal. And it's interesting that they always come out big. When you have less money, you can even do better sometimes."48 The Mariner design and experience were used whenever possible and were supplemented with subsystems designed for the Viking orbiter to provide the required performance and reliability. NASA instructed the Atomic Energy Commission to upgrade the plutonium batteries so they might last more than ten years, enough time for Mariner Jupiter-Saturn to encounter Uranus and Neptune.49 Despite the reliance on extant technology, some money was set aside to develop new technology. Congress and the OMB approved an additional $7 million to the Mariner Jupiter-Saturn appropriation for scientific and technological enhancements. Part of that appropriation went to develop a reprogrammable onboard computer,50 which proved vital to maintaining Voyager 2 as a functioning observatory in space. Without properly functioning hardware, no science could be conducted.
just as scientists played a key role in shaping Voyager before it was funded, they collaborated actively with NASA in defining the mission's scientific objectives within organizational
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frameworks established by NASA. On October 15, 1971, although Grand Tour had not yet been authorized, the space agency issued an "Invitation for Participation in Mission Definition for Grand Tour Missions to the Outer Solar System" to specify its scientific objectives, that is, typical payloads and scientific instruments requiring a long lead-time to develop. Among those primary objectives of Grand Tour (and Mariner Jupiter-Saturn) were: 1. physical properties, dynamics, and compositions of atmospheres; 2. geological features; 3. thermal regimes and energy balances; 4. charged particles and electromagnetic environments; 5. periods of rotation, radii, figures, and other body properties; and 6. gravitational fields. While travelling between planets, both missions would study variations of the solar wind plasma and magnetic field, solar energetic particles, galactic cosmic rays, and interplanetary dust. Once the spacecraft left the solar system, they could make measurements of galactic cosmic rays unmodulated by the solar plasma.51
Regardless of which objectives or instruments the scientific community recommended, JPL insisted on including video cameras. At JPL, Harris M. "Bud" Schurmeier, JPL's Grand Tour and Mariner Jupiter-Saturn project manager, understood both the non-scientific and the scientific importance of imaging the planets and their satellites. In 1964, Ranger lunar-impact probes radioed back the first close-up pictures of the Moon, thanks to hardware designed at JPL under his guidance. Subsequently, in 1969, Schurmeier led the work on Mariners 6 and 7 that achieved a hundredfold gain over tiny Mariner 4 in the return of pictures from Mars, and in 1971, Mariner 9 pictures of Mars, after waiting out a gargantuan dust storm. In addition to the imaging team, Mariner Jupiter-Saturn would have a Radio Science Team to exploit the scientific use of the spacecraft's radio systems.52 In selecting members of the scientific teams, the first members chosen were those of the imaging and radio science teams, the teams using the video and radio equipment that JPL intended to put on board, regardless of whatever scientific instruments might be selected.53 As the NASA Field Center in charge of the mission, JPL thus could exert a determining influence on the science to be conducted.
NASA, in April 1972, extended a formal request for experiment proposals and received over 200 replies. From those the space agency selected ninety scientists, mainly from the United States, but from France, Sweden, West Germany, and Great Britain, as well.54 The selection process favored researchers in large institutional settings, but did not filter out little scientists entirely. NASA policy was to select scientists based on the merit of their research, as well as the "reputation and interest of the institution." The stated reason for this selection standard was to insure "scientific depth and breadth, and the availability of the resources to support the investigation." NASA assumed that selected scientists would be affiliated with an accredited academic institution, a private corporation with sufficient contractual resources to provide the required scientific, technical, and
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administrative resources and support" (e.g., TRW or The Rand Corporation), or a NASA or other government center or laboratory. 55
Illustrating how the scientist selection process favored those in large institutional settings, such as NASA Field Centers, was the dominance of NASA's Goddard Space Flight Center scientists on the infrared spectroscopy and radiometry and the magnetic fields science teams. Eight of the eleven members of the first team were from Goddard, while seven investigators, only one of which came from outside Goddard (a German researcher) constituted the magnetic fields team .56
University planetary scientists populated most of the other science teams, although those scientists often counted on NASA funding for their research. NASA grants to university funding and NASA's use of university scientists drew them into the larger scientific enterprise of the NASA-industrial-academic complex, thereby weaving little science into the fabric of large-scale, big-budget science .57 Such was the case of the radio science team, which was a mix of Stanford University and JPL researchers.
The Stanford investigators, Von R. Eshleman, Thomas A. Croft, and G. Leonard Tyler, came from that institution's Center for Radar Astronomy. Founded in 1962, initially in collaboration with SRI personnel, and underwritten by NASA, the Center for Radar Astronomy sought to conduct planetary atmospheric, ionospheric, and surface studies using the radio equipment ordinarily (and necessarily) included on each spacecraft, although special hardware often was developed to perform experiments. The Center was small, however, in terms of budget and personnel.58 The remaining science team members, John D. Anderson, Gunnar Fjedlbo (now Lindal), Gerald S. Levy, and Gordon E. Wood were all JPL staff engineers and scientists. Fjeldbo, moreover, previously had been with the Stanford Center for Radar Astronomy.59
Stiff competition, and at times personality conflicts, reigned among the scientists submitting proposals.60 Among other factors, the selection or rejection of instrument proposals hinged not as much on the qualifications of scientists or their research, but on the
266 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
trajectory of the spacecraft and the discoveries of earlier missions. The assessment of the dangers of the asteroids, Saturn's rings, and Jupiter's electromagnetic environment was placed on a firmer foundation by the results beamed back by Pioneer 10 and 11, launched in 1972 and 1973, respectively. Although the asteroid hazard appeared less threatening, Pioneer 10 encountered far more damaging radiation than had been expected. Pioneer 11 reached Jupiter a year later (December 1974), then went on to Saturn, where the spacecraft passed within 21,000 km of Saturn's cloud tops in September 1979 and certified the safety of the narrow zone between Saturn and its rings.61 These Pioneer 10 and 11 results led to the dropping and adding of Mariner Jupiter-Saturn science experiments.
Once Pioneer 10 discovered that the levels of radiation at Jupiter were a thousand times more intense then expected, NASA dropped an ultraviolet photopolarimeter experiment that had been selected on a provisional basis. In the place of that instrument, and at the urging of the concerned scientific community, S. Ichtiaque Rasool, NASA Office of Space Science, included on Mariner Jupiter-Saturn a plasma wave experiment which had been proposed but not selected until then.62 On the other hand, other science experiments were selected or excluded on the basis of cost and spacecraft parameters. When drawing up the final list of investigators and instruments in September 1973, NASA dropped the micrometeorites experiment because of its development risk and cost, as well as the difficulty of integrating it into the spacecraft design.63
Perhaps the most unusual Voyager scientific experiment was that with no real Principal Investigator and essentially with no NASA budget for instrument construction or data analysis; it was the recording entitled "Sounds of Earth." On the chance that Voyager might encounter intelligent extraterrestrial life, NASA approved placement of a phonograph record on each of the two Voyager spacecraft. Recorded on a 12-inch copper disk, "Sounds of Earth" ran for nearly two hours. Its contents, assembled by a group of prominent scientists and educators led by Carl Sagan, who had placed extraterrestrial plaque messages on Pioneers 10 and 11, consisted of greetings from Earth in 60 languages, samples of music from different cultures and eras, and natural sounds of surf, wind, thunder, birds, whales, and other animals, as well as 115 photographs and diagrams in analog form, depicting human beings, the solar system, DNA, and various fundamental concepts from mathematics, chemistry, geology, and biology, and greetings from President Jimmy Carter and the Secretary General of the United Nations.64
The Voyager instruments and scientists selected, NASA then organized the scientists into twelve (later reduced to eleven) science teams. Except for the imaging and radio science teams, for which the project furnished the instrumentation, the individual science groups were responsible for designing and building the instruments associated with their
FROM ENGINEERING SCIENCE TO BIG SCIENCE 267
investigation areas. The eleven investigation areas were: imaging, radio science, infrared and ultraviolet spectroscopy, magnetometry, charged particles, cosmic rays, photopolarimetry, planetary radio astronomy, plasma, and particulate matter. Specific scientific objectives included the study of the physical properties, surface features, periods of rotation, energy balances, and thermal regimes of the planets and moons and investigation of electromagnetic and gravitational fields throughout the mission. Items of special scientific interest included Jupiter's giant red spot and Saturn's rings and moons, lapatus, Titan, and Rhea.65
Each science team had a leader, called a principal investigator, though
the heads of the imaging and radio science groups were designated team
leaders. The design and construction of the scientific instruments were
the responsibility of the principal investigators, who either could have
them built in their own laboratory or could contract for their construction.
The team leaders and principal investigators formed the Science Steering
Group, which had overall responsibility for advising NASA in the area of
Mariner Jupiter-Saturn science. By the end of 1972, Ed Stone, a magnetospheric
physicist from California Institute of Technology who had started on Grand
Tour in 1970, during the preplanning stage, was appointed Project Scientist.66
The Project Scientist stood at the interface between scientific needs and
engineering and budgetary constraints, between the Science Steering Group
and NASA, the public, the scientific community, and the press. In Stone's
own words, the Project Scientist served "an impedance matching function
between the engineering requirements and constraints and the science requirements
and constraints to try to find a way to achieve the optimum match between
these two different sets of requirements and desirements."67
In short, the management of science and decision making were centralized
in the Project Scientist.
Management of science included assuring that scientists' instruments were built on time and within budget and that they fit spacecraft parameters, especially payload weight, power requirements, physical and functional interface conditions, exposure to radiation, and the telemetry budget, that is, the allocation of down-link data bits without which data did not return to Earth.68 The Project Scientist also was the ultimate arbiter in deciding which experiments and which observations would or would not be done. At times, the scientists lacked agreement on which observations to make, and the Project Scientist had to decide which of two equally good observations would be made. Rather than vote on the issue, Stone made the decision himself. "It turns out," Stone reflected, "that's a much more critical role than I had thought ahead of time, and that's because ultimately what science is all about is making discoveries. By deciding to make this observation rather than that one, you're effectively deciding that that group of scientists gets to make a discovery and this group doesn't."69
The most visible of the Project Scientist's activities as the interface between the Voyager scientists and NASA, the public, and the media was the press conference.
268 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
The press conference was a keystone activity of the Project Scientist in his role as mediator among Voyager scientists. Press conferences, not scientific publications or conferences, were the venues where discoveries were first announced. Dealing with the media and the scientific process of discovery was the Project Scientist's major concern during the week around each encounter. Every day, working with the scientists of each investigation group, the Project Scientist had to determine what had been discovered, which discoveries were ready for release, and how they would be released in the press conferences.
The announcement of discoveries almost as they occurred, as well as the very aggregation of scientists into working groups, raised the question of intellectual property fights and priority of discovery. Ordinarily, scientists would hold their own data as proprietary, not sharing with any other scientist, so as to assure priority of discovery. However, not sharing data, Stone believed, "would have inhibited the total development of the scientific program"70
The idea of everyone sharing findings came to Stone from the need to
communicate those findings to the media. He attended the press conference
of Pioneer 10 when it encountered Jupiter. Stone, who previously
had worked only on Earth orbiting missions, was impressed by the scene:
"Here was a room full of reporters wanting to know what the scientists
had discovered. I mean, to me that was incredible. Normally there just
isn't that interest in what you're doing as a scientist. And here they
were day after day saying, 'Tell us what you've discovered. Tell us what
you've discovered.' I realized that with Voyager we had both the opportunity
and the obligation to communicate what we were discovering. To help the
media tell the story. But we had to do it in a scientifically credible
way."71 Having all Voyager scientists
share their data made the scientists act less as individuals and more as
members of a group, as they would on a typical big science project. The
initial publication of results, too, followed this big science group approach.
All of the initial publications resulting from a given encounter were published
in the same issue of a given journal, such as Science, Nature,
Journal of Geophysical Research. All scientists, therefore,
published at the same time, but as a group, that is, one paper represented
the discoveries of an entire science team. There was no question of priority,
Stone explained, "everybody had equal priority, because everybody was there
at the same time."72
The Mariner Jupiter-Saturn mission name persisted until March 1977, only a few months before launch. Many within the project and within NASA felt that the Mariner Jupiter-Saturn spacecraft departed enough from the Mariner family that a new name would be appropriate. As early as 1971, William H. Pickering, director of JPL, had suggested the name Navigator for the spacecraft pair. 73 NASA organized a name competition to choose the new name, and the winning nomination, "Voyager," was approved on
Morabito, however, was not an outsider; on the contrary, she was part
of the JPL Voyager team, and her discovery was recounted in Science along
with the other Voyager science reports. Moreover, neither Morabito nor
anyone else outside the project "scooped" the Voyager science team. According
to Physics Abstracts, the first announcement of the discovery of volcanism
on Io was the IAU Circular of March 1979, issued by Torrence Johnson of
the JPL Voyager team. Morabito, S. P. Synnott, P. N. Kupferman, Stewart
A. Collins, "Discovery of Currently Active Extraterrestrial Volcanism,"
204 (June 1, 1979), 972; 1 Johnson, E. E. Becklin, C. O. Wynn-Williams,
C. B. Pickett, and J. S. Morgan, IAU Circular 3338, March 16, 1979.
73. John E. Naugle to William H. Pickering, May 3,1971, record no. 005148, NASA Historical Reference Collection.
FROM ENGINEERING SCIENCE TO BIG SCIENCE 269
March 4, 1977. The name change, however, coming so close to launch date, gave rise to a certain amount of confusion. References to Mariners 11 and 12 and even Voyagers 11 and 12 are a legacy of this last change of name. 74
Despite the name change, Voyager remained in many ways the Grand Tour concept, though certainly not the Grand Tour (TOPS) spacecraft. Voyager 2 was launched on August 20, 1977, followed by Voyager 1 on September 5, 1977. The decision to reverse the order of launch had to do with keeping open the possibility of carrying out the Grand Tour mission to Uranus, Neptune, and beyond. Voyager 2, if boosted by the maximum performance from the Titan-Centaur, could just barely catch the old Grand Tour trajectory and encounter Uranus. Two weeks later, Voyager 1 would leave on an easier and much faster trajectory, visiting Jupiter and Saturn only. Voyager 1 would arrive at Jupiter four months ahead of Voyager 2, then arrive at Saturn nine months earlier. Hence, the second spacecraft launched was Voyager 1, not Voyager 2. The two Voyagers would arrive at Saturn nine months apart, so that if Voyager 1 failed to achieve its Saturn objectives, for whatever reason, Voyager 2 still could be retargeted to achieve them, though at the expense of any subsequent Uranus or Neptune encounter.
The taking of such precautions was normal for a venture where a certain number of spacecraft hardware breakdowns, called "anomalies" by NASA, are considered to be normal. Most are minor and have no impact on the ability of the spacecraft to carry out its scientific mission, such as the glitch that occurred during the launch of Voyager 2. Nonetheless, these anomalies emphasize the critical role that technology plays in the gathering of scientific measurements from a space-based observatory. Without that technology, no science is possible. The performance of the Voyager science mission from the moment of launch is a lesson in the critical role played by technology in the conduct of big science.
One serious anomaly that actually did limit the amount of Voyager science conducted was that of the scan platform. On February 23, 1978, before Voyager 1 reached Jupiter, its scan platform became "stuck" during an azimuth scan. The platform turned on three axes in order to aim the cameras, spectrometers, and photopolarimeter in a scientifically useful direction. The platform jam thus threatened to compromise critical scientific observations. Luckily, command sequences transmitted to the spacecraft succeeded in moving the scan platform; the crisis subsided.75
As Voyager 2 began to leave Saturn, and most of the scientific observations had been made on the planet, its 220-pound scan platform became stuck. The spacecraft cameras were sending back images of black space. The heavy workload during encounter, combined with an ineffective lubricant, likely caused the trouble, as engineers demonstrated on Earth-bound duplicate equipment. To help alleviate the platform problem at Uranus, the spacecraft was rolled when possible to perform large azimuth changes. The scan platform was moved only for smaller changes, and then only at slower speeds.76
The scan platform jam at Saturn occurred after most of the scientific observations had been made. Nonetheless, some science was lost. Whether one considered that science critical depended on one's interests. Certain project scientists wanted to play down the situation, and this annoyed those scientists who suffered real losses. The loss of two images of the moon Enceladus at a resolution of 1.6 kin was perhaps not as great as the loss of the six
270 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
images of Tethys at 1.7 km, because the best pictures available of that moon had a resolution of no better than 5 km. The loss of coverage was serious in the case of both moons, however, for now neither of them could be measured all the way around with the precision that scientists would have liked, or mapped as comprehensively as the mission cartographers had expected. Other lost science included imaging the dark side of Saturn's rings, and non-imaging lost data included a further occultation experiment using the star Beta Tauri; infrared measurements of the ring material as it entered the planet's shadow; ultraviolet spectroscopy of ring material by observations of the Sun through the rings, as well as a field and particle maneuver. In the judgement of Ed Stone: "We were fortunate that the platform didn't stop a few hours earlier."77
The other major hardware failure was in the radio systems of Voyager 2. Voyager 2, which encountered more planets and moons than its double, seemed to suffer the greater number of serious hardware failures. No science was lost in this instance, although the potential was present, and an attempt to repair the situation raised the possibility of creating a spinoff ground facility for use in radio astronomy and ionospheric research.
In late November 1977, while the two Voyagers were still on route to Jupiter, one of Voyager 2's two duplicate radio transmitters began to degrade. It was switched to low-power mode to nurse it along. Something was wrong, but there was no way to know exactly what. Months later, in April 1978, the Voyager team discovered that Voyager 2's backup receiver had failed to detect signals sent from Earth because of a shorted capacitor. The primary radio receiver suddenly failed completely, as well. Voyager 2 was silent. Continuing to Uranus and Neptune was no longer possible, unless a way could be found to communicate with the backup receiver. Moreover, the failure of the Voyager 2 primary radio system had potential repercussions beyond the Voyager project. Its radio equipment was very similar to that on Pioneer Venus, which was launched the following month, in May 1978. 78
Normally, the radio receiver automatically compensated for the Doppler shift of signals transmitted from Earth. The changing velocity and direction of the spacecraft relative to Earth caused this Doppler shift. Without the ability to compensate for the Doppler shift, the Voyager 2 radio system could not detect any signals sent to it. The solution to Voyager 2's radio problems came from NASA Deep Space Network engineers. They prepared computer tapes that slowly varied the frequency of the radio signals transmitted from Earth in order to compensate for the expected Doppler shift. The Deep Space Network station outside Madrid transmitted the first test signals on April 13, 1978. Fifty-three minutes later, Voyager 2's acknowledgement returned. The trick worked. As a backup measure, in October 1978, Voyager 2's memory banks were loaded to the brim with commands that would provide
FROM ENGINEERING SCIENCE TO BIG SCIENCE 271
for a bare-minimum science encounter at both Jupiter and Saturn, should radio contact once again be lost. The same procedure was followed for subsequent encounters at Uranus and Neptune .79
The radio and scan platform breakdowns were not the only hardware failures that threatened or curtailed Voyager science. Some of the scientific instruments themselves experienced intermittent malfunctions and even complete breakdowns. The high radiation levels at Jupiter caused difficulties in transmitting commands, and the photopolarimeter instrument suffered radiation damage. Moreover, in November 1980, as Voyager 1 was leaving Saturn, its plasma instrument stopped transmitting usable data. A similar fault had disabled the instrument for three months earlier in the year, as well as back in February 1978. 80
In spite of the hardware problems that constantly threatened to diminish the mission's scientific returns, Voyager encountered Jupiter and Saturn, then continued on to Uranus and Neptune, following the Grand Tour route. Piece by piece, the Grand Tour itinerary came together. The continuation of Voyager to Uranus and beyond was made possible by reprogramming the onboard computers, creating new software, and building new ground facilities, new technologies and techniques without which the science could not be conducted. The expansion of Voyager into an even larger scientific enterprise also had spinoffs of value to the little science conducted on Earth. But first, funding the extension to Uranus had to be approved.
In 1975, the Space Science Board recommended a Mariner Jupiter-Uranus mission to be launched in November 1979, fly by Jupiter in April 1981, and proceed to Uranus arriving in mid-1985. Mariner Jupiter-Uranus was not the only mission under consideration by NASA. The space agency still was attempting to cobble together a program of exploration of the outer planets in the face of declining budgets. Other proposals included a Mariner Jupiter Orbiter (later developed into project Galileo) and Pioneer missions carrying atmospheric entry probes either directly to Saturn or to Uranus via Jupiter.81
Mariner Jupiter-Uranus was planned for NASA's fiscal 1977 budget and bore a price tag of $177 million, but it was in serious question because of the Administration's announced federal budget squeeze. In May 1975, NASA issued an announcement of opportunity for scientists to participate in Mariner Jupiter-Uranus.
An alternate solution to Voyager 2's radio problem considered
by NASA was to send commands through one of the science instruments, namely
the planetary radio astronomy receiver. Tests conducted during September
1978 using the Stanford radio telescope indicated less received signal
strength than had been anticipated, and the approach required both major
changes in the onboard computer programs and the construction of a suitable
ground transmitter facility. Implementation would cost an estimated $10
million ($7.5 million facility $2.5 million project) and would require
about twenty-four months to develop. Realizing that if the capability were
never used, NASA would be open to criticism for having built an unnecessary
facility, the Voyager Program Office decided against the planetary radio
astronomy solution. A. Gustaferro to Associate Administrator for Space
Science, February 1, 1980, and attachments, record no. 005566, NHO; Raymond
L. Heacock to Rodney A. Mills, 29 March 1979, record no. 005566, NASA Historical
Reference Collection; Von R. Eshleman, interview with author, Stanford
University, May 9, 1994, JPL Archives.
80. Rodney A. Mills, Voyager Program Manager, to Distribution, February 24,1978, record no. 005566, NASA Historical Reference Collection.
81. Burgess, Far Encounter, pp. 1 and 2; Davies, p. 39.
272 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
Facing budget restrictions, still, NASA Headquarters dropped the project from its fiscal 1977 budget request, causing a severe manpower problem at JPL. 82 Adding Uranus to the Voyager project, on the other hand, bore a price tag far less than that for Mariner Jupiter-Uranus, about $100 million over five years, and it would bring money to JPL. Approval of the mission extension was received in November 1980 and was based on Voyager 1 achieving adequate Titan and Saturn ring science and the health of Voyager 2. JPL had a long lead-time, five years, to prepare for Uranus: Voyager 2 would not reach Uranus until January 1986. 83
The extension of the mission to Uranus and beyond required re-engineering the spacecraft, which was already far from Earth, and upgrading Earth communication facilities. These changes were compelled by the vast distances over which the Deep Space Network had to communicate with Voyager, and by the dearth of sunlight needed for imaging and certain scientific experiments. The Sun at Uranus is only one fourth as bright as at Saturn and provides less than one four hundredths of its earthly illumination. Television exposures needed to be longer; camera shutter speeds reduced.
In upgrading the Mariner 10 camera to image Mercury, JPL engineers developed a new electronic technique that read out the image signal three times more slowly when desired. When the Voyager cameras were operated in this slow mode, the lower radio transmission rate was adequate for realtime communications from Saturn, because the video signals could still flow directly from the camera to the radio transmitter and on to an attentive Earth. While Voyager would use the same slow camera mode and transmission rates at Uranus, additional techniques, namely compression and improved encoding, were demanded.
Part of the $7 million of additional appropriation granted Mariner Jupiter-Saturn
in fiscal 1973 for technical improvements went toward design of an electronic
means for transmitting error-free data to Earth, what is known as Reed-Solomon
coding in honor of its inventors. Only basic coding hardware had been incorporated
into Voyager's computer when it was launched. For the Uranus encounter,
JPL engineers developed a special Reed-Solomon coding, which the Deep Space
Network transmitted to Voyager's computer. The improved encoding worked,
but it required more work on the ground.
Voyager engineers also used a technique called compression to obtain images from beyond Saturn. Normally, the full light-intensity value of each pixel of every image is transmitted back to Earth. Compression consists of sending back only the difference in light intensity between adjacent pixels on each line of each image. The technique reduced the communications rate needed by a factor of two and a half. But, in order to exploit compression, the spacecraft's computers had to be assigned new tasks, and that involved a certain risk. If a problem arose with the primary flight data computer, while the backup computer was tied up executing compression commands, key scientific observations, or even the entire mission, might be lost.84
Following the Grand Tour road to Uranus and Neptune also required revamping ground-based communication facilities. The distance to Uranus was over a billion kilometers. Signal strength was about one-fourth the level of the Saturn fly by in 1981, when Voyager was transmitting from a distance of 605 million kilometers. Existing ground-based Deep Space Network facilities were unable to adequately communicate with
FROM ENGINEERING SCIENCE TO BIG SCIENCE 273
Voyager at those great distances. The solution was to array antennas together, a technique commonly used in radio astronomy. At the Deep Space Network site outside Canberra, Australia, two 34-meter and one 64-meter dish antennas were arrayed together. In addition, through an international agreement, NASA linked its Deep Space Network Canberra dish antennas with the 210-foot Parkes radio astronomy telescope located 200 km away via a microwave connection. Of the three Deep Space Network locations, that in Australia would have the best view of Uranus during Voyager 2's ring plane crossing and closest encounter with the planet.85
A similar arrangement was put together at the Deep Space Network site at Goldstone, California, for the Voyager encounter with Neptune. Because Neptune is three times farther away from Earth than Saturn is, the Voyager X-band radio signal would be less than one-tenth as strong as during the Jupiter encounter in 1979 and less than one-half as strong as during the Uranus encounter in 1986. Part of the Voyager upgrade of the Goldstone 64-meter antenna involved enlarging the dish diameter 70 meters, increasing the surface accuracy, and improving the receiving system, as well as the installation of 34-meter antennas, to be used in an array formation, at the Goldstone and Canberra Deep Space Network sites.86
NASA approached the management of the Very Large Array (VLA), a radio telescope located in New Mexico, about participating in the formation of an antenna array with the Deep Space Network dishes at Goldstone, in order for NASA to communicate with Voyager at Neptune. The space agency installed low-noise X-band receivers on each of the 27 VLA antennas. Through the radio astronomy technique of arraying, and the installation of low-noise receivers on each VIA dish at NASA's expense, the echoes received from the VIA were combined with those received at the Goldstone 70meter and 34-meter dishes to provide a data rate more than double that which would have been available with Goldstone's antennas alone. Just as with the Parkes radio telescope, a microwave link permitted NASA to array the VIA and Deep Space Network dishes at Goldstone .87
The Voyager upgrade of the VLA inadvertently created a state-of-the-art facility for planetary radar astronomy, a scientific activity that was, and remains, little science in terms of manpower, instruments, budget, and publications, but which took root within the interstices of big science.88 When radar astronomers linked the Goldstone radar and the VLA in a bistatic mode, that is, with Goldstone transmitting and the VLA receiving, they created a radar with an extraordinary capacity for exploring the solar system. Duane O. Muhleman, California Institute of Technology, his graduate students Bryan Butler and Arie Grossman, and Martin A. Slade of JPL have used the GoldstoneVLA facility to explore Titan, Venus, Mars, and Mercury. Their exploration has led to a number of major discoveries, including the presence of polar ice on Mercury.89
274 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
As Voyager travelled from one planet to another, from one spectacular and unexpected discovery to the next, scientists and the public marvelled at the outcome of this scientific expedition. In the words of Project Scientist Ed Stone: "There's one lesson we learned from Voyager: Nature is much more inventive than our imaginations."90 The Voyager mission truly deserved the honor of the 1980 Collier Trophy. Moreover, its subsequent accomplishments beyond Saturn in the face of hardware and budgetary hindrances have merited further recognition.
The crucial role played by technology in the success of the Voyager scientific mission allows us to draw some conclusions about the nature of big science. Obviously, Voyager science was entirely dependent on the availability of the spacecraft and its assemblage of scientific instruments. Hardware failures threatened the loss of science. That science depended, too, on the availability and proper functioning of an extensive network of telecommunication facilities on Earth. A similar dependence on technology is found in ground-based planetary astronomy.
The technologically driven nature of Voyager science raises questions about the epistemology of space-based science. In an Earth observatory, an astronomer can look through the lenses of a telescope and see the object of study. Using a space-based observatory, such as the Voyager spacecraft, scientists do not experience nature as directly as through a telescope. Instead, a scientific instrument makes the observation, then electronic circuitry aboard the space-based observatory converts the observation into strings of digital bits and transmits those bits to Earth, where a Deep Space Network facility acquires them. Through various signal-processing stages, which require extensive manipulation by large computers, the strings of digital bits transmute into data, which scientists then study. It is this data that scientists study and from which they draw conclusions about the phenomena that interacted with the scientific instrument in space. Data, rather than direct observation, has become the object of research, and that change has required inclusion of certain assumptions about the relationship between phenomena and the data. Thus, the instrument of scientific research is no longer just the spectrometer or the telescope (to use an Earth-bound analogy), but the observatory and the totality of electronic operations (both telecommunications and computing) required to turn the observation of the instrument into data. Historians of science need to explore how computers, signal processing, and other electronic techniques have come to mediate between the observer and the observed and to determine to what extent this transformation has been precipitated by the advent and growth of big science. Clearly, though, it is large-scale technology and techniques that make possible the science.
The Voyager project was an example of big science as measured by a number of yardsticks, such as the number of planets, satellites, and rings studied, mission longevity, and cost. At the same time, little science was an integral part of the project. The creation of the Goldstone-VLA array to receive Voyager images from Neptune also furnished radar astronomy's little science with a facility. More directly, university based scientists became part of Voyager big science through their organization into science teams and through the centralization of science and other decision making in the Project Scientist. The literature holds additional examples of big science as the centralization and management of little science.
James Watson, former head of the Human Genome Initiative, claims the project utilized a "little science approach" partly because only its management, and not the work, was centralized. In her study of fusion, Joan Lisa Bromberg argues that centralizing the research decision-making process, rather than centralized facilities, defined the institutional boundaries of big science. James H. Capshew and Karen A. Rader, furthermore,
FROM ENGINEERING SCIENCE TO BIG SCIENCE 275
contend that activities that are broad in scope, scientific exploration being a specific example they cite, are big in the sense that they require coordination among geographically dispersed investigators or facilities. Consequently, the hallmark of such Big Science is horizontal integration and a reliance on extensive communication networks and centralized work processes.91 The history of Voyager shows that yet another example of big science as horizontal integration of science management is the organization of the geographically dispersed Voyager scientists into teams and the concentration of decision-making in a single individual, the Project Scientist.
Within the NASA-industrial-academic complex, little science and big science do not always dovetail. The discussions of outer planet exploration within Space Science Board summer studies leading up to the decision to terminate Grand Tour illustrate this point. Planetary scientists wanted Jupiter-intensive studies and separate missions to the individual outer planets, while NASA (especially JPL) wanted to send numerous spacecraft to the outer planets, but each one taking advantage of the rare Grand Tour launch window. The division between JPL and the planetary science community stemmed largely from their divergent interests. The primary activity of JPL and NASA was the designing, building, and launching of vessels for the (preferably manned) exploration of the solar system. The planetary science community, on the other hand, wanted to do science, rather than build spacecraft.
Despite this division, NASA and the planetary science community had much in common. As Joseph Tatarewicz has shown, NASA has transformed American ground-based planetary astronomy into big science through its financing of the scientific enterprise.92 By funding the construction and launching of spacecraft laden with scientific instruments, NASA also has positioned itself as the patron of space-based big science. NASA funding of both space-based and earth-bound planetary science is not the only way in which NASA has incorporated little science into big science. The organization of scientists into investigation areas and the centralization of the management of science into the Science Steering Group and the Project Scientist on the Voyager mission was another way in which NASA weaves little science into the larger fabric of big science.
This brief over-view of Voyager stressed the critical role of properly functioning technology in the success of the scientific mission. The dependence of science on instrumentation for observation and the need for science funding is at the core of the relationship between big science and little science. Critical, too, is the inescapable fact that planetary science is based on observation. Without the Voyager observatory and its payload of instruments, planetary scientists would have been without data, without observations. NASA funding also paid for the scientists to participate in the project. To what extent could planetary science be conducted without NASA and the trappings of big science?
And by any estimation the planetary science conducted by Voyager was
impressive. just a partial list would include the following, and fully
justify the recognition the mission has received:
276 VOYAGER: THE GRAND TOUR OF BIG SCIENCE
As big science became the dominant way of doing science in the latter half of the twentieth century, what we call little science has become a necessary and integral part of Big Science. In the case of Voyager, spinoff facilities, summer studies, and, above all, the organization of scientists into the Science Steering Group, integrated little science into the overall big science undertaking. Many Earth observatories continue the tradition of blending little and big science. Individual scientists from universities request time on a large telescope, usually funded by public money, in order to make observations. The scientist might have funding from the National Science Foundation or NASA. There is no longer a distinction between big science and little science, but a single scientific enterprise in which the two are woven together in a set of interdependent relationships, each part of the same fabric.