The three astronauts would launch in the modified Apollo CSM on the Saturn IB rocket and then board the flyby spacecraft. They would use the RL-10 engines to guide the flyby craft to a docking with the S-IIB. The oxygen tankers would then dock in turn and pump their cargoes into the S-IIB's empty oxygen tank. Ruppe's flyby craft and booster would weigh 115 tons at Earth-orbit departure. The S-IIB would then ignite, burn to depletion, and detach, placing the flyby craft on course for Mars.
During the flight, the astronauts would regularly inspect and service the automated probes. As they approached Mars, the astronauts would release the probes and observe the planet using 1,000 pounds of scientific equipment. The flyby spacecraft would relay radio signals at a high data rate between the Mars probes and Earth until it passed out of range; then direct communication between Earth and the probes would commence at a reduced data rate.
As Earth grew large again outside the viewports, the flyby astronauts would enter the modified Apollo CSM and abandon the flyby craft. The CSM's propulsion system would slow it to Apollo lunar return speed, then the CM would separate from the SM, reenter, and land. Depending on the launch opportunity used, total mission duration would range from 661 to 691 days.
Even as Ruppe's report was published, the "robot caretaker" justification for piloted Mars flybys was becoming increasingly untenable. On 31 July 1964, the Ranger 7 Moon probe snapped 4,316 images of one corner of Mare Nubium before smashing into the lunar surface as planned. The images showed the Moon to be sufficiently smooth for Apollo landings, and gave the credibility of robot explorers a vital boost. As Ruppe published his report, Mariner 4, launched on 28 November 1964, was making its way toward Mars. Not long after Ruppe published his report, on 20 February 1965, Ranger 8 returned 7,137 images as it plunged toward the Sea of Tranquillity. A month later, Ranger 9 returned 5,148 breathtaking images of the complex 112-kilometer crater Alphonsus.
Beyond providing engineering and scientific justifications for the piloted flyby mission, Ruppe's report tendered a political justification. He wrote:
From the lunar landing in this decade to a possible planetary landing in the early or middle 1980s is 10 to 15 years. Without a major new undertaking, public support will decline. But by planning a manned planetary [flyby] mission in this period . . . the United States will stay in the game. 39
That Ruppe felt it necessary in early 1965 to attempt to justify a piloted Mars flyby mission in terms of probable impact on the U.S. domestic political environment is telling, as will be seen in the next chapter.
Chapter 4: A Hostile Environment
An era ended for the National Aeronautics and Space Administration last week when Congress voted a $234-million cut in that agency's budget authorization for Fiscal 1968 . . . . The NASA budget cut is symptomatic of the many currents of basic change that are flowing through the land this summer . ... If top NASA officials have not interpreted their admittedly long and arduous buffeting on Capitol Hill this spring and summer correctly, then they are facing a much worse time in the years ahead . ... (Robert Hotz, 1967) 1
Mariner 4
On 15 July 1965, the Mariner 4 probe snapped 21 blurry pictures of Mars' southern hemisphere as it flew by at a distance of 9,600 kilometers. The flyby, which marked the culmination of a seven-and-a-half-month voyage, was an unprecedented engineering achievement. Mariner 4 had withstood the interplanetary environment for nearly twice as long as Mariner 2 had during its 1962 Venus flyby mission.
Mariner 4 revealed Mars to be a disappointingly Moon-like, cratered world with no obvious signs of water. Scientists had expected to see a world more like Earth, where erosion makes obvious craters the exception rather than the rule. That Mariner 4's images were black and white accentuated the resemblance to Earth's desolate satellite. Canals were conspicuously absent. They are now believed to have been an optical illusion or a product of eyestrain.
Mariner 4's impact on Mars exploration planning is hard to overestimate. First, it showed that Maxime Faget had been right in 1962. Robots could perform Mars flybys—astronauts were not required for this particular exploration mission. It also showed that robot probes could reach Mars in reasonably good condition, undermining the "robot caretaker" justification for piloted Mars flybys.
Mariner 4's radio-occultation experiment revealed Mars' atmosphere to be less than 1 percent as dense as Earth's. Based on these new data and on measurements of the Martian atmosphere made from Earth since the 1940s, planetary scientists calculated that the majority of Mars' atmosphere was carbon dioxide, not nitrogen, as had been widely supposed. 2
The new Mars atmosphere data relegated to the recycle bin aerodynamic landing systems such as von Braun's delta-winged gliders and Aeronutronic's lifting-body. That meant more rocket propulsion would be required to accomplish a Mars soft landing, which would in turn demand more propellant. This would boost minimum lander weight, which meant more propellant would be needed to transport the lander from Earth to Mars. This in turn would boost Mars spacecraft weight at Earth-orbit departure, which meant, of course, that more expensive rockets would be required to launch the Mars ship into Earth orbit.
Most importantly, Mariner 4 dealt a body blow to hopes for advanced Martian life. Historically, human perceptions of life on Mars have occurred along a continuum. At one end stood the romantic view of nineteenth-century American astronomer Percival Lowell, whose Mars was a dying Earth inhabited by a race of civil engineers who had dug a planet-girdling network of irrigation canals to stave off the encroaching red desert. By the 1930s, Lowell's vision was widely seen as optimistic. Nonetheless, the romance of Lowell's Mars inspired would-be Mars explorers into the 1960s. 3
The Mariner 4 results eradicated any lingering traces of Lowellian romance, and in fact shifted the prevailing view of life on Mars all the way down the continuum to a pessimism with almost as little basis as Lowell's optimism. The spacecraft had, after all, imaged only 1 percent of Mars at resolution so low that, had it photographed Earth, scientists examining its pictures would likely have missed all signs of terrestrial life. 4 NASA took pains to point out that Mariner 4 had been intended only as a first, preliminary step toward resolving the question of life on Mars, and that it had "blazed the way for later spacecraft to land instruments and, eventually, men on Mars." 5
On the plus side, Mariner 4 provided the first firm data on conditions astronauts could expect to encounter in interplanetary space during the voyage to Mars. The intrepid robot registered fewer meteoroid impacts than expected, but also detected a higher-than-expected level of cosmic radiation and between 12 and 20 solar flares during what was expected to be a quiet Sun period. 6
Vietnam and Watts
President Lyndon Johnson supported the lunar program launched by his predecessor, which was not surprising, given that he had played a key role in formulating the Moon goal as Kennedy's Vice President and National Space Council chair. Like many others, however, he was uncertain what NASA's scope and direction should be in the years after it put an astronaut on the Moon. In a letter on 30 January 1964, Johnson asked NASA Administrator James Webb for a list of possible future NASA goals. 7
As stated in the last chapter, the outline of agency plans submitted to Johnson's Budget Bureau in November 1964 emphasized using Apollo hardware in Earth orbit. An Apollo-based piloted program in the early 1970s was seen as an interim step to an Earth-orbiting space station in the mid- to late-1970s. 8 When the National Academy of Sciences Space Science Board called instead for an emphasis on planetary exploration, NASA officials insisted that the Earth-orbital focus was President Johnson's preference. 9
This philosophy—that the United States would be best served by using Apollo hardware as an interim step to a future space station—set the tone for much of NASA's post-Apollo planning through the beginning of 1969. NASA's program for reapplying Apollo hardware was the Apollo Applications Program (AAP), an initially ambitious slate of lunar and Earth-orbital missions that eventually shrank to become the Skylab program. As shown in the last chapter, Mars planners in the Future Projects Office at Marshall sought also to apply Apollo technology to Mars exploration.
An event on 25 January 1965 also helped set the tone for NASA's post-Apollo future. On that date, President Johnson sent to Congress a $5.26-billion NASA budget for FY 1966, an increase of only $10 million over the $5.25-billion FY 1965 budget. This was the smallest NASA budget increase since the agency was established in 1958. NASA's eventual FY 1966 appropriation was $5.18 billion, the Agency's first budget drop. Most of the cuts came from AAP and other new starts.
This new frugality in the administration and in Congress with regards to space reflected growing unease across the United States. In August 1964, following a naval incident in the Gulf of Tonkin off North Vietnam, Congress passed the Tonkin Resolution, which empowered President Johnson to take what steps he deemed necessary to thwart further communist aggression in Indochina. In February 1965, Vietcong guerrillas attacked the South Vietnamese military base at Pleiku, killing 8 Americans and wounding 126. In response, Johnson ordered the bombing of North Vietnam's base at Dong Hoi. On 8 March, the first U.S. combat troops—two battalions of marines—joined the 23,000 American advisors already in South Vietnam.
As Mariner 4 approached Mars in July, President Johnson announced that he would increase the number of soldiers in South Vietnam from 75,000 to 125,000. On 4 August, while Mariner 4's images were trickling back to Earth, Johnson asked Congress for an additional $1.7 billion to support the expanding war.
On 11 August, as Mars planners attempted to reconcile the thin atmosphere and craters revealed by Mariner 4 with their old plans for Mars, racial violence flared in the Watts ghetto of Los Angeles, California. Five nights of anarchy left 34 dead and caused $40 million in damage.
Planetary JAG
Against this backdrop of war, social unrest, and Mariner 4 results, NASA launched a two-prong assault on Mars. The first, the Voyager program, aimed at planetary exploration using automated orbiters and landers. The second was an internal piloted Mars flyby study involving several NASA centers.
As already indicated, planetary scientists had rejected the AAP space station emphasis in favor of planetary exploration, which, they felt, was being neglected in NASA's headlong rush to reach the Moon. In its report Space Research: Directions for the Future, released in January 1966, the National Academy of Sciences Space Science Board designated "the exploration of the near planets as the most rewarding goal on which to focus national attention for the 10 to 15 years following manned lunar landing." 10 In May 1966, the American Astronomical Society Symposium "The Search for Extraterrestrial Life" re-emphasized the importance of seeking life on Mars despite the Mariner 4 results. 11 These inputs helped build both Voyager and piloted flyby mission rationales.
Voyager, first proposed in 1960 at the Jet Propulsion Laboratory (JPL) in Pasadena, California, was envisioned as a follow-on program to the Mariner flyby series. The 1960s Voyager should not be confused with the twin Voyager flyby probes launched to the outer planets in 1977 and 1978. In the FY 1967 budget cycle, NASA had postponed proposing Voyager as a new start following assurances that it could get off to an aggressive start in FY 1968. The delay was partly a result of the Mariner 4 findings. New atmosphere data forced a re-design that drove the program's estimated cost beyond $2 billion. 12 Voyager was initially targeted for first launch in 1971, with a second mission in 1973, and other missions to follow.