The NASA Headquarters Office of Manned Space Flight (OMSF) under George E. Mueller, Associate Administrator for Manned Space Flight, managed the piloted flyby study. Mueller had taken charge of the OMSF in September 1963 and had set up the Advanced Manned Missions Office under Edward Gray in November 1963 to direct NASA's piloted planetary mission planning activities. At a meeting on 15 April 1965, Mueller had received authority from NASA Deputy Administrator Robert Seamans to put together a NASA-wide group to plan piloted planetary missions. A preliminary meeting of the group occurred on 23 April 1965. This prepared the ground for development of the Planetary Joint Action Group (JAG), which was formally established later in the year. The Planetary JAG was headed by Gray and drew members from NASA Headquarters, Marshall, MSC, and Kennedy Space Center (KSC), as well as from the Apollo planning contractor, Bellcomm. 13
Initially the Planetary JAG's focus was on piloted Mars missions using nuclear rockets. In April 1966, however, Mueller launched a piloted Mars flyby study within the Planetary JAG at the request of Nobel Laureate Charles Townes, chair of the NASA Science and Technology Advisory Committee. Townes had asked Mueller in January 1966 to carry out a study comparing the unpiloted Voyager project with a piloted flyby with robot probes (what he called a "manned Voyager"). 14 In the second half of 1966, NASA spent $2.32 million on 12 piloted planetary mission studies supporting the Planetary JAG. 15
Figure 7—The 1966 Planetary Joint Action Group study used existing and near-term technology for its piloted Mars flyby spacecraft design. Note the Earth Entry Module (left) based on the Apollo Command Module. (NASA Photo S-66-11230)
Image
Later that year, Mueller testified to the House Space Committee on the benefits of a piloted flyby. He explained that it
afforded the best opportunity for performing manned planetary exploration with minimal cost and at an early date . . . . The attractiveness of this type of mission . . . stems from the relatively light burden which it imposes on the propulsion system, although the short interval of direct contact with the target planet detracts from its desirability. The usefulness of the flyby mission becomes clearly established when viewed as an in-situ test-bed for evaluating the performance of various subsystems such as navigation, life support, and communications to be used in later landing missions; [and] when also viewed as a platform for launching instrumented probes toward the target planet during the close passage. 16
On 3 October 1966, the Planetary JAG published its Phase 1 report, Planetary Exploration Utilizing a Manned Flight System. 17 The report placed piloted flybys within an evolutionary "integrated program" of new and Apollo-based technology with "balanced" use of humans and robots, the objective of which was "maximum return at minimum cost, assuming intensive investigation of the planets is a goal." By this time the integrated program concept had been discussed for more than a year outside NASA. 18 The Planetary JAG's integrated program proceeded through the following steps:
- Apollo Applications Program (1968-73): Astronauts would remain aloft in space stations based on Apollo hardware for progressively longer periods to collect data on human reactions to weightlessness. Some would live in Earth orbit for more than a year—approximately the duration of a piloted Mars flyby mission.
- Mariner (1969-73) and Voyager (1973): The Planetary JAG report cast Mariner and Voyager as lead-ins to piloted expeditions by stating that data they collected would aid engineers designing piloted flyby hardware. A Mariner probe would fly by Mars in 1969; in 1971 another Mariner would drop a probe into Mars' atmosphere. The first Voyager probe would land on Mars in 1973 bearing a suite of life-detection experiments.
- Piloted Mars/Venus Flybys (1975-80): The first piloted Mars flyby mission would leave Earth orbit in September 1975. Mars flyby launch opportunities would also occur in October 1977 and November 1979. Multiple flyby missions were possible—a Venus/Mars mission could start in December 1978, and a Venus/Mars/Venus mission could launch in February 1977. These would dispense automated probes based on Mariner and Voyager technology.
- Piloted Mars Landing and piloted Venus Capture (orbiter) missions (post-1980) would see introduction of AEC-NASA nuclear-thermal rockets. The Planetary JAG deemed nuclear propulsion "essential for a flexible Mars landing program" capable of reaching Mars in any launch opportunity regardless of the energy required. (The nuclear rocket program is described in more detail in Chapter 5.)
The Planetary JAG's piloted Mars flyby spacecraft would reach Earth orbit on an Improved Saturn V rocket with a modified S-IVB (MS-IVB) third stage. The MS-IVB would feature stretched tanks to increase propellant capacity and internal foam insulation to permit a 60-hour wait in Earth orbit before solar heating caused its liquid hydrogen fuel to turn to gas and escape.
The four-person flyby crew would ride into Earth orbit on a two-stage Improved Saturn V in an Apollo CSM stacked on top of the flyby craft. Upon reaching orbit, the CSM/flyby craft combination would detach from the spent Saturn V S-II second stage; then the astronauts would detach the CSM, turn it around, and dock with a temporary docking structure on the flyby craft's forward end.
The Planetary JAG's flyby spacecraft would consist of the Mid-Course Propulsion Module with four main engines; the Earth Entry Module, a modified Apollo CM for Earth atmosphere reentry at mission's end; and the Mission Module, the crew's living and working space. The Earth Entry Module would serve double duty as a radiation shelter during solar flares. Mid-Course Propulsion Module propellant tanks would be clustered around it to provide additional radiation shielding. The Mission Module's forward level (for "rest and privacy") would be lined with lockers containing freeze-dried foods; the aft level would contain the flyby craft's control console, science equipment, and wardroom table. The Planetary JAG report proposed that the Mission Module structure and subsystems, such as life support, be based on Earth-orbital space station module designs.
Figure 8—Typical piloted Mars flyby mission. 1—depart Earth orbit. 2, 4, 10—course corrections. 3, 5, 6, 7—eject automated Mars probes. 8—automated probe collects Mars surface sample and launches it off the planet. 9—piloted flyby craft retrieves Mars surface sample. 11—crew leaves Mars flyby craft in Earth return capsule. The abandoned flyby spacecraft sails past Earth into solar orbit. 12—Earth atmosphere reentry and landing. (Planetary Exploration Utilizing a Manned Flight System, Office of Manned Space Flight, NASA Headquarters, Washington, DC, October 3, 1966, p. 16.)
Image
With the crew and flyby craft in Earth orbit, three Improved Saturn V rockets would launch 12 hours apart to place the three MS-IVB rocket stages in orbit. This rapid launch rate, a veritable salvo of 3,000-ton rockets, each nearly 400 feet tall, would demand construction of a third Saturn V launch pad at KSC. The Planetary JAG determined, however, that Pad 39C would be the only major new ground facility needed to accomplish its flyby program.
Using the CSM's propulsion system, the astronauts would perform a series of rendezvous and docking maneuvers to bring together the flyby craft and three MS-IVBs. The flyby crew would then undock the CSM from the temporary docking structure, re-dock it to the airlock docking unit on the flyby craft's side, and enter the flyby craft for the first time. They would discard the CSM and eject the temporary docking structure.
Figure 9—Three modified Apollo S-IVB stages burn one after the other to launch the 1967 Planetary Joint Action Group Mars flyby spacecraft out of Earth orbit. (NASA Photo S-67-5998)
Image
Launch from Earth orbit would occur between 5 September and 3 October 1975. The MS-IVB stages would in turn ignite, deplete their propellants, and be discarded. As Earth and Moon shrank in the distance, the crew would deploy the radio antenna and rectangular solar array.
Figure 10—Following final S-IVB stage separation, the 1967 Planetary Joint Action Group's Mars flyby spacecraft deploys solar arrays and a dish-shaped radio antenna. (NASA Photo S-67-5991)
Image
The astronauts would perform a wide range of scientific experiments during the 130-day flight to Mars. These included solar studies, monitoring themselves to collect data on the physiological effects of weightlessness, planetary and stellar observations, and radio astronomy far from terrestrial radio interference.
Mars flyby would occur between 23 January and 4 February 1976, the precise date being dependent on the date of Earth departure. Beginning several weeks before flyby, the crew would turn the craft's telescope toward Mars and its moons. The pace would quicken 10 days before flyby, when the flyby craft was 2 million kilometers from Mars. At that time the astronauts would use the probe deployment arm to unstow and release the automated probes. At closest approach, the flyby spacecraft would fly within 200 kilometers of the Martian dawn terminator (the line between day and night).
Figure 11—The 1967 Planetary Joint Action Group's Mars flyby spacecraft releases automated probes and deploys instruments. Close Mars flyby would last mere hours, but the astronauts would study themselves throughout the mission, helping to pave the way for future Mars landing expeditions. (NASA Photo S-67-5999)
Image
For the 1975 mission, the flyby craft would carry in its Experiment Module three 100-pound Mars impactors, one five-ton Mars polar orbiter, one 1,290-pound Mars lander, and one six-ton Mars Surface Sample Return (MSSR) lander. The MSSR was designed to leave the flyby craft, land on Mars, gather a two-pound sample of dirt and rock, and then blast it back to the passing flyby craft using a three-stage liquid-fueled ascent vehicle.
This last concept, an effort to improve the piloted flyby mission's scientific productivity, was proposed by Bellcomm at the Planetary JAG's meeting at KSC on 29-30 June 1966. 19 The concept originated in a paper by R. R. Titus presented in January 1966. 20 Titus, a United Aircraft Research Laboratories engineer with a talent for unfortunate acronyms, dubbed his concept FLEM, for "Flyby-Landing Excursion Mode." He had been part of the Lockheed EMPIRE team.
Titus' mission plan had a piloted MEM lander separating from the flyby spacecraft during the Mars voyage and changing course to intersect the planet. Titus calculated that MEM separation 60 days before Mars flyby would permit it to stay for 16 days at Mars, while separation 30 days out yielded a 9-day stay time. At Mars the MEM would fire its rocket engine to enter orbit, then land. As the flyby spacecraft passed Mars, the excursion module would blast off in pursuit. The amount of propellant required for FLEM was much less than for an MOR landing mission because only the MEM would enter and depart Mars orbit. Titus calculated that a FLEM mission boosted to Mars in 1971 using a nuclear-thermal rocket might weigh as little as 130 tons—light enough, perhaps, to permit a piloted Mars landing with a single Saturn V launch.
In the 1966 JAG piloted flyby plan, the automated MSSR would land on Mars about two hours before the flyby craft flew past the planet and would immediately set to work gathering rock and soil samples using scoop, brush, sticky tape, drill, and suction collection devices. Less than two hours after MSSR touchdown, its ascent vehicle first stage would ignite. If all went well, the ascent vehicle's small third stage would deliver the samples to a point in space a few miles ahead of the flyby craft about 17 minutes later, 5 minutes after the flyby craft's closest Mars approach. As their craft overtook the sample package, the astronauts would snatch it in passing using a boom-mounted docking ring. They would then deposit it inside the Experiment Module's biology lab.