Guidelines observed in the study were: (1) minimum interference with the Apollo program; (2) use of either Saturn IB or V launch vehicles; (3) laboratory to be sized so that the one module, two modules, or one module on a LEM descent stage could fit into an unmodified LEM adapter; (4) use of a three-man crew; (5) capability to dock to either end of the module and to rendezvous modules; and (6) mission lengths of 14 to 45 days, with growth capacity for longer durations. The study was made on the presumption of a laboratory module launched in the LEM adapter area which would be aligned with an access hatch in the module. An expandable airlock could also be incorporated when desired. The external envelope would be 465 cm, which would permit three modules to be placed in the S II stage that was 10 m in diameter; the floor to ceiling height would be 213 cm; the total pressurized volume of the module would be 39 cu m; and total floor area 16 sq m. The module would be designed for an internal pressure of 48 kilonewtons per sq m (7 psia) for a 180-day mission. It would weigh 1313 kg, and its support rack would weigh 413 kg. For lower gross weights expected with Saturn IB launches, the support rack weight could be reduced to 261 kg. The multipurpose mission module, as proposed, would allow much flexibility in missions, including formation of large space stations, and would permit use of an assortment of internal and external equipment without affecting the integrity of the shell and requiring only minor structural additions or changes. A feature of the Boeing report was the section devoted to volume. It said that . after reserving the requirements for module subsystems, experiment report, and 5.6 cu m (200 cu ft) for each astronaut, about 16.9 cu m (600 cu ft) of pressurized and 62.2 cu m (2200 cu ft) of unpressurized volume would be available for experiment equipment...." The report then listed some of the advantages of providing adequate pressurized volume: Volume Equals Economy: Maximum use of standard hardware; no miniaturization required; allows standard subsystem modules for varying missions; protected environment simplified equipment design. Volume Equals Manned Participation: Equipment accessible for direct manual operation; man's capability to participate can be evaluated. Volume Equals Efficiency: Minimum interference work-area layouts possible; experiment setup and tear-down time reduced or eliminated; improved crew morale increases efficiency. Volume Equals Reliability: Inside equipment can be adjusted and maintained by the crew; equipment is protected from temperature cycles and hard vacuum of space. Volume Equals Experiment Flexibility: Volume allows modular approach to experiment and subsystem design; experiment substitution requires no rearrangement of other equipment; minimized lead time for changes. Volume Equals Increased Experiment Capabilities: Enough room for crew movement and locomotion tests; allows volume for centrifuge or double trampoline. Volume Equals Safety: Eliminates extravehicular activities for normal laboratory operation.