Manned Spacecraft Center, 1968.
"In October 1968, the International Academy of Astronautics organized a symposium titled "Manned Laboratories in Space". S. Fred Singer, the program chairman and proceedings editor, commissioned nine papers - eight from the United States and one from the Soviet Union. Two of the papers focused on the design of the orbital laboratory itself; the other seven focused on applications: for Earth observation, for astronomical observation, and as "stepping stones" to manned interplanetary flight.
Robert R. Gilruth, the Director of the NASA Manned Spacecraft Center, presented an overview of the rationale and characteristics of manned space stations. He stated that "the characteristics of artificial gravity are important objectives for a near-term Earth orbital activity." Artificial gravity would:
- permit fluid processes - such as associated with personal hygiene, cleaning, food preparation, and chemistry - to be performed in a manner identical to that which we are accustomed to on Earth;
- provide the ability to walk with the hands free;
- permit normal man-machine interfaces with all types of equipment;
- permit the use of equipment developed for use in Earth laboratories but otherwise applicable to space station tasks;
- eliminate the need for special zero-gravity training;
- maximize the effectiveness of Earth training.
Gilruth regretted that the initial orbital workshop (later known as Skylab) would not provide artificial gravity, and described two concepts for providing it in future missions.
To provide an initial research environment, an Apollo spacecraft with an attached experiment module would be tethered to a spent booster stage that would serve as a counterweight for rotation. The tether length would be adjustable; the rotational radius to the experiment module would be at least 50 feet. Previous experiments with ground-based centrifuges and parabolic flights had indicated that the comfort zone for artificial gravity had a lower bound of 0.3 g and an upper bound of 4 rotations per minute. Nevertheless, there was considerable uncertainty in these results, particularly with regard to the effect of the Earth's 1-g field in ground-based tests. The tethered Apollo would provide a space-based environment for verifying the earlier results, as well as for experimenting with higher gravity levels (up to 1 g) and lower rotational rates.
The first operational space station would be launched in three parts by three Saturn V rockets, assembled in orbit to form a slender linear structure, and rotated end-over-end. A non-rotating hub extending from one side would accommodate a zero-gravity laboratory, a docking port, and a hangar for satellite maintenance. In its initial configuration, the station would accommodate at least 50 crew members; with additional construction, it could grow to accommodate at least 100. The habitable areas would be arranged as a cylindrical tower extending 240 feet from one side of the hub; the power section and counterweight would hang from a truss extending as much as 375 feet from the opposite side. The station would rotate 3.5 times per minute to provide 1 g in the lowest level of the habitat."
Yemen Arab Republic, 1969, souvenir sheet "Future space station USA":
Souvenir sheet CTO:
Proof, souvenir sheet CTO, souvenir sheet: