|"Zero-G and I feel fine" — astronaut John Glenn, the first American to reach Earth orbit, during his five-hour flight on board Mercury-Atlas 6 spacecraft Friendship 7, 20 February 1962. Image credit: NASA.|
When the MSC engineers completed their study, the U.S. record for weightless space endurance was held by Wally Schirra, the third American to reach Earth orbit. During the Mercury-Atlas 8 mission (3 October 1962), he racked up a little less than nine hours of weightless experience. About a week after Mason and Ferguson completed their study, Gordon Cooper would set a new record by orbiting the Earth for about 34 hours during the Mercury-Atlas 9 mission (15-16 May 1963).
The world record for weightless space endurance at the time was, however, held by cosmonaut Andriyan Nikolayev, whose Vostok 3 spacecraft lifted off from Baikonur Cosmodrome on 11 August 1962. He orbited the Earth 64 times in 3 days, 22 hours, and 28 minutes, and landed on 15 August 1962. Apart from assurances that Nikolayev was in good health, the Soviet Union shared little information about his physical condition during or after his flight.
Lack of data on human responses to continuous weightlessness goes a long way toward explaining why NASA continued to study Earth-orbiting laboratories two years after President John F. Kennedy made the Moon a major U.S. goal on 25 May 1961. It seemed prudent to some to retain the option to launch a laboratory for studies of human health in weightlessness at least until astronauts could live in space for a period of time equal to the duration of an Apollo lunar landing mission.
Lack of data also explains why Mason and Ferguson studied artificial-gravity laboratory designs. If it were found that humans could not withstand weightlessness for long periods, then it would become necessary to establish a lab in space where the human health effects and engineering requirements of spin-induced acceleration — which is what "artificial gravity" is — could be examined.
There were also policy reasons for studying Earth-orbital laboratories. Before President Kennedy put NASA on course for the Moon, an Earth-orbiting lab had been central to the agency's plans for the 1960s. Some engineers believed that the laboratory should have remained NASA's first priority after Project Mercury, and they looked for opportunities to turn back the clock.
By the end of 1962, the probable cost of the lunar program had become increasingly clear. Grumbling had begun in Congress, placing pressure on Kennedy, who in turn placed pressure on NASA brass to contain space program costs. It seemed possible that the Apollo lunar goal might be found wanting by either Kennedy or, if he lost his bid for reelection in November 1964, by his successor. If so, the reasoning went, NASA might do well to have on hand a plan for an Apollo-derived Earth-orbiting laboratory as a cheap replacement for the lunar program.
In all but one of their 11 designs, Mason and Ferguson had the laboratory and crew reach orbit together; the astronauts would ride in a modified Apollo Command and Service Module (CSM) spacecraft atop the lab's drum-shaped Mission Module (MM). CSM modifications included a much-shortened Service Module (SM) with only enough propulsion, power, and life-support capability for the trip to the lab's 300-mile-high operational orbit and return to Earth.
Mason and Ferguson focused their study on the extent of the shift in the laboratory spin axis that astronaut movement parallel to the spin axis would produce. They called that shift the "wobble angle."
Mason and Ferguson set the spin rate at a maximum of four rotations per minute. At that rate, and at a distance of 40 feet from the spin axis, the acceleration an astronaut would feel would vary by 15% between their feet and their head, with maximum acceleration being felt at their feet, farthest from the spin axis. Maximum acceleration would be limited to one Earth gravity; minimum acceleration would not fall below one lunar gravity (0.2 Earth gravities).
The 11 images that follow each include two views. The laboratory launch configuration is on the left and orbital configuration is on the right. In all but two of the images, the Z axis/spin axis points at the viewer in both views; for Laboratory Designs 8 and 9, the Z axis in the launch configuration view is turned 90° relative to the orbital configuration view.
Project Apollo Conceptual Rotating Space Vehicle Designs Using Apollo Components for Simulation of Artificial Gravity, NASA Project Apollo Working Paper No. 1073, NASA Manned Spacecraft Center, 8 May 1963.
Space Station Resupply: The 1963 Plan to Turn the Apollo Spacecraft into a Space Freighter
To "G" or Not to "G" (1968)
"A True Gateway": Robert Gilruth's June 1968 Space Station Presentation
A Forgotten Rocket: The Saturn IB