|"Zero-G and I feel fine" — astronaut John Glenn in Earth orbit on board Mercury-Atlas 6 spacecraft Friendship 7, 20 February 1962. Image credit: NASA.|
At the time the MSC engineers completed their study, the U.S. record for weightless space endurance was held by John Glenn, the first American in orbit. During the Mercury-Atlas 6 mission (20 February 1962), he racked up a little less than five hours of weightless experience. On 24 May 1963, about two weeks after Mason and Ferguson completed their study, Scott Carpenter would match Glenn's feat during the Mercury-Atlas 7 mission.
The world record for weightless space endurance 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 1963. Apart from assurances that Nikolayev was in good health, the Soviet Union shared little information on 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 beating the Russians to the Moon became a major U.S. goal. 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 try to live in space for the period of time needed to accomplish 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 extended periods, then it might 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.
Before President John F. Kennedy put NASA on course for the lunar surface, an Earth-orbiting laboratory had been central to the agency's plans for the 1960s. By the end of 1962, the probable cost of the lunar program had begun to become clear. Grumbling had begun in Congress, placing pressure on President John F. Kennedy. The President in turn placed pressure on top 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, then NASA might wish to have handy a plan for an Earth-orbiting laboratory to serve as a replacement.
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 laboratory's drum-shaped Mission Module (MM). CSM modifications included a much-shortened Service Module (SM) with only enough propulsive capability and supplies for the trip to the laboratory in 300-mile-high low-Earth orbit.
Mason and Ferguson focused their study on the extent of the shift in the station spin axis astronaut movement parallel to that axis would produce. They called that shift the "wobble angle."
They 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 the astronauts would feel would vary by 15% between their feet and their heads, with maximum acceleration being felt at their feet, farthest from the spin axis. Maximum acceleration was limited to one Earth gravity; minimum acceleration, to one lunar gravity (0.2 Earth gravities).
The 11 images that follow each include two views. The launch configuration is on the left and orbital configuration is on the right. In all but two, 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