|“Zero-G and I really feel positive” — astronaut John Glenn, the primary American to achieve Earth orbit, throughout his five-hour flight on board Mercury-Atlas 6 spacecraft Friendship 7, 20 February 1962. Picture credit score: NASA.|
In early Could 1963, Robert Mason and William Ferguson, engineers on the NASA Manned Spacecraft Heart (MSC) in Houston, Texas, accomplished a examine of 11 artificial-gravity Earth-orbital laboratory designs. Some may need argued that NASA engineers had higher issues to do. In any case, for 2 years the area company’s most important purpose had been to land a person on the Moon and return him safely to the Earth earlier than the Soviet Union did, and the U.S. program nonetheless lagged behind its Soviet counterpart.
When the MSC engineers accomplished their examine, the U.S. document for weightless area endurance was held by Wally Schirra, the third American to achieve Earth orbit. Throughout the Mercury-Atlas 8 mission (3 October 1962), he racked up rather less than 9 hours of weightless expertise. A few week after Mason and Ferguson accomplished their examine, Gordon Cooper would set a brand new document by orbiting the Earth for about 34 hours through the Mercury-Atlas 9 mission (15-16 Could 1963).
The world document for weightless area endurance on the time was, nevertheless, held by cosmonaut Andriyan Nikolayev, whose Vostok 3 spacecraft lifted off from Baikonur Cosmodrome on 11 August 1962. He orbited the Earth 64 occasions in 3 days, 22 hours, and 28 minutes, and landed on 15 August 1962. Other than assurances that Nikolayev was in good well being, the Soviet Union shared little details about his bodily situation throughout or after his flight.
Lack of information on human responses to steady weightlessness goes a great distance towards explaining why NASA continued to review Earth-orbiting laboratories two years after President John F. Kennedy made the Moon a significant U.S. purpose on 25 Could 1961. It appeared prudent to some to retain the choice to launch a laboratory for research of human well being in weightlessness at the very least till astronauts might reside in area for a time period equal to the length of an Apollo lunar touchdown mission.
Lack of information additionally explains why Mason and Ferguson studied artificial-gravity laboratory designs. If it have been discovered that people couldn’t face up to weightlessness for lengthy intervals, then it could develop into mandatory to ascertain a lab in area the place the human well being results and engineering necessities of spin-induced acceleration — which is what “synthetic gravity” is — might be examined.
There have been additionally coverage causes for learning Earth-orbital laboratories. Earlier than President Kennedy put NASA on target for the Moon, an Earth-orbiting lab had been central to the company’s plans for the Sixties. Some engineers believed that the laboratory ought to have remained NASA’s first precedence after Undertaking Mercury, and so they seemed for alternatives to show again the clock.
By the tip of 1962, the possible value of the lunar program had develop into more and more clear. Grumbling had begun in Congress, putting strain on Kennedy, who in flip positioned strain on NASA brass to comprise area program prices. It appeared potential that the Apollo lunar purpose is likely to be discovered wanting by both Kennedy or, if he misplaced his bid for reelection in November 1964, by his successor. If that’s the case, the reasoning went, NASA may do nicely to have readily available a plan for an Apollo-derived Earth-orbiting laboratory as an inexpensive substitute for the lunar program.
In all however certainly one of their 11 designs, Mason and Ferguson had the laboratory and crew attain orbit collectively; the astronauts would experience 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 solely sufficient propulsion, energy, and life-support functionality for the journey to the lab’s 300-mile-high operational orbit and return to Earth.
Mason and Ferguson centered their examine on the extent of the shift within the laboratory spin axis that astronaut motion parallel to the spin axis would produce. They referred to as that shift the “wobble angle.”
|This illustration from Mason and Ferguson’s paper depicts the “wobble angle.” The road marked “Z” corresponds to the spin axis, which passes by way of the middle of gravity of the orbiting laboratory. The Z on the prime would, if the laboratory’s spin remained solely steady, at all times level straight on the Solar. Astronaut motion parallel to the Z line would, nevertheless, trigger the spin axis to shift alongside the curving line labeled “Spin-axis hint.” On this design, which corresponds to Laboratory Design 1 under, astronauts would wish to cope with a wobble angle of as much as 43°. Mason and Ferguson likened this movement to the “rolling of a ship.”|
The MSC engineers assumed that the orbiting laboratory MM and different construction, habitation and science gear, and the modified CSM would collectively weigh about 15 tons. Of that, 5 tons have been allotted to the CSM. All of their designs retained the Saturn IB rocket second stage, the S-IVB, to be used as a counterweight. With its liquid hydrogen/liquid oxygen propellants spent, the S-IVB stage would weigh 10 tons.
Mason and Ferguson set the spin fee at a most of 4 rotations per minute. At that fee, and at a distance of 40 toes from the spin axis, the acceleration an astronaut would really feel would fluctuate by 15% between their toes and their head, with most acceleration being felt at their toes, farthest from the spin axis. Most acceleration could be restricted to 1 Earth gravity; minimal acceleration wouldn’t fall under one lunar gravity (0.2 Earth gravities).
The 11 pictures that comply with every embody two views. The laboratory launch configuration is on the left and orbital configuration is on the best. In all however two of the photographs, the Z axis/spin axis factors on the viewer in each views; for Laboratory Designs 8 and 9, the Z axis within the launch configuration view is turned 90° relative to the orbital configuration view.
|Laboratory Design 1: the primary Mason and Ferguson artificial-gravity lab design is the best, although it additionally has one of many best most wobble angles (about 43°). Crew couches within the CSM are on the minimal distance (40 toes) from the spin axis (Z), however all the two-deck MM is simply too close to the spin axis to keep away from a variation in acceleration stage between astronaut head and toes better than 15%. Gear weight is 12,496 kilos, construction weight is 7504 kilos, and pressurized quantity is 2504 cubic toes. Thrusters positioned on the ends of the lab would expend 52.9 kilos of propellant to begin it spinning at a fee of 4 rotations per minute.|
|Laboratory Design 2: An alternate technique of photo voltaic array deployment improves stability (wobble angle barely greater than 9°) by rising lab width and mass alongside the Y axis. Construction weight is 8235 kilos and gear weight is 11,765 kilos. Pressurized quantity is 2505 cubic toes. Sadly, no a part of the CSM or MM is much sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and pricet. Thrusters expend 55.3 kilos of propellant to spin up the laboratory.|
|Laboratory Design 3: Gear modules of unspecified operate deploy alongside the Y axis; this helps to cut back most wobble angle to about 3.5°. Construction weight together with the gear modules is 12,492 kilos. Gear weight — 7508 kilos — is the least of any of the designs. Pressurized quantity is 2396 cubic toes. No a part of the CSM or MM is much sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Thrusters expend simply 49.7 kilos of spin-up propellant.|
|Laboratory Design 4: A tunnel between the CSM and the MM locations the CSM crew couches 43.3 toes from the spin axis. Sadly, the utmost distance from the spin axis throughout the MM is simply 18.3 toes. Inserting the comparatively huge CSM removed from the spin axis and comparatively slim construction alongside the Y axis contribute to a wobble angle of practically 44°. Construction weight is 8687 kilos and gear weight is 11,313 kilos. Pressurized quantity is 2396 cubic toes. Thrusters expend 50.7 kilos of propellant to spin up the laboratory.|
|Laboratory Design 5: The tunnel linking the CSM and MM is extendable, rising CSM crew sofa distance from the spin axis to 52.9 toes. The wobble angle is equivalent to that of Design 4. Construction weight is 8290 kilos and gear weight is 11,710 kilos. Pressurized quantity is 2400 cubic toes. The MM solely surrounds the spin axis; in concept, an astronaut on the spin axis could be weightless whereas the station spun round them. No a part of the MM is much sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Thrusters expend 65.7 kilos of propellant to spin up the laboratory.|
|Laboratory Design 6: Each the CSM and the MM telescope away from the spin axis. The 45° most wobble angle is the best of the 11 designs. Construction weight is 7505 kilos and gear weight is 11,765 kilos. Pressurized quantity is simply 1633 cubic toes, the least of any of the designs. About half the MM is much sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Thrusters expend 68.3 kilos of propellant to spin up the lab.|
|Laboratory Design 7 is just like Design 6, however its modified photo voltaic array configuration will increase its width and mass alongside the Y axis, decreasing its most wobble angle to barely lower than 29°. Construction weight is 7869 kilos, gear weight is 12,131 kilos, and pressurized quantity is 1743 cubic toes. Thrusters expend 68.3 kilos of propellant to spin up the laboratory.|
|Laboratory Design 8 combines options of Designs 3 and seven to realize a wobble angle of barely lower than 2.5°. A brand new characteristic of this design is a docking port for a visiting modified CSM at the spin axis (Z). In lots of artificial-gravity station designs, docking ports on the spin axis rotate spin “backwards” in order that they seem to stay nonetheless, facilitating docking. Mason and Ferguson gave no indication that their design would come with a counter-spun docking port, nevertheless. Construction weight is 12,169 kilos, gear weight is simply 7831 kilos, and pressurized quantity — with out a second CSM — is 2048 cubic toes. The entire CSM and practically the entire MM are far sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Thrusters expend 66.9 kilos of propellant to spin up this design.|
|Laboratory Design 9 contains new structural parts: a “fork” and cables that allow the spent S-IVB stage to be pivoted 90° relative to its launch axis. This reduces the wobble angle to barely lower than 1° — the least of any of the 11 designs. Sadly, no a part of the CSM or MM is far sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Construction weight is 8306 kilos and gear weight, 11,694 kilos. Pressurized quantity is 3118 cubic toes. Thrusters expend 64 kilos of spin-up propellants.|
|Laboratory Design 10 employs a “inflexible help” and cables to pivot the spent S-IVB stage 90° relative to its launch axis. Most wobble angle is 1°. The CSM crew couches and a part of the MM are far sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes. Construction weight is 8120 kilos and gear weight is 11,880 kilos. Pressurized quantity is 2400 cubic toes. Thrusters would expend 71.8 kilos of propellants to spin up this design.|
|Laboratory Design 11 contains no CSM in its launch configuration view as a result of construction and gear weight is simply too nice. The massive MM is extendible. The CSM is displayed within the orbital configuration view as it could seem after it launched individually and docked with the MM in orbit. The pivoted S-IVB stage and the photo voltaic panel association assist to compensate for the big MM, yielding a wobble angle solely barely better than Design 9. Construction weight is 14,047 kilos and gear weight is 15,953 kilos. Pressurized quantity is by far the best of the 11 designs (3828 cubic toes), as is the quantity of spin-up propellant required (116.1 kilos). Spin-up would happen after the CSM arrived. All elements of CSM and MM are far sufficient from the spin axis to keep away from a better than 15% variation in acceleration stage between astronaut head and toes.|
Undertaking Apollo Conceptual Rotating House Car Designs Utilizing Apollo Elements for Simulation of Synthetic Gravity, NASA Undertaking Apollo Working Paper No. 1073, NASA Manned Spacecraft Heart, 8 Could 1963.
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