08 November 2016

One-Man Space Station (1960)

Final Mercury: the black Mercury-Atlas 9 spacecraft and its gleaming Atlas booster rocket in October 1963. Image credit: NASA
Probably the prize for "smallest space station design ever proposed" should go to McDonnell Aircraft's One-Man Space Station. On 24 August 1960, engineers with St. Louis-based McDonnell, the Mercury spacecraft prime contractor, described the mini-station to members of the Space Task Group (STG) at NASA's Langley Research Center in Hampton, Virginia.

A 10-foot-long, six-foot-wide pressurized cylinder with dome-shaped ends, the One-Man Space Station was meant to be launched stacked between a single-seat Mercury on top and an Agena-B upper stage below. The assemblage would be launched atop an Atlas-D rocket similar to that tapped to launch standard Mercury-only orbital missions.

The Atlas-Agena rocket was an early workhorse of lunar and planetary exploration. This image shows the launch of the Mariner 1 Venus probe on 22 July 1962. Less than five minutes later, the Atlas first stage veered off course. The range safety officer transmitted a self-destruct command and the Atlas, Agena upper stage, and Mariner 1 were destroyed. Image credit: NASA
One might be excused for calling the One-Man Space Station a mission module that enhanced Mercury spacecraft capabilities rather than a bona fide space station. It was meant to be occupied for just 14 days by the single astronaut launched with it in the Mercury spacecraft, then permanently abandoned when the astronaut separated from it in the Mercury to return to Earth.

The group of NASA engineers that heard McDonnell's presentation shared some traits with the proposed One-Man Space Station: it was small and meant to be only temporary. The STG was founded on 5 November 1958, a little more than a month after NASA opened for business. Based at NASA's Langley Research Center in Hampton, Virginia, the STG's aim was to carry out Project Mercury, the U.S. effort to launch a man into space ahead of the Soviet Union.

Though President Dwight Eisenhower took a dim view of what he saw as "space stunts" - for example, launching men into space - he became, along with Senate Majority Leader Lyndon Baines Johnson, one of NASA's chief architects. Eisenhower made no commitment to piloted spaceflight after Mercury. He insisted that Mercury be conducted as a civilian program to keep it separate from the serious military business of developing battlefield and intercontinental missiles and launching reconnaissance and early-warning satellites.

Atlas-D - a modified intercontinental ballistic missile - was not by itself powerful enough to place the Mercury/One-Man Station/Agena-B combination into Earth orbit. McDonnell proposed that the General Dynamics-built Agena-B ignite after the Atlas-D exhausted its propellants and separated. The Agena-B would then insert itself, the Mercury, and the One-Man Space Station into a 150-nautical-mile-high orbit inclined 30° relative to Earth's equator. The Agena-B would remain attached after orbit insertion: it was restartable and would retain enough propellants to maneuver in Earth orbit.

It is probable that the One-Man Space Station was the civilian version of a proposed piloted spy satellite. With its integral Agena-B stage for Earth-orbit injection and orbital maneuvers and its separable Mercury spacecraft for Earth return, McDonnell's station outwardly resembled the Discoverer automated satellites, the first of which was launched in January 1959. "Discoverer" was a cover name for the Corona spy satellite series. Atlas-launched Discoverer/Corona satellites employed an integral Agena for Earth-orbit injection and orbital maneuvers and a reentry capsule for exposed film return. An aircraft would capture the capsule as it descended on a parachute.

A piloted spy satellite must have seemed attractive by the summer of 1960, for the Discoverer/Corona program had suffered failure after failure. Not until Discoverer 14 - launched on 18 August 1960, just six days before McDonnell's presentation to the STG - did the program succeed in returning to Earth a capsule containing exposed film showing Earth-surface targets.

The One-Man Space Station's hull would encompass a total of 282 cubic feet of pressurized volume, of which 182 cubic feet would constitute living and working space. The astronaut would work inside the station in shirt-sleeves, not a pressure suit. A "laboratory test payload" - a suite of experiments which could be changed from flight to flight - would take up 40 cubic feet of the interior volume, while support equipment - for example, fuel cells capable of producing up to 1500 watts of electricity - would take up 60 cubic feet at the domed bottom end of the station.

Schematic of the "Tunnel Access" One-Man Station design with a human figure for scale. A = Mercury spacecraft; B = adapters for linking (from top to bottom) the Mercury spacecraft and the One-Man Space Station, the One-Man Space Station and the Agena stage, and the Agena stage and the top of the Atlas booster; C = inflatable tunnel linking the Mercury hatch with a similar hatch on the One-Man Space Station; D = pressurized work area; E = life support and electricity-generating equipment; F = One-Man Space Station laboratory test payload; G = Agena-B stage; H = Tunnel Access cover in launch position; I = Tunnel Access cover in deployed position; J = top of the Atlas-D rocket. Image credit: McDonnell Aviation/David S. F. Portree
McDonnell proposed two possible designs for its One-Man Space Station. The method the astronaut would use to move between the attached Mercury spacecraft and the One-Man Space Station pressurized volume would distinguish the two designs. McDonnell dubbed them "Tunnel Access" and "Hinged Lab."

Tunnel Access would need fewer Mercury spacecraft modifications than Hinged Lab. An inflatable fabric tunnel would reach Earth orbit folded against the Mercury and One-Man Space Station under a streamlined metal cover. Upon reaching orbit, the astronaut would inflate the tunnel to create a passage between the standard-design 24-inch Mercury side hatch and a 24-inch hatch on the Station's side. The metal cover would remain attached to the tunnel to stiffen it and partly shield it from meteoroid punctures.

When time came to return to Earth, the astronaut on board the Tunnel Access Station would don his protective pressure suit, return to his cramped seat in the Mercury spacecraft, seal the Mercury hatch, and fire pyrotechnic bolts or cord to sever the inflatable tunnel. He would then separate his Mercury spacecraft from an adapter linking it to the Station, turn it so that its broad aft end faced in its direction of motion, and ignite a single solid-propellant retrograde motor to begin atmosphere reentry.

The Hinged Lab design would see the Mercury spacecraft swing on a hinge so that a modified Mercury side hatch could link up with a hatch on the side of the One-Man Space Station. When time came to return to Earth, the astronaut would seal the Mercury hatch, then swing his spacecraft back to its Earth launch position on top of the Station. He would fire explosive bolts to separate the Mercury from the hinged adapter, then would begin reentry.

"Hinged Lab" One-Man Space Station. A = hinge; B = ring-shaped adapter; C = transfer tunnel linking modified Mercury spacecraft hatch with One-Man Space Station hatch. Image credit: McDonnell Aviation/David S. F. Portree
The presence of the Agena-B stage permitted McDonnell to delete the standard Mercury 24-pound solid-propellant posigrade motor set, which in Mercury-only flights would ignite to propel the spacecraft away from its spent Redstone or Atlas booster. Other modifications would include the aforementioned revised hatch designs, which would add 16 pounds to both the Tunnel Access and Hinged Lab One-Man Space Station designs; deletion of the astronaut-monitoring camera from the standard Mercury telemetry & recording system (a savings of 28 pounds); storage space in the Mercury spacecraft cabin for returning to Earth 28 pounds of experiment results generated on board the Station; and addition of seven pounds of water to the Mercury environmental control system.

A new-design adapter would link the broad base of the Mercury spacecraft with the top of the One-Man Space Station. This would weigh 97 pounds for the Tunnel Access design, which could get by with a relatively simple adapter, and 129 pounds for the more complex Hinged Lab adapter.

The Tunnel Access One-Man Space Station without Mercury and Agena-B would weigh 3344 pounds; for the Hinged Lab Station, the weight total was 3309 pounds. The Hinged Lab Station would include an additional 22 pounds of attitude-control propellant - necessary because of the difficulty of stabilizing the out-of-balance side-mounted Mercury configuration. The Tunnel Access Station, for its part, would add 50 pounds for the inflatable tunnel cover and 135 pounds for the tunnel itself.

McDonnell told the STG that the Atlas-D/Agena-B combination could inject 6076 pounds into the One-Man Space Station's planned orbit. Subtracting the combined weight of the modified Mercury, Agena-B, and Station left 1234 pounds for experiment equipment on the Tunnel Access Station and 1342 pounds on the Hinged Lab Station. The company listed as possible One-Man Space Station research projects the study of human adaptation to 14-day weightless missions; monitoring of "long-time equipment performance" on board spacecraft; "lunar probe navigation equipment" testing; radiation, geophysical, and astrophysical measurements; and, by using the Agena-B rocket motor, development of orbital rendezvous techniques.

McDonnell suggested that One-Man Space Stations might also be devoted to single-purpose missions: for example, one might be equipped to carry out communications research, the next might serve as an astronomical observatory, and yet another might enable detailed observations of Earth's weather. The company also suggested that a One-Man Space Station might revert to its likely original purpose: that is, high-resolution imaging of objects on Earth's surface.


One Man Space Station, McDonnell Aircraft, 24 August 1960

NASA's Origins and the Dawn of the Space Age, Monographs in Aerospace History #10, David S. F. Portree, NASA History Office, September 1998

More Information

The 1991 Plan to Turn Space Shuttle Columbia Into a Low-Cost Space Station

A True Gateway: Robert Gilruth's June 1968 Space Station Presentation

Re-Purposing Mercury: Recoverable Space Observatory (1964)

Space Station Gemini (1962)

1 comment:

  1. The fact that anyone would prepose this at all speaks volumes about far Mercury was behind Vostok in capabilities.


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