Moon Suit: 1949

Image credit: R. A. Smith/The British Interplanetary Society.
The British Interplanetary Society (BIS), founded by Phillip Cleator in Liverpool in 1933, is the world's oldest organization devoted to the promotion of spaceflight. In 1936, the BIS moved its headquarters to London and launched a Technical Committee, which soon began design of a Lunar Spaceship. The Society published results of its Lunar Spaceship study in its journal in 1939, then suspended its activities for the duration of the Second World War.

A decade later, on 19 November 1949, the reconstituted and always prescient BIS hosted the Symposium of Medical Problems Associated with Space-Flight. The third paper presented was a collaboration between self-taught engineer H. E. Ross and artist R. A. Smith, two men instrumental in the pre-war Lunar Spaceship study. It focused on the problems of designing a space suit for lunar surface exploration.

The Moon, they explained, has no atmosphere (they added, however, that an atmosphere might be "present below the surface, in the caverns, galleries, and pipes of an extinct volcanic system"). Its surface undergoes extremes of temperature during its nearly month-long day/night cycle. At noon on the lunar equator, the temperature soars to an "oven-high" 120° Celsius (C). At night, it plummets to a "ferocious" -150° C.

Ross and Smith wrote that the Moon's night hemisphere has a uniform temperature. During lunar day, on the other hand, landscape "cragginess," color, and composition could create local temperature variations. This disparity meant that designing separate space suits for night and day would likely be easier than designing a single day-and-night suit (and that designing a night suit might be easiest of all). Nonetheless, Ross and Smith elected to take on the challenge of designing an "ensemble" capable of protecting its wearer at any point in the day/night cycle and anywhere on the lunar surface.

The "skin" of their Moon suit would comprise four layers: a thin, smooth exterior layer (or "cuticle") of closely woven cloth (A in the drawing below); a "thickish" layer of "cellular heat-resisting material," such as wool (B); a rubber "airtight sheath" (C); and, for the wearer's comfort, a soft inner layer (D) that would not absorb moisture. To enhance mobility, the layers would form bellows joints at knees, ankles, hips, elbows, shoulders, and wrists.

Persons familiar with the Apollo A7L lunar suit will note the absence of any active cooling layer for carrying away body heat generated during exertion. In the Apollo suit, this took the form of a fabric layer laced with water tubes. As was typical of space suit designers until at least the mid-1960s, Ross and Smith underestimated the significance of heat generated by the suit wearer's body. They assumed that air flow through an air conditioning unit (8) and, under the hottest conditions, through an auxiliary air-cooling "refrigerator" (10), would, if combined with passive moderation of absorbed or radiated heat, be sufficient to control their Moon suit's internal temperature.

Cutaway of Ross and Smith's lunar space suit including a closeup of its "skin" structure (lower right). Number and letter call-outs are defined in the post text. Image credit: R. A. Smith/The British Interplanetary Society.
The suit would be colored black from just above the knees up to the shoulders (20) and silver elsewhere (19). Black fabric would, of course, absorb sunlight, while silver fabric would reflect it. It would include a silver cape (22) that the wearer could draw over the black area to reflect sunlight or hold in escaping heat, "studs" protruding from the chest (23) to separate the cape from the suit's outer surface (thus creating a vacuum barrier), a silver helmet (3) with a vacuum barrier between its inner metal and outer plastic layers, and pull-on boots (18) with four-centimeter-thick asbestos soles (17) and narrow treads (16) to retard heat transfer through contact with the Moon's surface.

If handling hot or cold tools or rocks became necessary, the lunar explorer could don mitts to protect his suit's permanently attached gloves. Knee pads could be added for kneeling or crawling.

Ross and Smith settled on a pure oxygen atmosphere at a pressure of 160 millimeters of mercury (for comparison, Earth's air mix is about 21% oxygen and 79% nitrogen at 760 mm of mercury). At the start of any moonwalk, the backpack would carry enough compressed gaseous oxygen to supply the lunar explorer for 12 hours.

The suit wearer would, of course, exhale carbon dioxide and water vapor, neither of which could be permitted to build up within the suit. Ross and Smith considered continuously venting "foul air" from the suit and replacing it with pure oxygen. (The Berkut suit Alexei Leonov wore during the world's first spacewalk on 18 March 1965 used this approach.) After rejecting continuous venting — it would, they calculated, require either a prohibitively large oxygen supply or very short moonwalks — they adopted a sodium peroxide-based system that would absorb exhaled carbon dioxide and water vapor and release supplemental oxygen as a by-product.

Ross and Smith proposed that, rather than exit and enter through an opening sealed by a zipper — which would tend to leak — the moonwalker should squeeze into the suit through its neck opening. The helmet would then lock into place, sealing the wearer inside. To prevent eye damage from exposure to harsh sunlight, they envisioned a helmet with only a narrow slit for viewing (28) and a bill and a pull-down visor (1). The suit would employ "internal body-hardness" to stop air pressure within it from pushing the helmet upward; this would keep the slit at the suit-wearer's eye level. Shoulder pads (7) would prevent Moon suit rigid components from chafing. How one might squeeze into the suit through a rigid neck and shoulder structure was not explained.

A collapsible chest-mounted airlock (24) and arm holes large enough to permit the lunar explorer to extract his arms from the suit arms (9) would enable him to pass objects in and out of the suit. These might include Moon rocks needing close examination and food and drink. An electric lamp (25) for lighting the way at night and in stark daytime shadow would be mounted on the chest above the round airlock hatch. Internal (14) and external (not shown) pockets would hold adhesive patches the wearer could apply if the suit became punctured by a micrometeoroid or torn by a tumble on sharp rocks.

Ross and Smith chose not to apply their considerable creativity to providing their Moon suit with means for accommodating two important bodily functions: specifically, urination and defecation. They wrote that their suit might be worn continuously for days during "camping trips" away from the Lunar Spaceship, so this omission is difficult to explain.

During camping trips, a suited explorer would not sleep on the ground or in direct sunlight; instead, to help maintain a comfortable temperature inside the suit, he would rest on a simple "camp-bed" in an unpressurized tent made of silver fabric. Similarly, he would not rest during long hikes by sitting on hot or cold boulders. The suit wearer would instead carry a walking stick, the handle of which could unfold to turn it into a one-legged stool (see image at top of post). The handle might be electrically heated for night use.

A radio antenna (4) atop the suit's backpack would permit both private communication between individuals and "party" communication among members of a group up to the distance of the lunar horizon (about 1.5 miles away on a level lunar plain, Ross and Smith estimated). The suit wearer could communicate directly with an antenna on the 50-foot-tall Lunar Spaceship at a distance of up to six miles on a level plain. If communication beyond the horizon or in an area with many surface obstructions — for example, hillocks and large boulders — became necessary, the moonwalker could leave behind small radio repeater stations as he moved over the surface.

The moonwalker would wear a "telephone head-set" (5) and a "laryngaphone" (throat microphone) (27). The radio, located at the top of the backpack directly beneath the antenna, would be controlled using knobs on the lower part of the backpack (11).

Ross and Smith ended their paper by estimating their Moon suit's weight. It would, they calculated, have an Earth weight of about 150 pounds. On the Moon, however, where gravity pulls with less than 20% as much force as on Earth, the suit would weigh about 25 pounds.

In July 2019, in time for the 50th anniversary of the Apollo 11 lunar landing (and the 70th anniversary of the Ross and Smith Moon suit presentation), the British National Space Center unveiled a life-size replica of the Ross and Smith Moon suit built in collaboration with the BIS and historical costume-maker Stephen Wisdom. For more information on the replica, visit the BIS website by following the link below.

Images in this post are Copyright © The British Interplanetary Society ( and are used by kind permission.


"Lunar Spacesuit," H. E. Ross and R. A. Smith, Journal of the British Interplanetary Society, Vol. 9, No. 1, January 1950, pp. 23-37; paper presented at the BIS Symposium of Medical Problems Associated with Space-Flight in London, United Kingdom, 19 November 1949.

High Road to the Moon: From Imagination to Reality, "The Collected Paintings of R. A. Smith with Text by Bob Parkinson," The British Interplanetary Society, 1979, pp. 22-24.

More Information

High Noon on the Moon (1991)

The Spacewalks That Never Were: Gemini Extravehicular Planning Group (1965)

Chrysler's Transportation and Work Station Capsule (1965)

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