The British Interplanetary Society (BIS), founded by Phillip Cleator in Liverpool in 1933, is the world's oldest existing organization devoted to the promotion of spaceflight. In 1936, the BIS moved its headquarters to London and launched a Technical Committee, which soon began to design 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 at the Symposium 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"). Every bit as important from the standpoint of space suit design, the moon's surface undergoes extremes of temperature during its nearly month-long day/night cycle. On the lunar equator at noon, for example, the temperature soars to an "oven-high" 120° C (248° F). At night, it plummets to a "ferocious" -150° C (-238° F).

Ross and Smith noted that across the moon's night hemisphere the temperature is uniform, but that it varies widely across its day hemisphere. During the lunar day, such factors as landscape "cragginess," color, and composition could produce significant local temperature variations. This implied that designing separate space suits for night and day use would be easier than designing a single day-and-night suit (and that night suit design might be easiest of all). Despite this, Ross and Smith chose to take on the challenge of designing a lunar "ensemble" capable of protecting its wearer at any point in the day/night cycle and anywhere on the moon's surface.

Their lunar suit's pressure vessel 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, to ensure the wearer's comfort, a soft, non-water-absorbing inner layer (D). To enhance mobility, the layers would form bellows joints at knees, ankles, hips, elbows, shoulders, and wrists.

Cutaway showing Ross & Smith lunar suit design details. Letter and number call-outs are explained in the blog post text. Image: R. A. Smith/British Interplanetary Society Cutaway showing Ross & Smith lunar suit design details. Letter and number call-outs are explained in the blog post text. Image: R. A. Smith/British Interplanetary Society

Persons versed in the design of the Apollo A7L lunar suit will note the absence of a cooling layer; that is, one laced with water tubes for actively carrying away body heat generated during exertion. 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 & temperature conditioning unit (8) and, under the hottest conditions, through an air-cooling "refrigerator" (10), would, if combined with passive moderation of absorbed or radiated heat, be sufficient to control their suit's internal temperature.

To passively moderate its internal temperature, the suit would be colored black from just above the knees up to the shoulders (20) and silver elsewhere (19). Black would, of course, absorb the Sun's heat, while silver would reflect it. The suit 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 and thus create 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 prevent heat gain and loss through contact with the moon's surface.

If crawling up steep slopes on hands and knees or handling hot or cold tools or rocks became necessary, the lunar explorer would 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 suit 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 briefly considered continuously venting "foul air" from the suit and replacing it with pure oxygen. (This approach was, incidentally, put to use in the Berkut space suit Alexei Leonov wore during the world's first spacewalk on 18 March 1965.) After rejecting continuous venting - it would, they calculated, require either a prohibitively large quantity of oxygen or very short moonwalks - they adopted a sodium peroxide-based system which 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 through 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) to reduce glare. The suit would employ "internal body-hardness" to prevent air pressure within it from pushing the helmet up so that the slit rose above the wearer's eye level. Shoulder pads (7) would prevent the suit's hard parts from chafing its wearer. How one might squeeze into the suit through a rigid neck and shoulder structure was, however, 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. Such objects 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 would apply if the suit became punctured by a micrometeoroid or torn by a tumble on sharp rocks.

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

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. Instead, the suit wearer would 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 enable both private communication between individuals and broadcast "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, then the moonwalker could leave behind a series of 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 suit's weight. It would, they calculated, have an Earth weight of 150 pounds. On the moon, however, where gravity pulls with about 15% as much force as on Earth, their suit would weigh only about 25 pounds.

Reference:

"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 British Interplanetary Society's Symposium of Medical Problems Associated with Space-Flight in London, United Kingdom, 19 November 1949.