Welcome to another episode of Sciency Words, a special series here on Planet Pailly where we take a closer look at the definitions and etymologies of science or science-related terms so we can expand our scientific vocabularies together. Today’s term is:
I’ve seen this term, or terms very similar to it, in a lot of different places. It’s usually obvious what it means from context. A shirt-sleeve environment is an artificial environment where humans can wear ordinary clothing in safety and comfort. The cabin of a commercial airliner is a good example. So is the interior of the International Space Station.
In the early days of aviation, pilots were far more exposed to the elements than they are today. They had to wear specialized clothing, especially for high altitude flights. It gets really cold up there above the clouds, and the air is very thin. Pressure suits were often essential, and in some cases those early pilots needed to bring supplemental oxygen with them.
There were several experiments in the early 20th Century to create safe, pressurized cockpits. I guess these were technically shirt-sleeve environments, but they still sound to me like tight and uncomfortable spaces. Maybe you could have worn your normal, everyday clothing in those cockpits, but I doubt you’d want to.
So the first true shirt-sleeve environment (in my judgment) would have been the Lockheed XC-35, built in 1937 for the U.S. Army Air Corps. It had a pressurized cockpit, crew area, and passenger cabin, so the crew would have had plenty of room to move around comfortably in their comfortable clothes.
Apparently the Army called this a “supercharged cabin,” not a shirt-sleeve environment. Based on what Google ngram tells me, it seems the term supercharged cabin was replaced with shirt-sleeve environment by the end of the 1950’s, right around the time the American space program was getting started.
As this 1960 paper from Boeing Airplane Company explains, “The term ‘shirt-sleeve environment’ means that the crew would be comfortable in this environment without any special equipment such as pressure suits.” And according to this 1958 paper on the structural stability of spacecraft, “Shirt-sleeves can become the normal flight clothing in sealed cabins under [sea-level type] conditions. In terms of human performance, the advantages of a sea-level atmosphere have been clearly demonstrated by the experiences of Ross and Lewis during the recent Strato-Lab High 2 and 3 flights.”
In modern space exploration literature, the International Space Station is typically cited as the most impressive shirt-sleeve environment yet constructed. The term is also used to describe the kinds of habitats we’d like to build for ourselves on the Moon, Mars, and elsewhere in the Solar System.
So remember: when you’re packing your bags for space, you don’t have to be too picky about which shirts you bring.