Journeying to the Moon in a Suit of Glass

It all began with a small spark. 

In the normal mix of air that we breathe every day, this might have caused some concern but would not have been especially hazardous. But this particular spark occurred within the 100% oxygen atmosphere of the Apollo 1 crew capsule. During a pre-flight testing routine on January 27, 1967, an electrical short set off a fire that consumed the oxygen and the many flammable components inside the cabin, proving fatal to the three astronauts on board – Roger Chaffee, “Gus” Grissom, and Ed White. This small spark brought the Apollo program to a halt and would lead NASA to see glass as an essential part of crew safety. [1]

Apollo 1 Crew (left to right) “Gus” Grissom, Ed White, Roger Chaffee).Courtesy National Aeronautics and Space Administration. Retrieved from Wikimedia Commons
Apollo 1 Crew (left to right) “Gus” Grissom, Ed White, Roger Chaffee. Courtesy National Aeronautics and Space Administration. Retrieved from Wikimedia Commons

In the final report on the fire, NASA found that in their rush to the Moon there had been few fire-safety tests of the materials that went into Apollo spacecraft. The engineers and contractors often relied on what had successfully worked for the earlier Mercury and Gemini spaceflight programs. At this early stage of the Apollo program (called Block 1), astronauts wore modified pressure suits that NASA developed for the Gemini program (1961-1966). These suits used fire-resistant Nomex™ (a kind of nylon) because the astronauts only needed to wear them inside the spacecraft. But the cabin was also filled with other flammable materials that had not been adequately tested in pure oxygen environments. At the moment of the fire, these conditions created an intense fire that compromised the astronauts’ suits. The Apollo 1 fire rapidly changed NASA’s requirements for the next generation of spacesuits, especially the kind of thermal protection it should offer.  

To solve this problem, NASA turned to glass. The Owens-Corning Corporation, established in 1938, had pioneered turning thin glass threads into woven nonflammable textiles, known as “fiberglass.” During World War II, Owens-Corning fiberglass found new applications as fire-proof insulation in warships and aircraft. For example, deep-sea Navy diving suits used wires wrapped in fiberglass specifically to prevent sparks from igniting the helium-oxygen breathing mixture used instead of compressed air. [2]   

Birth of a New Industry: Fibreglass

In the wake of the Apollo 1 fire, NASA’s Manned Spaceflight Center and Owens-Corning developed a new material called “Beta Cloth” – a form of fiberglass coated with a slick silicone (Teflon™) to reduce potential damage to the glass fibers. Because Beta Cloth is made of glass, it is not only non-flammable but has a much higher melting temperature than the Nomex materials used in previous suits. This initial fabric that Owens-Corning developed replaced more than 150 different types of textiles that had been used to make medical kits, toiletry bags, tissue dispensers, or that contained other flammable materials that the astronauts needed to bring with them.   

Comparison of the original design of Block II Apollo spacesuits. On the left astronaut James B. Irwin wears the pre-fire design, while John Bull (right) wears the revised suit featuring a beta cloth outer layer. Courtesy NASA on the Commons
Comparison of the original design of Block II Apollo spacesuits. Astronaut James B. Irwin (left) wears the pre-fire design, while astronaut John Bull (right) wears the revised suit featuring a Beta Cloth outer layer. Courtesy NASA on the Commons

The first version of Beta Cloth, which had the silicone applied after weaving, still suffered from abrasion damage, especially in critical joints. Owens-Corning developed a new version of Beta Cloth that applied the Teflon coating to individual glass strands before they were woven together. The improved “Super Beta” material was used for the outer layer (called the Integrated Thermal Micrometeoroid Garment or ITMG) of the Apollo suits. [3]

After its use in the Apollo program, Beta Cloth continues to serve as an important part of spaceflight. The material was used extensively on Skylab, the Space Shuttle, and still protects astronauts on the International Space Station. Beta cloth materials are also onboard the Mars rovers.

As important as Beta Cloth is as a material, it also represents a significant change to the processes used to ensure the safety of astronauts.

Apollo 14 Beta Cloth. Owens-Corning Fiberglas Corporation. Cloth made about 1967-1971 2019.8.4. On Display at the Corning Museum of Glass
Apollo 14 Beta Cloth. Owens-Corning Fiberglas Corporation. Cloth made about 1967-1971 2019.8.4. On Display at The Corning Museum of Glass

At the exhibition, Journey to the Moon: How Glass Got Us There, currently on view at The Corning Museum of Glass until April 30, 2020, visitors can see a swatch of Beta Cloth flown to the moon on board Apollo 14.


[1] Henderson, N. (2017) The Legacy of the Apollo 1 Disaster. Smithsonian Magazine. https://www.smithsonianmag.com/science-nature/legacy-apollo-1-disaster-180961917/ 

[2] Owens-Corning Fiberglas Corporation (1943). Fiberglas: A New Basic Material. Its Development, Properties, Manufacture and its Uses in War or Peace. Toledo, OH.  
Rakow Research Library Trade Catalog Collection – TC-5937  

[3] Naimer, J. Apollo Applications of Beta Fiber Glass. in NASA Conference on Materials for Improved Fire Safety Houston, T., Manned Spacecraft Center (U.S.)., United States. National Aeronautics and Space Administration. (1970).  Proceedings of the NASA conference on materials for improved fire safety. [Washington]: National Aeronautics and Space Administration. https://hdl.handle.net/2027/uiug.30112067697901?urlappend=%3Bseq=155 

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