Your stadium roof may have been launched out of this world

Buzz Aldrin, Moon landing
Astronaut Edwin E. Aldrin Jr. poses next to the U.S. flag.  Spacesuits worn on the Apollo 11 mission featured PTFE as an outer protective layer. That material is now used in stadium roofing worldwide. (Photo By Nasa/Getty Images)

Editor’s Note: As the 50th anniversary of the moon landing approaches on July 20, our staff wondered what effects, if any, that event had on the sporting world today. What we found is that technology developed in 1969 for the moon landing is present in many areas of modern life, even in many sports stadiums around the world.

Black text that reads why this matters
The effects of the Apollo program can be seen in many aspects of modern life, including the durable, cost-effective roofing material used in stadiums and arenas around the world. Technology created for one industry has paid off for every fan’s use.

Imagine an event that demands the attention of a nation. One that has every family in America sitting in front of the television, glued to the action unfolding on the screen. The moon landing on July 20, 1969 was such an event. The Super Bowl has a similar effect every January. But is there something else these two events share besides the large audience?

Modern roofs and canopies at stadiums around the world are constructed with PTFE (polytetrafluoroethylene), commonly known as Teflon. PTFE is pliable and sturdy, cost-effective and can withstand extreme heat and cold, making it an ideal roofing material. It was first developed as a component in the A7-L spacesuit.

How the technology was developed for spacesuits

On Feb. 21, 1967, a flash fire in the Apollo 1 command module during a launch rehearsal killed three astronauts. NASA realized it needed to improve the safety features of not only the modules, but also the spacesuits. The organization needed to reduce the amount of flammable material in the cockpit.

Two private sector companies, Owens-Corning and DuPont Corporation, proposed a fabric called Beta cloth. Beta cloth is made by twisting ultra fine glass filaments into threads and then weaving them into fabric. The layer of Beta cloth was covered in high-performance PTFE in spacesuits.

Graphic representation of the various layers in Apollo-era spacesuits. Beta cloth and PTFE were key components in the suits. (Photo courtesy of the American Society of Mechanical Engineers)

With a melting point of more than 650 degrees Fahrenheit, Beta cloth was the perfect material to incorporate into the outer protective layers of spacesuits. Not only did it provide thermal and UV protection for astronauts, but it also shielded them from abrasive moon dust.

Transition to the commercial sector

Around the same time, former aeronautical engineer Walter Bird was working on a practical application for the material outside of the space program. He founded Birdair Structures Inc. in 1956, and developed a modified, stronger version of the material used in spacesuits to be used as an architectural tensile fabric for roof construction.

“When there are so many architectural materials out there, fabric is not something architects usually think of offhand,” William Barden, Birdair’s director of architectural development, said in a 2012 NASA press release. “Walter Bird’s pioneering role in the tensile structure industry was to take a technology that was perceived by people as ‘pie in the sky’ and create a market for it.”

Although Birdair did not construct the U.S. Pavilion at the 1970 World’s Fair in Osaka, Japan, Bird consulted on the project. The temporary structure became the world’s first air-supported roof. The dome’s steel rope structural system supported a thick fabric roof.

Three years later, Birdair constructed the first permanent tensioned membrane structure. The company worked with LaVerne College, now known as the University of LaVerne, in LaVerne, Calif., to construct a PTFE roofing system, known around campus as the “Super Tents,” to cover the school’s Sports Science and Athletics Pavilion

When Reliant Stadium, now known as NRG Stadium, opened in 2002 in Houston, Texas, it was the first NFL stadium with a retractable roof. The stadium’s PTFE fabric roof is supported by a network of cables and pylons. Not only is the roofing material lightweight and durable, making it ideal for a roof that moves, but it is also translucent. Natural light enters the stadium when the roof is closed, giving the Texans the option to have a grass field instead of turf.

Why is PTFE such a good roofing material?

PTFE, or Teflon, is pound for pound stronger than steel. It lets in natural light, weighs less than five ounces per square foot and keeps out extreme heat and cold. 

Overall, it’s a durable, low-maintenance and cost-effective alternative for roofing material

Mercedes Benz Stadium, Atlanta
Mercedes Benz Stadium site of Super Bowl LIII at sunset during Super Bowl LIII week on January 30, 2019 at the Georgia World Congress Center in Atlanta GA. (Photo by Rich Graessle/Icon Sportswire via Getty Images)

PTFE is not the only polymer material used in architecture today. PVC-coated polyester and ETFE (ethylene tetrafluoroethylene) film are also common materials used in roofing. ETFE film layers are a popular alternative to glass because of weight and durability. ETFE film is layered with cushions of air to help provide stability. 

Two of the most recognized structures constructed with ETFE film are the Beijing National Aquatics Center (Water Cube) used for swimming and diving in the 2008 Summer Olympics and the Mercedes-Benz Stadium in Atlanta, Georgia.

According to an article in Material District, ETFE is used more in architecture because it is easier to produce and is tough enough for most situations. PTFE is used more often in highly technical situations, such as cabling and industrial applications.

Modern uses of PTFE

Today, many stadiums around the world use PTFE as a roofing material. It has been part of FIFA World Cups in South Africa and Brazil. It covers multiple stadium courts at the U.S. Open in Flushing, New York. It is the roof for The O2 in London. PTFE is also part of some of the most cutting-edge football stadiums in the NFL, such as Cowboys Stadium in Arlington, Texas.

Outside of the sports world, PTFE is used in structures such as train station platforms, malls and airports to create roofs and canopies. Saudi Arabia’s Haj terminal at Jeddah Airport is one of the biggest tensile membrane structures in the world.

Those are just projects Birdair has worked on. Dozens of companies around the world use PTFE as a roofing material.

Beta cloth is no longer used in spacesuits, but it can still be found in space. It serves as the outer layer of multilayer insulation blankets, and is also used on interior and exterior surfaces of the international space station.

So the next time you go to a stadium with a retractable roof or a fabric canopy, you’re likely experiencing technology that came directly out of the moon landing.

Neil Armstrong - The effects of the Apollo program can be seen in many aspects of modern life. Sports stadiums and arenas around the world contain a piece of technology that was developed for spacesuits. PTFE (Teflon) was an outer protective layer of spacesuits that now serves as a durable, cost-effective roofing material. (Photo courtesy Getty Images)
Khalifa International Stadium - The stadium was initially constructed in 1976 in Doha, Qatar. It has hosted various events from the 1976 Gulf Cup to the 2006 Asian Games, and undergone renovations prior to each event. The addition of the roof was completed in 2017. This stadium is slated to be used in the 2022 FIFA World Cup in Qatar. (Photo by Supreme Committee for Delivery & Legacy/Qatar 2022 via Getty Images)
Arthur Ashe Stadium - The main stadium court at the USTA’s Billie Jean King National Tennis Center in Flushing, New York was constructed in 1997. It is the largest tennis-specific venue in the world. The retractable roof was completed in time for the 2016 US Open, and it allows the tournament to continue without rain delays that have caused issues in the past. (Photo by Timothy A. Clary/AFP/Getty Images)
Estadio Nacional - The stadium opened in 2013 for the 2014 FIFA World Cup in Brazil. It hosted seven World Cup matches including a quarterfinal match and the third place match. The stadium does not currently have a permanent tenant. (Photo by AMA/Corbis via Getty Images)
Nelson Mandela Bay Stadium - The stadium construction was completed in 2009. It was one of the stadiums used in the 2010 FIFA World Cup in South Africa, and hosted everything from group stage matches to the third place match. It’s currently home to both rugby and football clubs in Port Elizabeth. (Photo by Doug Pensinger/Getty Images)
Cowboys Stadium - The stadium was completed in 2009, and at the time it had the world’s longest retractable roof measuring 148,000 square feet. It also features one of the largest video screens in the world. Other than being home the NFL’s Dallas Cowboys, the stadium also hosts various NCAA and Texas UIL football games. (Photo by Brad Schloss/Icon SMI/Icon Sport Media via Getty Images)
Shanghai International Circuit - The Formula One track was completed in 2004, and played host to China’s first F1 race. It features PTFE canopies over the main grandstand. (Photo by Liu Jin/AFP/Getty Images)
NRG Stadium - When it was constructed in 2002, the stadium featured the first retractable roof in the NFL. Because it was constructed with translucent PTFE, it allowed the Houston Texans to use real grass instead of turf as a playing surface. (Photo by Brian Bahr/Getty Images)
Incheon Munhak Stadium - Incheon Munhak Stadium is a multipurpose sports complex in Incheon, South Korea, that was constructed in 2002. The shape of the roof replicates the masts and sails of ships crossing the sea. It was one of the new stadiums constructed for the 2002 World Cup in South Korea and Japan. (Photo by Chung Sung-Jun/Getty Images)
Veltins Arena - The stadium opened in 2001 as the new home for the football team FC Schalke 04. It hosted the 2004 UEFA Champions League Final and five matches in the 2006 World Cup in Germany. It features a teflon-coated fiberglass retractable roof, which spans the entire stadium. It was the first stadium in Germany that was completely privately financed. (Photo by Friedemann Vogel/Bongarts/Getty Images)
The O2 - The arena originally opened in 2000 as the Millennium Dome, but it closed a year later and re-opened in 2007 as the O2 Arena. It was host to gymnastics and basketball competition during the 2012 Olympic Games. It is a multipurpose indoor venue that has hosted everything from concerts to Premier League Darts to UFC fights to the ATP World Tour Finals. (Photo by Glyn Kirk/AFP/Getty Images)
Chase Field - The stadium in Downtown Phoenix was completed in 1998. It was the first stadium in MLB history to feature a retractable roof, grass playing field and air-conditioning combination. (Photo by Christian Petersen/Getty Images)

Sarah Farrell is a graduate student studying sports journalism at Arizona State University