Old Space Shuttles Need Love Too

Pathfinder Gets a Major Makeover at Alabama’s U.S. Space and Rocket Center

20 June 2023

HUNTSVILLE, AL—When NASA retired its famous space shuttle fleet in 2011, the country’s manned space exploration program took a break. It was the end of an era marked by bold exploration, amazing discoveries, stretching the boundaries of our human grasp, and tragic loss of human life. While NASA went about testing the next generation of rockets for a future fleet of manned space vehicles, the question was what to do with the iconic space shuttle fleet?

There were seven space shuttles, six of which were operational, plus one simulator the same size, weight, and shape of a space shuttle orbiter designed to test the original 747-launch system. Four flew in space: Atlantis, Discovery, Endeavour, and Enterprise, and Columbia which made it into space, but disintegrated upon reentry. Challenger disintegrated 73 seconds after lift-off. The simulator was built in 1977 and eventually named Pathfinder.

Upon retirement NASA sent the shuttles off to all corners of the US: Atlantis to Kennedy Space Center in Florida, Discovery to Smithsonian National Air and Space Museum’s annex in Virginia, Endeavour to the California Science Center, and Enterprise sits at the Intrepid Sea, Air & Space Museum in New York City. Pathfinder first made its way to Tokyo before landing at the U.S. Space and Rocket Center in Huntsville, Alabama in 1988 where it sits today.

In the late 1970s and early 80s, when NASA and Rockwell designed the original external tank (ET) for the shuttle program to hold the liquid hydrogen fuel and liquid oxygen oxidizer, it needed a supplier of high-performance insulation to withstand pressure and heat from the solid rocket boosters helping lift the shuttle into space. They chose NCFI Polyurethanes of Mount Airy, North Carolina to formulate a spray-applied polyurethane foam insulation specifically for the U.S. shuttle program. NCFI’s foam insulation is what gives the ET its iconic orange color. While the ET was redesigned a number of times by Martin Marietta and later Lockheed, the only NASA-ULA (United Launch Alliance) certified partner for spray foam insulation is NCFI.

Back to Pathfinder sitting out exposed to the elements at the U.S. Space and Rocket Center. When the curators of the museum determined after 40 years the space shuttle display needed a full multi-million-dollar restoration, and via a grant from the National Park Service’s Saving America’s Treasures program and donations, they started work in late 2020. To ensure the shuttle system would keep as close to the original as possible, they called NASA who in turn called NCFI.

“One of our contacts at NASA called to talk about how to go about restoring the foam insulation on the external tank of Pathfinder,” says Mitch Clifton, EVP at NCFI. “It had been sitting exposed since 1984, and recoated in the 1990s, so the whole system needed to be replaced. Since we are the only certified NASA and ULA spray foam insulation partner, they wanted to know if we would supply foam insulation and recommend an applicator.” Clifton says he consulted account manager and engineer Richard Rose, Ph.D. Rose recommended a customer in Shelly, Idaho — a family-owned insulation contractor called AAA Urethane.

In 2008, the U.S. Space and Rocket Center did a round of repairs in situ to the steel structure holding the full space shuttle assembly — the orbiter, ET, and rocket boosters. In February 2021, the orbiter, or the craft section most refer to as the “space shuttle,” minus the tail and wing sections, was lowered from its mount atop the ET for the first time since 1988. This left the ET bare and ready to be stripped of the old insulation, restored, and new foam and coating applied.

Bryce Andrews and Kevin Andrews, owners of AAA Urethane, came from Idaho to Alabama to start work on the ET — which had actually launched a shuttle into space and been recovered — in September 2021 by testing for tear-off of the old foam and coatings. “We had to get licensed in Alabama, then we went through the public bid stage, but the project and process were so complicated and intricate, we were the only ones who could meet the requirements. Next came the second round of paperwork, testing, and documentation before we ever saw the external tank. We had a lot of help getting through it from the director of procurement at the U.S. Space and Rocket Center.”

According to Bryce Andrews the first real work began when a company out of Texas stripped off the old foam and coatings with a media that consisted of flexible foam imbedded with crushed walnut shells blown with high pressure air. Once the foam and coating were gone, they had to wrap the two newly painted rocket boosters in 4 mil. plastic, then prime the tank. Andrews says, “The weather in Huntsville in February determined our timeline. Lots of rain and wind; neither of which is conducive to applying foam and coatings, nor to being 70 feet off the ground.”

AAA Urethane chose a 2.8 lb. closed-cell foam insulation from NCFI. Andrews says, “It’s an ideal SPF when you add a good UV resistant coating. There is no coincidence NCFI foam is the only foam insulation used by NASA and the ULA.” They followed up with 40 mils of polyurea fast-set coating and 40 mils of aliphatic urethane for a total mil thickness of 80 dry mils provided by a coatings manufacturer recommended by NCFI.

Andrews says, “We had to dye the aliphatic urethane coating to match the yellow-orange look of medium-aged uncoated foam used by NASA on shuttle launches. We had a lot of back and forth about how to present the foam on the tank. In the end we created the closest shade we could to what was on that tank when it rolled out of the warehouse to launch a space shuttle.”

Kevin Andrews says NASA used to spray the tanks by standing them on the end vertically and using robots to spray them. “As that is not an option for us, we brought in boom lifts and scissor lifts and sprayed it by hand. Working around wind, rain, and tornado warnings, we were able to finish the work in 21 days while the museum remained open to the public. The wind was the enemy, so we had to be careful controlling overspray, but we took our time and were meticulous about it.”

Clifton says seeing one of the space shuttles look new again is a thrill for people at NCFI. “Our company turns 60 next year, and our 40-year partnership with NASA has been a big part of our culture. The space shuttle chapter of our NASA story is a source of immense pride for our associates in NC and Houston, Texas. We now work with private space companies, and we’re already working on the newer NASA rocket programs and unmanned craft with the goal of turning them into a new phase of manned space exploration, so we’ll continue being a partner in our country’s space program. To be honest, though, our hearts will probably always belong to old space shuttles like Pathfinder.”