“We were interested in looking at more robust systems,” Camarda told ARS. “The first one I ever tested was actually an all-metal tail wing leading edge, and it used heat pipes, and it was built by McDonnell Douglas. It was a competitor to the passive carbon-carbon, passive leading edge system.”
Ultimately, NASA went with a reinforced carbon-carbon heat shield for the shuttle’s wing and nosecone leading edges, while the shuttle’s belly was protected by ceramic tiles. It was one of these reinforced carbon-carbon panels that broke on the space shuttle Columbia when it was hit by a piece of foam from the shuttle’s external fuel tank during launch in January 2003. The damage wasn’t discovered until the shuttle broke apart during reentry 16 days later, killing all seven astronauts on board.
Camarda flew as a mission specialist on the next shuttle flight in 2005 after NASA developed techniques to repair a damaged heat shield in space.
“I did very early radiant heating testing and hypersonic wind tunnel testing of this all-metal wing leading edge, and it would basically take heat from the bottom surface and basically pump it up to the top surface, so the entire wing leading edge glowed at almost the same temperature because it was such an efficient two-phase heat transfer,” said Kamarda.
Camard’s work at NASA’s Langley Research Center’s Thermal Structures Branch was limited to ground-based testing in high-temperature wind tunnels. His designs never flew on the space shuttle.
“When I saw [SpaceX] testing different types of metallic heat shields, the guys… at my old branch, everyone was like, ‘Wow, this is phenomenal! We wish we were young again, and NASA was this alive, you know?’ But unfortunately, we didn’t see it.”
Camarda said NASA’s approach to testing is much different from how SpaceX handles things.
NASA astronaut Chris Ferguson, STS-135 commander, right, and pilot Doug Hurley, left, inspect the orbiter’s thermal tiles after the space shuttle Atlantis lifted off from Kennedy Space Center in Florida, completing STS-135, the final mission of NASA’s Shuttle program, Thursday, July 21, 2011.
Credit: Smiley N. Pool/Houston Chronicle via Getty Images
“It’s amazing what these guys are doing, and they’re doing it so fast, and they’re testing a lot of things at once,” Kamarda said. “I almost wonder if this is a smart thing to do. He’s failing big. Is his vehicle cheap enough that he could use it as a hypersonic flight test? Is it so cheap that he could afford to do it?
“We had such tight budgets at the research center that we had to fix and salvage every little thing,” Kamarda said. “So, we would take a building block approach and never be brave enough to do this very large test with several hundred changes. It’s crazy.”
The elephant in the room
SpaceX has blamed fuel leaks and engine malfunctions for Starship failures this year. In addition to the program’s flight failures, another Starship exploded during a ground test in June when a nitrogen tank failed.
Elon Musk didn’t mention any of this when he appeared for about 20 minutes on a SpaceX live webcast on Monday. Musk had originally planned to give a “technical update” on the X Spaces platform on Sunday. In that format, Musk was expected to answer questions from members of the space press corps and space enthusiasts hungry for details about not only the promise of a rocket as potentially revolutionary as the Starship, but also the hurdles SpaceX will have to overcome to make it a reality.
But SpaceX canceled the event without explanation. Instead, Musk appeared on SpaceX’s official pre-launch livestream. Most of the discussion centered not on detailed technical updates but on familiar Musk talking points: making humanity a multi-planet species and why a rocket like the Asteroid is needed to make that happen.
After the heat shield, one of the next big test goals for the Starship program will be in-orbit refueling. It’s a crucial prerequisite for any Starship that ventures into deep space. SpaceX’s gigantic rocket is designed to carry up to 150 tons of cargo to low-Earth orbit, but it can’t go any further without refueling its cryogenic propellant tanks.
