For most of us it's hard to imagine that something that is inflated can survive the high heat and friction of space travel, especially atmospheric entry.
But a group of NASA engineers, primarily based at NASA's Langley Research Center, have been working to develop inflatable spacecraft aeroshell technology for more than a decade.
"We have been eating, sleeping, dreaming this technology — in my case for six years," said Anthony Calomino during a peer review of the Hypersonic Inflatable Aerodynamic Decelerator project. The project, which was part of the Space Technology Mission Directorate's Game Changing Development Program, is wrapping up after three years.
Some of the research and team are transitioning to the Terrestrial HIAD — Hypersonic Inflatable Aerodynamic Decelerator - Orbital Reentry, or THOR, flight test. That test is a Technology Demonstration Mission and also part of the Space Technology Mission Directorate.
Before HIAD moved forward the team wanted an outside assessment of its potential. "We [who have worked on HIAD] have a certain familiarity with it," said Calomino. We wanted to have an independent group — a fresh set of eyes — looking at this technology."
The five member peer review panel spent two days at NASA Langley, in person and by web conference, listening to the progress researchers have made in developing the key technologies needed for an inflatable reentry vehicle — the inflatable structure and flexible thermal protection system (TPS). On the panel were two members from academia, one from NASA Headquarters, one from NASA's Marshall Space Flight Center and another from NASA's Ames Research Center. Their expertise ranged from aeronautics and astronautics to systems and aerospace engineering to human exploration and exploration architecture to atmospheric entry, descent and landing.
They listened as one of the most passionate champions of Hypersonic Inflatable Aerodynamic Decelerators, Neil Cheatwood, took them through some of the background behind the research.
"This idea has actually been around since the 1960s," said Cheatwood. "But now we have materials that can withstand higher temperatures."
"We've made great strides with this technology," added Cheatwood. "I think HIAD is the most important entry, descent and landing technology under development by the Agency [especially for Mars]. The issue with Mars is that it has a poor excuse for an atmosphere, but you can't ignore it."
Cheatwood pointed to the successful Inflatable Reentry Vehicle Experiment (IRVE-3) flight test launched from NASA's Wallops Flight Facility on a sounding rocket in 2012. "IRVE-3 was the Michael Jackson of HIAD. It’s gotten all the attention," said Cheatwood. "But there’s a lot more talent in the Jackson family, and a lot more to the HIAD project. During this review, you'll also hear about Janet, Jermaine, Latoya, and Tito"
"IRVE-3 was a big success for space technology," added Cheatwood. "But we have now taken HIAD technology about as far as we can with sounding rockets. We have to go beyond that."
IRVE-3 was a three-meter or about 10-foot test article that, when inflated, looked like a child's stacking ring toy composed of giant braided, reinforced, high-tech fabric hoops lashed together — then covered by a thermal blanket made up of layers of heat resistant materials. The team worked to develop technologies that could allow the aeroshell to be bigger — knowing one would be needed to carry more cargo and perhaps even people to Mars.
They collaborated with universities and industry and did wind tunnel tests at NASA facilities and others across the country. "We really had goals," said Calomino. "The tech development effort was almost a slam dunk for first generation performance. Then in fiscal year 2014 we started to focus on second generation — to increase the peak heating and integrated heat load [capability]."
"I can't say enough about what we have accomplished," said Cheatwood. "What we have done with flexible TPS is amazing." But Cheatwood said more needs to be done before the technology could be used to get to Mars — larger scale articles need to be developed and tested. The THOR flight test in 2016 plans to use existing hardware that includes an aeroshell only slightly larger than IRVE-3 — about 12 feet in diameter.
The peer review panel plans to issue a final report of their findings, but members did offer a few opinions. "The collaborations with industry and academia are critical, said Juan Alonso of Stanford University. "We encourage you to continue that. You achieved a lot. "Kudos to everyone."
"You guys had a really tough task," said Les Alexander, an exploration architecture expert from NASA Marshall. "Going forward it needs to be a more integrated effort."
Christopher Moore, representing human exploration at NASA HQ, told the team, "It's important to show traceability of human exploration to your efforts. You have to fly something that works and you're on the path to do it."
NASA Langley Research Center