Author: Mika Takahashi, Technology Analyst at IDTechEx
On April 22nd, SpaceX's Bandwagon-3 rideshare mission took off from Cape Canaveral. Alongside the normal payload of satellites, there was a capsule from a German space start-up – Phoenix 1. This was the inaugural payload of ATMOS Space GmbH, and the first orbital test of its inflatable aerodynamic decelerator (IAD).
To re-enter from low-Earth orbit, most spacecraft either use a tile-based system or an ablator. Tile-based heat shields, such as those used in the Space Shuttle, Sierra Dream Chaser, X-37, and SpaceX Starship, utilize low-conductivity materials with high surface emissivity to protect spacecraft during re-entry. Ablators opt for a different approach, 'pyrolyzing' under re-entry and converting excess heat into material consumption, essentially the heat shield burns up and 'wicks' away heat from the spacecraft. Both of these families of thermal protection systems (TPS) are covered in-depth in IDTechEx's recent report, “Heat Shields & Thermal Protection Systems for Spacecraft 2025-2035: Technologies and Market Outlook“.
The maximum size of most TPS is limited by the rocket payload fairing. IADs change the game by utilizing folded designs to allow compact storage during launch, but can expand significantly before re-entry. This expansion in surface area fundamentally alters the aerothermodynamics of re-entry, by reducing the ballistic coefficient, the peak heating, total heat load, and mechanical load can be lowered, allowing for a gentler re-entry. IADs have been theoretically explored for decades; however, it is only in the last few years that research efforts have begun to bear fruit.
Phoenix differentiates itself from NASA and LOFTID
NASA tested its own IAD in 2022, with LOFTID (Low-Earth Orbital Flight Test of an Inflatable Decelerator). This test illustrated one of the biggest challenges for IADs – how to inflate these large devices in space. LOFTID used a nitrogen gas inflation system, which, when accounting for tanks, gas, and regulators, weighed 135kg. With spaceflight, weight is everything, so for IADs to be competitive versus other TPS, this weight penalty needs to be drastically reduced. ATMOS claims to have cracked an alternative approach that bypasses the need to carry pressurized tanks. They are inflating their shield using gas from the boundary layer in the atmosphere, using ceramic matrix composite air inlets.
New design allows opportunities for new materials
The materials for traditional TPS (such as carbon-carbons, silica tiles, phenolic and silicon resins) are broken down in-depth in IDTechEx's “Heat Shields & Thermal Protection Systems for Spacecraft 2025-2035: Technologies and Market Outlook” report, with quantitative benchmarking data and manufacturing considerations. IADs could offer radically new material opportunities, due to the significantly different requirements vs a rigid heat shield. IADs have unique design constraints, and IDTechEx's report highlights the role of:
- Aerogels for lightweight thermal insulation
- Ceramic Fibres for outer layer temperature protection
- Laminated Gas Barriers
- Braided structural fabrics
The report also looks at the specific requirements of thermal conductivity and gives examples of suppliers/products used in IADs to date.
Inflatable heat shields offer new material opportunities and work by reducing the ballistic coefficient for a more gentle (by spacecraft standards) re-entry. Source: IDTechEx
Phoenix 1 was viewed as a success despite lack of capsule recovery
The Phoenix 1 test resulted in a splashdown over 2,000km off the coast of South America, so recovery was not an option. Nevertheless, ATMOS announced that it had successfully recorded all critical mission and payload data. It is unclear what state the Phoenix 1 heatshield was in upon impact with the ocean, but ATMOS claims that its approach is to “rapidly iterate and update”, with plans already in place for a Phoenix 2 with a propulsion system for trajectory control. This approach of rapid development echoes the SpaceX mentality, where failures are seen as opportunities to improve, prioritizing real-mission time and data collection opportunities. IADs could also dramatically impact:
- Launch Economics (reusable upper stages)
- Planetary Exploration (high-mass Mars landers)
- Defense Logistics (rapid orbital cargo delivery)
IAD roadmap
Compared with established TPS, IADs are at an early stage of development. IDTechEx's “Heat Shields & Thermal Protection Systems for Spacecraft 2025-2035: Technologies and Market Outlook” report covers how PICA and tiled heat shields have been providing the bulk of LEO return mission capabilities for decades. However, Phoenix's test highlights several key points:
- Commercial Development of Space Technologies is Accelerating: Although NASA was the first organization to test an IAD in 2022, the fact that a European start-up has developed a differentiated technology and tested it in orbital conditions within 4 years of founding emphasizes the shifting landscape of the space industry, and the speed at which these changes are occurring. Cutting-edge space technology is no longer exclusively the domain of governmental agencies.
- IADs beginning to enter the TPS space: At a time when demand for space travel (for microgravity research, in-orbit manufacturing, satellites, and defense applications) is booming, IADs may soon offer an alternative to established tile and ablative TPS. There are still many hurdles to be overcome, but it is realistic to expect that by the end of the decade, some commercial missions will be operated with IADs.
“Heat Shields & Thermal Protection Systems for Spacecraft 2025-2035: Technologies and Market Outlook” also breaks down some of the remaining challenges for IADs, as well as examining other players exploring their use. For example, ULA (United Launch Alliance) is exploring stage 1 booster recovery using a variant of NASA's LOFTID. Mechanically deployed aerodynamic decelerators (MDADs), an alternative approach to increasing the re-entry surface area. IDTechEx's granular report offers a chance to stay informed in this rapidly evolving market.
To find out more about this IDTechEx report, including downloadable sample pages, please visit www.IDTechEx.com/TPSSpacecraft.
For the full portfolio of market research available from IDTechEx, please see www.IDTechEx.com.
