Woven Thermal Protection System

Going farther, faster and hotter in space means innovating how NASA constructs the materials used for heat shields. For HEEET, this results in the use of dual-layer, three-dimensional, woven materials capable of reducing entry loads and lowering the mass of heat shields by up to 40%. The outer layer, exposed to a harsh environment during atmospheric entry, consists of a fine, dense weave using carbon yarns. The inner layer is a low-density, thermally insulating weave consisting of a special yarn that blends together carbon and flame-resistant phenolic materials. Heat shield designers can adjust the thickness of the inner layer to keep temperatures low enough to protect against the extreme heat of entering an atmosphere, allowing the heat shield to be bonded onto the structure of the spacecraft itself. The outer and inner layers are woven together in three dimensions, mechanically interlocking them so they cannot come apart. To create this material, manufacturers employ a 3-D weaving process that is similar to that used to weave a 2-D cloth or a rug. For HEEET, computer-controlled looms precisely place the yarns to make this kind of complex three-dimensional weave possible. The materials are woven into flat panels that are formed to fit the shape of the capsule forebody. Then the panels are infused with a low-density version of phenolic material that holds the yarns together and fills the space between them in the weave, resulting in a sturdy final structure. As the size of each finished piece of HEEET material is limited by the size of the loom used to weave the material, the HEEET heat shield is made out of a series of tiles. At the points where each tile connects, the gaps are filled through inventive designs to bond the tiles together. NASA's Heatshield for Extreme Entry Environment Technology (HEEET) is a 3-D woven heatshield design made to efficiently reject extreme heating during space vehicle entry into a planetary atmosphere. HEEET is a system to protect probe or scientific payload. The technology presents a revolutionary approach to the designing and manufacturing of TPS materials. The woven TPS configuration, in both its material composition and architecture, can be adapted to cover a range of space vehicle and environment choices including vehicle entry velocity, vehicle entry flight path angle, initial time interval for vehicle deceleration, vehicle nose shape (e.g., blunt or wedge), initial entry pressure, heating rate (variable with time), cumulative heat load, time interval for heating, and relevant atmospheric characteristics, among other attributes.