NASA has successfully developed a new and innovative Heatshield for Extreme Entry Environments Technology, or HEEET, which, at a Technology Readiness Level (TRL) of 6, is ready for use in Ice Giant missions. HEEET is not just a replacement for the legacy full-density carbon-phenolic (FDCP) material, which was used in NASA’s Pioneer-Venus and Galileo missions; it is also a more mass efficient and robust alternative, and a technology that has a sustainable manufacturing base. HEEET is a dual-layer, 3-dimensionally woven material. It has a dense outer layer, made of pure carbon fibers, that comes into contact with and protects against extreme entry environments. Below this layer is an integrally woven, lower density insulating layer, made of a blend of carbon and phenolic yarn, that reduces heat-conduction to the carrier structure. The present paper describes development of this material, its thermal, structural, and aerothermal testing, production of an engineering test unit at flight scale, and maturation for infusion into missions to various planetary destinations, with a focus on Ice Giant in situ missions. Finally, for representative entry velocities at Uranus and Neptune, and a range of entry masses and flight path angles, margined thicknesses of HEEET are computed. When the limits of heat fluxes and pressures that can be achieved in ground-test facilities, and loom limits, are imposed on these thickness estimates, it is shown that several atmospheric entry missions are possible at the two destinations.

中文翻译：

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冰巨行星探测任务的进入系统技术准备情况

NASA 已成功开发出一种全新的创新型极端进入环境技术（HEEET）隔热罩，其技术准备水平 (TRL) 为 6，可用于冰巨人任务。HEEET 不仅是 NASA 的先驱者-金星和伽利略任务中使用的传统全密度碳酚醛 (FDCP) 材料的替代品；它也是一种更高效、更强大的替代品，以及一种具有可持续制造基础的技术。HEEET 是一种双层 3 维编织材料。它有一个致密的外层，由纯碳纤维制成，可以接触并防止极端进入环境。该层下方是整体编织的低密度绝缘层，由碳和酚醛纱线的混合物制成，可减少对载体结构的热传导。本论文描述了这种材料的开发、热、结构和空气热测试，飞行规模的工程测试单元的生产，以及注入到各种行星目的地的任务的成熟度，重点是冰巨人的原位任务。最后，对于天王星和海王星的代表性进入速度，以及一系列进入质量和飞行路径角，计算 HEEET 的边缘厚度。当在地面测试设施中可以实现的热通量和压力限制以及织机限制强加于这些厚度估计值时，表明在这两个目的地可能进行多个大气进入任务。并成熟以注入到各种行星目的地的任务中，重点是冰巨人的原地任务。最后，对于天王星和海王星的代表性进入速度，以及一系列进入质量和飞行路径角，计算 HEEET 的边缘厚度。当在地面测试设施中可以实现的热通量和压力限制以及织机限制强加于这些厚度估计值时，表明在这两个目的地可能进行多个大气进入任务。并成熟以注入到各种行星目的地的任务中，重点是冰巨人的原地任务。最后，对于天王星和海王星的代表性进入速度，以及一系列进入质量和飞行路径角，计算 HEEET 的边缘厚度。当在地面测试设施中可以实现的热通量和压力限制以及织机限制强加于这些厚度估计值时，表明在这两个目的地可能进行多个大气进入任务。