Two reports propose the development of non-ablative aeroshells for braking of spacecraft entering the atmospheres of Earth, Mars, and other planets. The primary advantages of non-ablative aeroshells, relative to ablative aeroshells, results from reduced mass and increased aerodynamic stability of the aeroshell occasioned by elimination of the reactive ablative layer. A typical non-ablative aeroshell would comprise the following layers (in sequence from front to back): (1) a carbon-carbon face sheet coated with silicon carbide, (2) a hollow carbon-carbon structure like that of partitions in an egg crate, (3) a metal-coated carbon-carbon radiation plate, (4) a thermally insulating layer made of carbon aerogel, and (5) a carbon-carbon back plate.

This work was done by Gregory Hickey and Shyh-Shiuh Lih of Caltech for NASA's Jet Propulsion Laboratory.

NPO-20955

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Non-Ablative Aeroshells

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Overview

The document discusses the development and testing of non-ablative aeroshells for spacecraft entering the atmospheres of Earth, Mars, and other planets. Conducted by Gregory Hickey and Shyh-Shiuh Lih from Caltech for NASA’s Jet Propulsion Laboratory, the research highlights the advantages of non-ablative aeroshells over traditional ablative aeroshells. The primary benefits include reduced mass and enhanced aerodynamic stability due to the absence of a reactive ablative layer.

A typical non-ablative aeroshell is designed with several layers, arranged from front to back: a carbon-carbon face sheet coated with silicon carbide, a hollow carbon-carbon structure resembling an egg crate, a metal-coated carbon-carbon radiation plate, a thermally insulating layer made of carbon aerogel, and a carbon-carbon back plate. This layered structure is engineered to withstand the extreme conditions of atmospheric entry while maintaining structural integrity.

The document details experiments conducted in the NASA Ames Arc Jet Facility, where small models of the non-ablative aeroshell were tested to simulate the entry conditions expected for Mars. The results of these experiments were promising, demonstrating the effectiveness and survivability of the non-ablative aeroshell concept. Notably, the experiments revealed that the temperatures on the rear surfaces of the aeroshells did not exceed 100 °C, indicating that the design can effectively manage thermal loads during entry.

The research is part of a broader effort to improve spacecraft design for interplanetary missions, where efficient braking and thermal protection are critical for mission success. The findings suggest that non-ablative aeroshells could play a significant role in future space exploration, offering a lightweight and stable alternative to existing technologies.

The document also includes a notice regarding the sponsorship of the research by NASA and clarifies that references to specific commercial products do not imply endorsement by the U.S. Government or the Jet Propulsion Laboratory. For those interested in further details, copies of the reports titled “Non-Ablative Aeroshell” and “Investigation of the Survivability of a Non-Ablative Aeroshell Composed of Carbon/Carbon Composites and Carbon Aerogel” are available online through NASA's Technical Support Package.