Abstract: A reusable, externally applied thermal protection system is disclosed and functions by utilizing shell tile structure 10 which effectively separates its primary functions as an insulator and load absorber. Tile 10 consists of structurally strong upper and lower metallic shells 12,16 manufactured from materials meeting the thermal and structural requirements incident to tile 10 placement on the spacecraft. A lightweight, high temperature package of insulation 26 is utilized in upper shell 12, while a lightweight, low temperature insulation 28 is utilized in lower shell 16. Assembly of tile 10, which is facilitated by self-locking mechanism 20, may occur subsequent to installation of lower shell 16 on the spacecraft structural skin 30.

Abstract: A spiral wound retaining ring 10 with angled ends 214 and 216 is disclosed. The ring is crimped 220 at the same angle as the ring ends to maintain a constant thickness dimension. The angling of the ends of the ring and crimp allow the ends to be positioned closer together while maintaining enough clearance to enable insertion and removal of the ring. By reducing the separation distance between the ends a stronger ring results since the double layer area of the ring is maximized.