Survivability and ground risk potential of screws and bolts of disintegrating spacecraft during uncontrolled re-entry

Spacecraft usually contain large amounts of screws and bolts in order to connect the elements of primary and secondary structure. These connecting parts are mainly made of stainless steel, a material with high melting temperature. The screws are often protected by the external structure against the high aerodynamic heat loads. During the destruction analysis for a re-entering spacecraft (e.g. with a code system like SCARAB) one usually concentrates on the heavy and larger parts of the main spacecraft structure. In order to assess the possible impact risk of the numerous screws and bolts a fast analysis method for these smaller parts seems necessary. HTG is therefore working on a fast analysis method based on the following simplifying assumptions: Flight dynamic based on Allen/Eggers method, heating based on Stanton number for integral heat transfer, infinite heat conduction within the body, averaged thermal data of materials. Based on these assumptions and an adequate non-dimensional analysis of the different process parameter general rules for the survivability can be deduced.