Determination of atmospheric density using a space-launched projectile

A method that provides advance information about unpredictable atmospheric density dispersions that must be accommodated during random operations of aeroassisted orbital transfer vehicles (AOTVs) is proposed. The principal feature is that a test or "scout" projectile precedes the AOTV through the same region of the atmosphere as that of the predicted transatmospheric flight trajectory. The time lag between passage of the projectile and the AOTV can be adjusted to only that time necessary to implement required guidance, navigation, and control corrections. The various strategies available to control the projectile's flight characteristics are analyzed in detail. The results are correlated with aerothermodynamic heating and materials requirements to ensure the survival of the projectile and, consequently, the capability of the AOTV to navigate a variable upper atmosphere within specified limits.