Minuteman gravity modeling

Accurate targeting of inertially-guided intercontinental ballistic missiles requires simulating with a high degree of fidelity the gravitational force acting on the missile. An accurate representation is particularly important in the first portion of flight where target miss sensitivity to navigation error is largest. The paper describes the point mass Launch Region Gravity Model (LRGM) representation developed for Minuteman targeting and addresses a number of the considerations involved in selecting this model form. Illustrated are the four point mass grids selected to provide increasingly greater model detail near the launch site. The data base employed for model development is described. A chronology of past and projected model accuracy improvements is presented.