Determining Probability Upper Bounds for NEO Close Approaches

Collision probability analysis is accomplished by combining covariances and physical object dimensions at the point of closest approach. The resulting covariance ellipsoid and hardbody are projected into the plane perpendicular to relative velocity. Collision potential is determined from the object footprint on the projected covariance ellipse. This paper shows how to calculate the upper bounds of probability by determining the worst possible covariance parameters and orientation. These methods can be used as a simple pre-filter or to determine worstcase scenarios when the actual covariances are not known.