The Close Approach Tool is a fully integrated capability available for STK that enables you to analyze and assess the potential for close proximity between a satellite and other objects in space. As the Iridium/Cosmos collision in 2009 showed, analysis of close approaches has become a significant concern in mission analysis. Using Close Approach, you can search an external file containing thousands of satellites for those that meet a minimum range tolerance. The file must contain GP data for use with the SGP4 propagator. Example files include TLE files or files containing OMM data formatted in XML, KVN, or CSV formats. Once you specify the range tolerance allowed between a given satellite and other objects, the Close Approach Tool quickly analyzes the information against all objects in the external file.