Detect and assess potential collisions in space.

STK Conjunction Analysis Tools is an add-on module for Systems Tool Kit (STK) that comprises four collision-threat analysis tools:

  • The Close Approach tool detects conjunction events for a single primary satellite with any set of space objects defined by a TLE file.
  • The Advanced CAT (AdvCAT) tool detects conjunctions for a set of primary objects against a set of secondary objects, where proximity is measured as the distance between threat volumes.
  • The Launch Window Analysis tool determines the blackout times in a launch time window — wherein a conjunction with a secondary object would occur.
  • The LaserCAT tool determines the blackout times within a firing time window of a ground-based laser.
Image from STK CAT, C-5 Galaxy

Use Cases

  • Detecting close approaches to a satellite of interest.
  • Computing threat volumes for groups of objects.
  • Assessing the potential for an unintended illumination of a satellite.
  • Evaluating a launch window.


  • Uses the NORAD TLE database of more than 15,000 objects.  
  • 3D visualization of error volumes.
  • High-fidelity integrated ephemeris supported for both primary and secondary objects.
  • Computes probability metrics, appropriate for both short and long encounters.
  • Supports scripted automation of data updates, computations, and reporting.