Closest Approach Between Two Earth Satellites

Determine closest approach between two Earth satellites in circular or elliptical orbits.

This submission describes two MATLAB scripts that can be used to determine closest approach conditions between two satellites in circular or elliptical Earth orbits. Each script uses Brent’s one-dimensional minimization algorithm to calculate geometric close approach conditions. In the first script (ca2sats1) the orbits of both satellites are propagated using Kozai’s J2 method. In the second script (ca2sats2) the orbits of both satellites are propagated using an RKF78 numerical integration method which also includes the oblateness term J2 in the first-order orbital equations of motion.

These scripts create a simple text file of the results along with a tiff graphics file of the close approach distance as a function of the elapsed simulation time.