Earth orbits and satellite coverage display in 3D on your laptop.
SaVi - simulate Starlink, Iridium, Globalstar, O3b, GPS, Galileo and other satellite constellations, modify them, or design your own. Requires Tcl/Tk and Unix libraries; 3D viewing option requires Geomview running on X Window.
The PDL module gives standard perl the ability to COMPACTLY store and SPEEDILY manipulate the large N-dimensional data sets that are the bread and butter of scientific computing.