"With a combination of large ground-based FORTRAN programs and small spacecraft-based assembly language programs, [Real Programmers] are able to do incredible feats of navigation and improvisation -- hitting ten-kilometer wide windows at Saturn after six years in space, repairing or bypassing damaged sensor platforms, radios, and batteries. Allegedly, one Real Programmer managed to tuck a pattern-matching program into a few hundred bytes of unused memory in a Voyager spacecraft that searched for, located, and photographed a new moon of Jupiter.
The current plan for the Galileo spacecraft is to use a gravity assist trajectory past Mars on the way to Jupiter. This trajectory passes within 80+/-3 kilometers of the surface of Mars. Nobody is going to trust a PASCAL program (or a PASCAL programmer) for navigation to these tolerances."