Projectiles as large as space vehicle and as small as cannon projectile have some way to communicate with their ground station or launcher. Presented is a simple way to generate a modified polar coordinate in space. A projectile can sense its position in the spatial coordinate very easily.
"Reticule Scanned And Pulse Modulated Laser Beam Spatial Coordinate System Design", Proc. SPIE 0813, Optics and the Information Age, (1 January 1987); doi: 10.1117/12.967171; https://doi.org/10.1117/12.967171