The first experimental GPS satellite reaches orbit

NAVSTAR 1 wasn't meant to provide navigation service to anyone. It was a test satellite, part of a small experimental group called Block I, built to answer engineering questions before the government committed to building a full operational fleet: would the atomic clocks stay accurate enough in orbit, could ground control track and correct the satellites reliably, and would receiver designs actually work with real signals from space rather than simulations. Every one of those questions had to be answered before anyone would fund the roughly 24-satellite constellation the finished system would eventually need.