The Department of Defense Navigation Satellite Timing and Ranging System (NAVSTAR) consists of twenty-four satellites. ________ are actively used and ________ are considered spares.
A) sixteen; eight
B) twenty-one; three
C) twenty; four
D) fifteen; nine

Question

Quizplus · Accepted Answer

NAVSTAR, commonly known as GPS, consists of twenty-four satellites, of which twenty-one are actively used for navigation and timing purposes, while three serve as spares to be activated if any of the active satellites fail or require maintenance.