Figure 2.
A line chart presents the total number of G P S satellites in orbit from 1978 to 2015 alongside the number of satellites by block type over the same period. The left vertical axis shows the total number of G P S satellites in orbit, increasing from about 4 in 1978 to a peak of around 36 by approximately 2010, before slightly decreasing to about 33 by 2015. The right vertical axis shows the number of satellites in orbit by block type. Early years are dominated by Block 1 satellites, which rise through the early 1980s and then decline to zero by the mid 1990s. Block 2 satellites increase during the late 1980s and early 1990s and gradually decline after 2000. Block 2 A satellites rise sharply during the early 1990s, peak in the late 1990s, and then steadily decline to near zero by around 2015. Block 2 R and Block 2 R M satellites appear from the late 1990s onward with moderate counts through the 2000s. Block 2 F satellites begin appearing after 2010 and increase toward the end of the timeline.Timeline of GPS Satellites in Orbit
Source(s):GPS World (2016)