Image: Aviation Week Network
Happy Saturday! Here is an interesting graphic timeline of more than 50 years of GPS history by Aviation Week.
Here’s another fun fact. This timeline begins with the launch of Transit in April of 1960, a joint project of DARPA and Johns Hopkins APL. But the science goes back even further to the launch of Sputnik in October 1957.
Two bright guys at Johns Hopkins were fascinated listening to Sputnik’s beep, beep, beep grow quicker as it approached the zenith, and slower as it receded. They reasoned they could figure out its orbit using the doppler effect. Then they realized if the orbit was know, they could invert the equations and figure out where they were. Check out this first persons account by William H. Guier and George C. Weiffenbach here.
GPS is not doppler navigation system, but Transist, its precursor was.
Graham Warwick November 16, 2023
Now in its seventh iteration of spacecraft design, GPS remains the most used and relied upon among the several systems now providing space-based position, navigation and timing.