The very first satellite system launched by the United States was called Transit. The satellite Transit was tested by the United States Navy in 1960.
You probably ask yourself, how many satellites are needed?
Well let me tell you that, only five satellites are needed for ships to determine their position at the seas. This can be done once every hour with the help of the satellites that are orbiting the planet.
However, Transit was quickly succeeded. Back in 1967, the Timation satellite demonstrated a highly accurate atomic clocks that can be operated in the space.
History of GPS shows quick development for military purposes. So, between 1978 and 1985 with a total of 11 “Block” satellites being launched, the development of GPS started.
The upgrade of the GPS was delayed by NASA. The reason was their space shuttle SS Challenger which had experienced a disaster in 1986.
