operated in polar orbits at altitudes of approximately 1100 km.
The objective of the TRANSIT system was to aid in the navigation of the U.S.
Navy’s Polaris submarine fleet. The first authorized civilian use of the system occurred
in 1967, and the surveying community quickly adopted the new technology,
finding it particularly useful for control surveying. Although these early instruments
were bulky and expensive, the observation sessions lengthy, and the accuracy
achieved moderate, the Doppler program was nevertheless an important breakthrough
in satellite positioning in general, and in surveying in particular.