It was just about three years when several satellites were placed in orbit to have a Solar Positioning System (SPS) for our solar system and was used for interplanetary operations with very good success. The Sun was considered a the center of the SPS. The paths of all the planets were properly mapped with reference to the Sun in the subsequent three year period. For this, the SPS coordinates were used. There was tremendous excitement when the SPS was launched. The chief object of the SPS was to facilitate mobility in our solar system. Man/women were no longer confined to Earth and now was slowly occupying the solar system.
The establishment of SPS was a catalyst to several missions being made by several countries in a very short period of time.
The SPS was a polar coordinate system (also called as the radial system) and not based on the cartesian coordinate system at was the earth. The vector joining the Sun and the Earth on 1st January was the 0,0. Any angle towards the north was considered positive in the vertical plane. All clockwise angles were also considered as positive in the horizontal plane. The horizontal plane is defined as the plane including the 0,0 vector and the equator. The vertical plane is perpendicular to the horizontal plane.
Thus the SPS gave the straight distance of the object from the Sun and the angles the line made with the horizontal and the vertical plane.
However, getting the coordinate was not as simple as the GPS did on Earth. This was because it took considerable time (maximum of 15 minutes) for the signals to reach the SPS locator. Thus the locators provided an instantaneous tentative position and the same was confirmed with changes after a while.