Precision Orbit Determination
6
H|0|gpsa|GPS receiver|564|575|
G|0|doris|DORIS|229|233|
G|0|slr|SLR|221|223|
G|0|3cm|3 centimeters|868|880|
G|0|radial|radial position|820|834|
H|0|locate|location of the satellite in its orbit|112|149|
    The Precision Orbit Determination and Verification Team is responsible for establishing very precisely the location of the satellite in its orbit, and verifying the accuracy of their calculations. 
    Data from the SLR and DORIS systems are used to determine the orbit of TOPEX/Poseidon. Together these systems provide all-weather, global tracking of the satellite. There are however, some limitations in land-based systems. 
    To develop more accurate and less expensive methods of calculating orbits, the project installed a Global Positioning System or GPS receiver on the spacecraft as a flight experiment. 
    The experiment proved a great success. During testing the GPS receiver simultaneously tracked signals from as many as 8 of the 21 GPS satellites that orbit the earth and provided the spacecraft's radial position with an accuracy of better than 3 centimeters. 
