The application of periodic orbits to TOPEX mission design

This report develops analytic techniques for the application of periodic earth orbits to the design of the Ocean Topography Experiment (TOPEX) mission. The TOPEX orbit design space is described in terms of altitude and inclination. Periodic orbits that lie within that space are determined. Specific inclinations are determined that place a ground track grid node over a point on the earth at which a radar altimeter verification site is located. The number of orbit revolutions between the two ground tracks that cross at this grid node are also calculated. Then, periodic orbits that place a ground track directly over two different verification sites are calculated and displayed in the TOPEX orbit design space. The results are used to decide on a specific orbit altitude and inclination set that satisfies TOPEX requirements.