This paper addresses the problem of designing suitable satellite constellations for GPS Radio Occultation missions. Radio Occultation is a remote sensing technique for obtaining information, in real time, physical parameters of the atmosphere, such as density (and hence of temperature and pressure) and water vapor. When a radio signal from a transmitter on a GPS satellite passes through the limb of the atmosphere, the signal is delayed, and its path is bent by gradients in the refractivity field. If this signal is intercepted by a GPS receiver on another satellite, behind the Earth’s limb, then the time of receipt and the direction from which the signal is received are different from those that would have been obtained from an unrefracted path. For GPSRO missions, the signal bending (due to the atmosphere refraction) is measured by detecting Doppler shift. It is possible to retrieve information on temperature and pressure using an Abel transform for atmosphere altitudes below the ionosphere. The 2-D Lattice Flower Constellations theory is here applied to design constellations in order to maximize active time by providing global coverage with frequent measurements. Optimizations are performed using Genetic Algorithms to estimate constellation design parameters. Optimization is constrained by altitude range while orbit nodal precession is used to obtain global coverage.

Keywords: radio Occultation, GPS, 2-D lattice flower constellations