Space based radar constellation optimization

Research was conducted to develop optimal orbital constellations for a representative space based radar (SBR) concept. Many recent SBR designs are based on a multi-mode radar capable of a variety of missions such as airborne moving target indication (AMTI), ground moving target indication (GMTI), and synthetic aperture radar (SAR) imagery. This broad surveillance scope provides greater flexibility to the theater commander while providing and maintaining global access. The analysis was conducted on circular low earth orbits, at 926 km altitude, in order to avoid the Earth´s radiation belts. Coverage computations were based solely on geometrical configurations and thus did not include processing effects such as weather, terrain features, or stealthy targets. Based on a representative phased array antenna design, the ground sensor pattern approximates a butterfly shape, enabling the sensor to look generally to the left and right of its flight path, but neither ahead nor behind. In addition, the radar is not able to see in a small area below itself. The unusual shape of the sensor footprint, combined with widely varying constraints for the separate missions, created challenging optimization problems. Coverage computations were conducted using both standard commercial software packages and custom software