Design and maintenance of InSAR configuration for digital elevation measurement under J₂ perturbation

The present paper proposes a formation configuration for three spacecrafts to perform the digital elevation model (abbr. DEM) for the distributed spacecraft interferometric synthetic aperture radar (InSAR). The configuration is optimized analytically to possess the best compatibility with J₂ relative invariant orbits. The relative orbital elements are utilized to design the optimal orbit by reducing the drift in the along-track direction for maintaining the baseline. The baseline is expressed as the function of the relative orbital elements, where the baseline along across-track direction has the law of trigonometric function. This paper proposes the method to form the relative J₂ relative invariant configuration and generate the nearly-constant across-track baseline via only three spacecrafts rather than the unpractical infinite numerical numbers in theory. Simulation results validate the approach presented in this paper.