Constellation Design and Analysis for Spaceborne DInSAR Mapping in Mid Inclination Orbits: the IRIDE NIMBUS Mission

The IRIDE constellation is an ambitious Italian space program that, comprising a series of small satellite subconstellations exploiting a wide range of remote sensing technologies, will support the national authorities in their analysis and monitoring activities, with a focus on the Italian territory mapping.This paper analyses the NIMBUS X-Band Synthetic Aperture Radar (SAR) IRIDE sub-constellation, exploring potential orbital configurations beyond the more conventional and widespread Dawn-Dusk Sun-Synchronous Orbit (SSO) one.In particular, starting from the mission target, we show that a 49° Mid Inclination Orbit (MIO) in a right-looking StripMap acquisition mode represents a highly effective choice for NIMBUS, as it enhances the systematic coverage of the Italian territory with 6 days of interferometric revisit time and high spatial resolution, thereby facilitating detailed observations of both natural phenomena and anthropic activities.In addition, in terms of Differential Interferometric SAR (DInSAR) performance, we prove that MIO, besides showing no significant limitations for what attains the critical baseline and geometric distortions, allows for the recovery of the North-South deformation component that, conversely, cannot be precisely measured with DInSAR systems operating in SSO.This may lead to future advances in creating 3D deformation maps when considering the synergy between the MIO NIMBUS IRIDE satellites and SSO configurations operating with similar resolutions and wavelengths, as for the COSMO-SkyMed constellation.