Role of the Orbital Tube in Interferometric Spaceborne SAR Missions

The orbit for Earth observation satellite SAR missions is maintained within an Earth-fixed orbital tube to ensure ground-track coverage repeatability, and consequently, enable repeat-pass interferometric compatibility between data takes. In this letter it is shown that the size of the orbital tube may impact the interferometric performance in terms of azimuth spectral decorrelation and azimuth coregistration accuracy under the presence of squint. These effects require special consideration for SAR burst modes, such as ScanSAR or TOPS (i.e., Terrain Observation by Progressive Scans). The paper presents and analyses these aspects in the frame of the Sentinel-1 mission