On the suitability of a TerraSAR-L Interferometric Cartwheel for ocean current measurements

The main idea behind the French "Interferometric Cartwheel" and similar other concepts is to put some small satellites with synthetic aperture radar (SAR) receivers into slightly different orbits behind a bigger master satellite in such a nay that sufficient baselines for cross-track interferometry between at least two satellites are always available. In a recent study for ESA, the potential of such configurations in combination with the upcoming ESA satellite TerraSAR-L was investigated. Favorable cross-track baselines for land applications would be on the order of several kilometers. We discuss the suitability of such configurations for ocean current measurements by along-track interferometry. The main parameter to be considered is the time lag between pairs of satellites, which may be changing continuously. We find that reasonable current measurements can be expected for a long-track satellite spacings of about 10 to 1000 m. This wide range of suitable baselines should permit the design of a satellite configuration with continuously good performance for topographic measurements and current measurements.