Wake-based detection of dark ships in SAR images for improving security of seas

The ARGO project brings forward an innovative concept in the field of Maritime Situational Awareness (MSA). Currently, the maritime traffic monitoring is mainly supported by the Automatic Identification System (AIS), a system in which medium and large ships (>300 tons) are equipped by a transponder transmitting vessels identification data and information about their route, enabling ship-to-ship and ship-to-shore data exchange within about 60 nautical miles from the coast. The AIS system is conceived on a collaborative approach: only the ships whose AIS transponder is turned on can be detected and monitored. Hence, non-collaborative vessels do not leave a trace in the AIS system. The ARGO project aims to improve the security of ships providing an effective understanding of maritime traffic, including also non-collaborative vessels. Currently, several space-based monitoring systems have been proposed and tested. All of them carry out the ship detection based on echoes in optical or radar images. This have strongly improved the MSA in the last decade, but such systems are useless to fight against illegal activities performed by go-fast boats. In fact, this kind of vessels, thanks to their design, materials and high speed, cannot be imaged in radar images and the illegal activities are typically performed during the night-time when optical sensors cannot provide data. However, thanks to their high velocity and narrow beam, these boats are likely to produce long visible wakes. Such wakes are very persistent, lasting for distances of several kilometers, and they can be observed in Synthetic Aperture Radar (SAR) imagery. Hence, ARGO project will enable the space-based surveillance of seas under all weather and day-and-night conditions, overcoming the idea of the ship detection based on echoes in optical or radar images and exploiting the wake presence as an indirect signature of the ship presence. The unique capabilities of the proposed system make it suited for the detection of very fast ships, typically used for illegal affairs, strongly contributing to border security and passengersgoods safety.