Towards Optical Maritime Surveillance with High-Altitude Platforms

Increasing importance and growing needs for monitoring and surveillance of maritime areas are a big challenge, in particular facing current solutions. Conventional aircraft are limited in operation time and range. Moreover, missions are costintensive for extended observations. Remote sensing satellites are suitable for scanning large areas, but they cannot continuously monitor a certain region of interest due to its orbit movement. This gap is going to be closed in the next years by High Altitude Platforms (HAP). HAPs are solar-powered unmanned aerial vehicles, which are capable to continuously operate for weeks or months at altitudes of between 15 and 20 kilometers. This enables long-term quasi-stationary applications while keeping the ability to relocate the platform within a certain range and time. The German Aerospace Center (DLR) researches and develops such a stratospheric platform within an integrated joint project. This aircraft is designed with a wingspan of 27 meters and a maximum take-off weight of about 138 kilograms. It includes a compartment to carry operational payloads with a weight of up to 5 kilograms. This article presents a design of an integrated optical payload system specially tailored to this undergoing development platform. The aim of this novel technology payload is to provide new applications in the field of maritime remote sensing safety and security. The payload fulfills general high-altitude operation requirements. Amongst others this comprises the operation within a wide temperature spread between night / daylight conditions and the on-board real-time image processing at a maximum power consumption of 70 watts in total. Requirements of a HAP-based optical payload system are shown. A design fulfilling these requirements and the communication concept using both, the narrowband and broadband data link, are presented. Furthermore, AI image on-board processing approaches and its application for maritime purposes are discussed.