Abstract: Two sensors are carried on board a spacecraft: a first, low resolution "preview" sensor, and a second high resolution "fine sensor", the latter having sensing parameters which can be adjusted to satisfy the needs of a particular customer. The instantaneous field of view of the preview sensor is located at a fixed distance ahead of that of the fine sensor, so that within a predetermined time period, users may decide which partial data are to be transmitted by the fine sensor and under which observation parameters (such as spacial resolution, spectral channels, measuring site, size of the measured area) to their earth station in near real time, still within the course of the actual overflight. Compilation of the specific data requested by the customers takes place on-board the spacecraft upon telecommands by the customers themselves. Sensing of the data requested by the customer is then performed by the fine sensor.

Abstract: The invention provides a system and a method for detection of oil spills and icebergs at sea and for aiding the navigation of ship traffic to avoid collisions between ships and icebergs. A constellation of polar orbiting satellites is used to determine the position of icebergs and oil spills within an observation area, and this information is transmitted to a data processing center which also receives information concerning the position of ships within the observation area. The data processing center uses this information to evaluate the likelihood of collisions between ship and icebergs and sends warning signals to the ships, alerting them to the danger. The data processing center also correlates the position of ships and oil spills to determine the likely cause of the latter.