The Automatic Identification System (AIS) is mandated by the International Maritime Organization for all vessels displacing over 300 tons. AIS transponders automatically broadcast information at regular intervals.
These signals are received by AIS transponders installed on other ships or by land-based systems. The signals have a horizontal range of about 40 nautical miles (74 km), meaning that AIS traffic information is only available around coastal zones or in a ship-to-ship zone.
Satellite-Based Automatic Identification Systems (SAT-AIS) improve vessel tracking and location. Due to the nature of their activity, it is common for transatlantic vessels, ships or fishing vessels, to mention just a few examples, to spend long periods of time at sea, in isolated areas where it is not possible to rely on land-based networks to guarantee precise control over their location at all times.
The use of small satellite constellations can improve the safety of all types of vessels and can be an effective measure to prevent certain common problems related to maritime traffic, such as piracy and illegal fishing.