6.1.1 Global Coverage
Each of the satellite systems that is used by Cospas-Sarsat provides global coverage in a different manner.
The spacecraft of the LEOSAR system carry SAR Processor (SARP) instruments; these instruments collect the data received from distress beacons as they pass over each beacon. This data is stored in a memory on the spacecraft and is played back continuously for as long as it remains in the satellite memory. Based on current beacon population and activity levels, the existing LEOSAR satellites have enough memory to retain data for approximately 18 hours. This is sufficient to ensure that the satellite will be able to transmit the data from every beacon that it passes over to an active LEOLUT well before the data has been cycled out of the spacecraft memory.
The MEOSAR system has not (in 2020) achieved Full Operational Capability (FOC). The network of MEOLUTs that was in operation during the MEOSAR Demonstration and Evaluation Phase demonstrated a capacity for almost complete global coverage, with only a few identified gaps. New MEOLUTs are planned that will provide coverage over these gaps; they will be operational before the declaration of MEOSAR FOC.
The GEOSAR system provides complete coverage for the detection of 406 MHz distress beacons over all parts of the Earth between 75˚ South latitude and 75˚ North latitude. The gaps around the poles are inherent to the nature of the geostationary orbits and cannot be eliminated. These gaps are addressed by the other (LEOSAR or MEOSAR) space systems.
It is expected that the LEOSAR system will eventually be phased out, and the future Cospas-Sarsat System will be a GEOSAR / MEOSAR system.