Urgent message apparatus and system

An urgent message system in which an urgent message apparatus mounted in a vehicle transmits, in an emergency, an urgent message with the use of a backup battery by means of a low-earth orbit satellite, comprising a center which manages said low-earth orbit satellite and carries out communication with said urgent message apparatus with the use of said low-earth orbit satellite, wherein:

• said urgent message apparatus detects a current position of the vehicle;
• and
• transmits the detected vehicle current position to the center;
• and
• when receiving the vehicle current position from said urgent message apparatus, said center transmits time period in which communication with said low-earth orbit satellite is unavailable for said position, to said urgent message apparatus;
• said urgent message apparatus then receives the time period in which communication with the low-earth orbit satellite is unavailable from the center;
• calculates a power amount required when said backup battery is kept in a transmission standby state during said time period in which communication with the low-earth orbit satellite is unavailable;
• measures remaining power of said backup battery;
• and
• compares a sum of a power amount required for transmitting the urgent message and the power amount thus calculated, with the remaining power thus measured, and determining that charging or replacement of said backup battery is required when said sum is larger than the remaining power.