Galileo, as well as providing global navigation, relays SOS messages to first responders. And, now the satellites will also reply to those SOS messages, assuring senders that help is on its way.
The ESA-designed ‘return link’ system - unique to Galileo - was declared operational last week, during the 12th European Space Conference.
Delivery time for the return link acknowledgement from initial emergency beacon activation is expected to be 2 minutes in the majority of cases, and up to 30 minutes maximum - depending primarily on time it takes to detect and locate the alert.
ESA’s Galileo principal SAR engineer explains: ‘Anyone in trouble will now receive solid confirmation, through an indication on their activated beacon, informing them that SAR services have been informed of their alert and location. For anyone in a tough situation, such knowledge could make a big difference.’
Galileo’s medium-orbiting satellites - at 23,222 km altitude – contribute to the Cospas-Sarsat system, providing a wide ground view by multiple satellites, combined with time-of-arrival and doppler ranging techniques, to localise SOS signals. This improves the historic maximum signal detection time from 4 hours to less than 5 minutes - with accuracy down to 1-2 km (well within the formal specification of 5 km within 10 minutes).