First Galileo navigation message transmitted
GIOVE-A, the first Galileo satellite, has successfully transmitted its first full navigation message containing the information needed for users to calculate their position. The message sent is similar to those that will be sent by the Galileo system when it becomes fully operational, and the successful transmission of this first message marks an important milestone in the validation of the system design, according to the European Space Agency (ESA). The transmission has two components: a navigation signal and a navigation message. The navigation signal provides information which allows the user to measure the distance from the satellite to the receiver. The navigation message contains the information needed to calculate the time and exact position of the satellite. The navigation message is generated by the GIOVE Processing Centre in the Netherlands. A worldwide network of sensor stations tracks the signal-in-space from GIOVE-A. These send the information to the GIOVE Processing Centre, which uses the data to compute the satellite's flight path and on-board clock model. It then comes up with a prediction of the orbital path and clock performance for the near future, which is the basis of the navigation message. Together, the sensor stations and the Processing Centre form the GIOVE Mission Segment, and the goal of the test message was to demonstrate an end-to-end link between the Mission Segment and the user receivers. In this first test run, the navigation message was uplinked to GIOVE-A from a ground station in Surrey, the UK. Soon, GIOVE-A will begin to continuously broadcast the navigation message, which will be updated whenever the satellite is visible from the Surrey uplink station. The Galileo system, which is run jointly by the ESA and the European Commission, is due to become fully operational in the next decade.