As the European Space Agency makes final preparations for the 10 October launch of the second pair of Europe's Galileo navigation satellites to start a fast-track launch programme to orbit a functional constellation of 18 satellites by 2014, the agency is already lining up a second-generation constellation - for launch from 2020 - to ensure continuous service.
Although the first Galileo constellation has yet to provide useful navigational signals - two satellites were launched a year ago and once the second pair are in orbit it will be possible to validate system performance during the winter - it will take 18 spacecraft to provide a useful service and 26, by end-2015, for near global coverage. The full constellation of 26 spacecraft and six orbiting spares should be deployed by 2019.
However in a programme update yesterday at ILA, ESA's Galileo programme director Didier Faivre said the spacecraft have a 10-year design life so it must start replacing the first units from 2020.
Thus, he said, one key budget request to the agency's conference of member-state ministers in November will be for authorisation to begin spelling out the specifications for spacecraft in 2013 that can be contracted for construction from 2017.