Europe's alternative to the USA's global positioning system (GPS) may only have four satellites in orbit, but European Space Agency (ESA) officials are confident that constellation delivers a valid service.
ESA boffins revealed this week that since March 2013 test vehicles around the world have run tests to determine the accuracy of positions returned by Galileo satellites in what was called the “ In-Orbit Validation (IOV) phase” of testing. More than 10,000 kilometres of driving later, “Many terabytes of IOV data were gathered,” according to Marco Falcone, ESA’s Galileo system manager, and once they had been analysed the data showed that “Galileo’s observed dual-frequency positioning accuracy is an average 8 m horizontal and 9 m vertical, 95% of the time. Its average timing accuracy is 10 billionths of a second”.
The tests also showed that 77 per cent of simulated distress locations could be located to within two kilometres and 95 per cent to within five kilometres. Alerts reached Galileo's mission control in 90 seconds, nicely below the design requirement of ten minutes.
All of which is apparently more than good enough for the applications Galileo's backers have in mind.
That's good news because six new Galileo satellites are due to go aloft in 2014, and will now do so safe in the knowledge that the project's design is valid. Galileo's plan calls for a constellation of 30 satellites by the end of the decade. ®