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News  Europe’s navigation pioneer GIOVE-A celebrates sixth birthday in space
GIOVE-A, ESA’s prototype navigation satellite, remains operational after six years in space. Its flight paved the way for Europe’s Galileo satellites, the first two of which joined GIOVE-A in medium-Earth orbit on 21 October this year. The first ‘Galileo In-Orbit Validation Element’, GIOVE-A, was launched on 28 December 2005 by a Soyuz rocket from Baikonur in Kazakhstan, carrying a prototype rubidium atomic clock destined for the Galileo constellation. GIOVE-A had a multiple role in advancing the Galileo programme: besides flight-testing hardware it also secured the radio frequencies provisionally allocated to Galileo by the International Telecommunications Union and performed testing of the medium-Earth orbit radiation environment.
It was joined by GIOVE-B on 27 April 2008, which was equipped with an ultra-precise passive hydrogen maser atomic clock as well as a second rubidium atomic clock. Galileo satellites carry both clock designs for maximum reliability.
This longevity is partly the result of a relatively tranquil solar cycle leading to decreased radiation exposure, as well as design margins built into the satellites. GIOVE-A was constructed by Surrey Satellite Technology Ltd of the UK while GIOVE-B was the work of a consortium led by Astrium.
The GIOVE satellites are still doing useful work: they are testbeds for experimentation, and give information on how the functioning of Galileo payloads may evolve over the course of their planned 12-year working lifetimes.
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