Galileo In-Orbit Validation Experiment

The second ‘Galileo In-Orbit Validation Experiment’ mission, launched on 27 April 2008, GIOVE-B carries both types of atomic clocks being used by the Galileo system: a rubidium clock, accurate to three seconds in one million years, and a passive hydrogen maser – the first clock of its kind flown in space – accurate to one second in three million years.

It is also fitted with an antenna to illuminate Earth with its test signal, linked to a signal generation unit able to produce the kind of complex modulated signals required for the interoperation of Galileo with the US GPS system. 

GIOVE-B also carries ESA’s advanced Standard Radiation Monitor to survey the radiation environment in this orbit.

After more than four years of service, GIOVE-B’s payload was turned off on Monday 23 July 2012, in preparation for the following day’s thruster firing.