GSAT0002 or GIOVE-B is the second of the test versions of the 30 craft European Union navigational fleet that is planned to be launched beginning 2010. It was launched by a Soyuz-Fregat rocket from Baikonur at 22:16 UT on 26 April 2008. (A similar version, GIOVE-A, was launched in December 2005.) The 500 kg craft carries two (redundant) Rubidium atomic clocks, and an even more precise Passive Hydrogen Maser with an accuracy of one nanosecond/day. It also carries a radiation-monitoring payload, and a laser retro-reflector for high-accuracy laser ranging. When completed, this Galileo fleet will become the third available fleet, after the long-functional GPS and the to-be-completed GLONASS fleets.