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Gravity Probe B is a satellite and associated experiment to test some of general relativity's (GR's) predictions: frame dragging and the geodetic effect, an effect of curvature of spacetime. The satellite was launched in 2004 and was active until 2010. The satellite carries gyroscopes with advanced technology to reduce extraneous influence on their directions plus the measuring equipment to track their directions with minimal disturbance. The experiment also required the data collection necessary to precisely to track the gyroscopes' directions relative the celestial sphere. Both GR effects were confirmed during the experiment, the frame dragging more clearly than the geodetic effect.