The Gravity Probe B (GP-B) satellite was launched by NASA in 2004 to test, among other things, the effect predicted by general relativity that the Earth would drag inertial frames with it as it rotates. T W Murphy Jr of the University of California and colleagues have argued that as the frame-dragging effect is a consequence of gravitomagnetism it has already been confirmed by lunar laser ranging measurements in the Earth–Moon system to a higher accuracy than GP-B will provide. That said, the data from the sophisticated gyroscope system on GP-B are still interesting since they will provide a very direct measurement. GP-B will also test a related general relativistic effect, the "geodetic effect", which is an additional gravitation-induced precession.