The much smaller frame-dragging effect is an example of gravitomagnetism. It is an analog of magnetism in classical electrodynamics, but caused by rotating masses rather than rotating electric charges. Previously, only two analyses of the laser-ranging data obtained by the two LAGEOS satellites, published in <time>1997</time> and <time>2004</time>, claimed to have found the frame-dragging effect with an accuracy of about 20% and 10% respectively, whereas Gravity Probe B aimed to measure the frame dragging effect to a precision of 1%. However, Lorenzo Iorio claimed that the level of total uncertainty of the tests conducted with the two LAGEOS satellites has likely been greatly underestimated. A recent analysis of Mars Global Surveyor data has claimed to have confirmed the frame dragging effect to a precision of 0.5%, although the accuracy of this claim is disputed. Also the Lense–Thirring effect of the Sun has been recently investigated in view of a possible detection with the inner planets in the near future.