On detecting the gravitomagnetic field of the earth by means of orbiting   clocks
  Based on the recent finding that the difference in proper time of two clocks in prograde and retrograde equatorial orbits about the Earth is of the order 10^{-7}s per revolution, the possibility of detecting the terrestrial gravitomagnetic field by means of clocks carried by satellites is discussed. A mission taking advantage of this influence of the rotating Earth on the proper time is outlined and the conceptual difficulties are briefly examined. 
H.I.M. Lichtenegger, F. Gronwald, and B. Mashhoon