A Solution to the Flyby Anomaly Riddle

The Flyby Anomaly is one of the unsolved problems of current physics in that the Doppler-shift determined speeds are inconsistent with expected values assuming the validity of Newtonian gravity. We postulate that the Flyby Anomaly is a consequence of the assumption that the speed of light is isotropic in all frames, and invariant in the method used to measure the velocity of the space probes by means of the Doppler Effect. The inconsistent anomalous values measured: positive, null or negative are simply explained relaxing this assumption. During space probe energy assistance maneuvers the velocity components of the probe in the direction of the observer [V.sub.o] are derived from the relative displacement A f of the radiofrequency f transmitted by the probe, multiplied by the local speed of the light c' by the Doppler effect: [V.sub.o] = ([DELTA]f /f) c'. According to the Ceispedes-Curei hypothesis, the movement through variable gravitational energy density fields produces slight variations of the refractive index n' of space and therefore of the speed of light c' which leads to unaccounted corrections of the Doppler data that are based on an invariant c. This leads to incorrect estimates of the speed or energy change in the flyby maneuver in the Earth's frame of reference. The simple theory presented is applied to hyperbolic flyby trajectories of Galileo I and the spacecraft NEAR accurately reproducing the NASA measured values and thereby providing additional experimental evidence for a variable speed of light dependence on the gravitational energy density of space with fundamental consequences in astrophysics and cosmology.