The effect of general relativity on hyperbolic orbits and its application to the flyby anomaly

Abstract

We investigate qualitatively and quantitatively the impact of the general relativistic gravito-electromagnetic forces on hyperbolic orbits around a massive spinning body. The gravito-magnetic field, which is the cause of the well known Lense-Thirring precessions of elliptic orbits, is generated by the spin S of the central body. It deflects and displaces the trajectories differently according to the mutual orientation of S and the orbital angular momentum L of the test particle. The gravito-electric force, which induces the Einstein precession of the perihelion of the orbit of Mercury, always deflects the trajectories inward irrespective of the L-S orientation. We numerically compute their effect on the range r, radial and transverse components v_r and v_\tau of the velocity and speed v of the NEAR spacecraft at its closest approach with the Earth in January 1998 when it experienced an anomalous increase of its asymptotic outgoing velocity v_\infty o of 13.46 +/- 0.01 mm sec^-1; while the gravito-electric force was modeled in the software used to process the NEAR data, this was not done for the gravito-magnetic one. The range-rate and the speed are affected by general relativistic gravito-electromagnetism at 10^-2 (gravito-electric)-10^-5 (gravito-magnetic) mm sec^-1 level. The changes in the range are of the order of 10^-2 (gravito-magnetic)-10^1 (gravito-electric) mm.