"Imprinting" in General Relativity Tests?

Abstract

We investigate possible a-priori "imprinting" of general relativity itself on spaceraft-based tests of it. We deal with some performed or proposed time-delay ranging experiments in the Sun's gravitational field. The "imprint" of general relativity on the Astronomical Unit and the solar gravitational constant GM_\odot, not solved for in the so far performed spacecraft-based time-delay tests, may induce an a-priori bias of the order of 10^-6 in typical solar system ranging experiments aimed to measuring the space curvature PPN parameter \gamma. It is too small by one order of magnitude to be of concern for the performed Cassini experiment, but it would affect future planned or proposed tests aiming to reach a 10^-7-10^-9 accuracy in determining \gamma.