LATOR: Its science product and orbital considerations

摘要

In a LATOR mission to measure the non-Euclidean relationship between three sides and one angle of a light triangle near the Sun, the primary science parameter, to be measured to part-in-10(9) precision, is shown to include not only the key parametrized post-Newtonian (PPN) gamma, but also the Sun's additional mass parameter, MG, which appears in the spatial metric field potential. MG may deviate from the Sun's well-measured gravitational mass due to post-Newtonian features of gravitational theory not previously measured in relativistic gravity observations. Under plausible assumptions, M-Gamma is a linear combination of the Sun's gravitational and inertial masses. If LATOR's two spacecraft lines of sight are kept close to equal and opposite relative to the Sun during the mission's key measurements of the light triangle, it is found that the navigational requirements for the spacecraft positions are greatly relaxed, eliminating the need for on-board drag-free systems. Spacecraft orbits from the Earth to achieve the equal and opposite passages by the Sun's, line of sight are illustrated.