On the Geodetic Feasibility of Mars with VLBI Observables from Mars Probe
Based on the observation of Mars probe with ground VLBI, the observation model including the position of Mars probe and connection parameters of reference systems is studied in this paper, and the estimable parameter sequence is determined. Then the adjustment method appropriate for rank defect in the matrix of normal equation coefficients is studied, the model parameters are calculated and their precisions are evaluated. Thirdly, the impact of accidental errors to the parameters is analyzed. The results are given at the end of the paper.
Relativistic VLBI Delay Model for Finite Distance Radio Source
When very long baseline interferometry (VLBI) is applied to observation of finite distance radio source from observer and the curvature of the the wave front cannot be approximated as plane wave. Thus current standard VLBI model (‘Consensus model’) does not have enough accuracy and an alternative precise VLBI delay model for finite distance radio source corresponding to the ‘Consensus model’ is required in observation of radio source in the solar system (e.g. planets, asteroids, and spacecraft). We derived a formular of relativistic VLBI delay model for finite distance radio source by taking into account coordinates transformation by using linearized PPN metric. This model is valid in order of several pico seconds accuracy when the radio source is at distance beyond 109 m. Our model include the ‘Consensus model’ as a special case that radio source is at infinite distance form the observer.
A picosecond accuracy relativistic VLBI model via Fermi normal coordinates
We use Fermi normal coordinates to construct transformations relating solar system barycentric coordinates to local inertial geocentric coordinates. We then calculate relativistic corrections to terrestrial VLBI measurements. We develop our formalism to include corrections needed for picosecond accuracy. We also include a calculation of photon time delay which includes effects arising from the motion of gravitational sources.