Spacecraft VLBI and Doppler tracking: algorithms and implementation

D. A. Duev^1,2, G. Molera Calvés^1,3, S. V. Pogrebenko¹, L. I. Gurvits^1,4, G. Cimó¹ and T. Bocanegra Bahamon^1,4,5

¹ Joint Institute for VLBI in Europe, PO Box 2, 7990 AA Dwingeloo, The Netherlands
e-mail: duev@jive.nl; molera@jive.nl; pogrebenko@jive.nl; lgurvits@jive.nl; cimo@jive.nl; bocanegra@jive.nl
² Faculty of Physics, Lomonosov Moscow State University, GSP-1, Leninskie gory, 119991 Moscow, Russia
³ Aalto University Metsähovi radio observatory, Metsähovintie 114, 02540 Kylmälä, Finland
⁴ Department of Astrodynamics and Space Missions, Delft University of Technology, 2629 HS Delft, The Netherlands
⁵ Shanghai Astronomical Observatory, 80 Nandan Road, 200030 Shanghai, PR China

Received: 25 January 2012
Accepted: 9 March 2012

Abstract

Aims. We present the results of several multi-station Very Long Baseline Interferometry (VLBI) experiments conducted with the ESA spacecraft Venus Express as a target. To determine the true capabilities of VLBI tracking for future planetary missions in the solar system, it is necessary to demonstrate the accuracy of the method for existing operational spacecraft.

Methods. We describe the software pipeline for the processing of phase referencing near-field VLBI observations and present results of the ESA Venus Express spacecraft observing campaign conducted in 2010−2011.

Results. We show that a highly accurate determination of spacecraft state-vectors is achievable with our method. The consistency of the positions indicates that an internal rms accuracy of 0.1 mas has been achieved. However, systematic effects produce offsets up to 1 mas, but can be reduced by better modelling of the troposphere and ionosphere and closer target-calibrator configurations.