Spacecraft tracking

Radio Science Research

Introduction

VLBI radio telescopes are used for tracking space craft in the Solar System for planetary exploration. The craft are equipped with high-power transmitters to enable communication with Earth throught the Deep Space Network facilities. These usually operate in two-way mode, where the signal transmitted is locked to the reference clock down at the station. VLBI antennas operate in three-way mode where the the receiving antenna is separated by a far distance from the transmitter.

VLBI radio telescopes are located all around the globe to provide large spatial coverage to obsereve the farthests and weakest radio astronomical sources. The amount of radio telescopes and the disperse location makes the use of these antennas for deep space a benefit to enhance the next generation of space missions. Most of these antennas include a receiver that covers the standard deep space communication bands (2.2 and 8.4 GHz). Development is made to cover the 32 GHz band in the near future. These radio telescopes along the communications systens on board the spacecraft constitutes the major elements of the radio science instrumentation.

The Univeristy of Tasmania operates 6 radio telescopes that are used for radio science exploration on a regular basis.

Radio science investigates th small changes in the phase, frequency and amplitude of the radio signal propating from a craft to the Earth. These small variations are used to study atmopheric and ionospheric structure of planets and satellites,planetary gravitational fields, shapees, masses, planetary rings, ephemerides of planets, solar plasma, coronal mass ejections, magnetic fields, cometary comae and aspects of general relativity as gravitational redshift.