Interferometric observations of an artificial satellite.

Area of Science:

• Radio astronomy
• Geodesy
• Satellite dynamics

Background:

• Accurate satellite orbit determination is crucial for navigation, communication, and scientific missions.
• Traditional tracking methods have limitations in precision and global coverage.

Purpose of the Study:

• To assess the feasibility of using Very-Long-Baseline Interferometry (VLBI) for precise satellite tracking.
• To determine the orbital parameters of the TACSAT synchronous satellite using VLBI.

Main Methods:

• VLBI observations of radio signals from the TACSAT satellite were conducted over 7 hours.
• Differenced delay and delay-rate measurements were analyzed to deduce the satellite's orbit.

Main Results:

• An excellent orbit for the TACSAT satellite was determined.
• Achieved precision in differenced delay measurements of 0.15 nanoseconds (approx. 5 cm).
• Achieved precision in delay-rate measurements of 0.05 picoseconds/second (approx. 0.002 cm/s).

Conclusions:

• The initial three-station experiment demonstrates VLBI's capability for accurate satellite tracking.
• VLBI shows significant potential for high-precision geodesy applications.
• VLBI offers a viable alternative or complementary technique to existing satellite tracking methods.