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Projecte llegit

Títol: Very-long-baseline Interferometry for radio-tracking deep space vehicles

Estudiants que han llegit aquest projecte:

Director/a: ÚBEDA FARRE, EDUARD

Departament: TSC

Títol: Very-long-baseline Interferometry for radio-tracking deep space vehicles

Data inici oferta: 14-07-2022     Data finalització oferta: 14-03-2023


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Very-long-baseline interferometry; Differential one-way ranging; Deep space network; Voyager Interstellar Mission
 
Descripció del contingut i pla d'activitats:
The deep space path of probes under Interstellar mission, such as Voyager (among others), is tracked through the so-called Deep Space Network (DSN) ground facilities, located in the United Stated (Goldstone, California), Spain (Madrid) and Australia (Canberra). Each complex consists of at least for terminals equipped with ultra-sensitive receiving systems and large parabolic-dish (Cassegrain) antennas, with 34-meter or 70-meter diameters.

Differential one-way ranging (DOR) is a radio-technique that has turned out very useful in the orbit determination of some deep-space vehicles, such as spatial probes. It requires two DSN stations and applies Very-long-baseline interferometry (VLBI), which shares fundamentally the same principles involved in interferometers with connected elements. However, it requires important buffering resources to manage huge amounts of data that need to be cross-correlated. Although decades ago this could only be done by remote magnetic or disk storage, nowadays data can be transmitted over the internet in quasi real time.

In this project, a thorough study of the Delta-DOR technique for radio-tracking the Voyager 1 or 2 probes is requested. The Delta-DOR technique calibrates the orbit-angular VLBI-location through the a priori knowledge of a well-established celestial location (typically a quasar). Realistic results on the interferometric scheme of reception by downlink converting to Intermediate frequency and cross-correlating the received signals by two stations will be carried out. Attention will be driven to the efficient estimate of the relative delay or phase between the two stations by monitoring a few frequency channels with moderate bandwidth. The effects on the improved angular ambiguity will be assessed. Other effects, such as dispersive scintillation and thermal or cosmic noise may also be considered.
 
Overview (resum en anglès):

The objective of this project is to present a comprehensive understanding of the communication systems used in space navigation, with a particular focus on the tracking techniques employed by the Deep Space Network (DSN). The study covers a wide range of fundamental and complex concepts to provide a holistic understanding of this field. In addition to radio communication techniques and the corresponding receivers, other areas of interest such as Optical Communications, radio science, and Very Long Baseline Interferometry (VLBI) applications have been explored. By doing so, the project contributes to expanding the overall understanding and the diversity of approaches in this research field.

The project encompasses both theoretical and practical aspects. The theoretical chapter delves into operational principles of the main tracking techniques currently in use, while the practical section aims to apply the acquired knowledge and further deepen the understanding. This last chapter takes as a reference the Voyager Interstellar Mission (VIM) to define the initial conditions within a plausible context. It is divided into two sections. The first section involves the simulation of a telemetry signal and the analysis of its behavior based on the modulation index. In the second section, the delta-DOR technique is simulated, which is extensively used by the DSN when other tracking techniques prove to be imprecise. The objective is to validate and analyze the performance of this technique. The project outcomes have successfully met the expected results, providing a solid foundation for future investigations in the field of space navigation tracking systems.

A rigorous and systematic methodology has been employed to conduct the research. A scientific approach has been followed, involving the collection and analysis of relevant data, formulation of hypotheses based on logical reasoning, conducting simulations, and interpreting results. Special attention has been given to ensuring the validity and reliability of the obtained results.

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