Bachelor's degree theses

Pre-requirements

In order to apply for any of the following theses or internships, the candidate must have no more than 3 exams left.

Quick-look tools for deep space tracking

At present, the orbit determination of deep space missions relies mainly on Earth-based radiometric measurements, namely ranging, Doppler, and DDOR. These are derived from the properties of the radio link between the spacecraft and one or more ground stations on the Earth. The main sources of noise affecting the radio link are: interplanetary plasma, Earth’s troposphere and ionosphere, thermal noise in the electronics.
The objective of this project is to develop a Python tool to quickly evaluate the quality of the radiometric measurements acquired at the ground stations, without the need of a detailed orbit determination analysis. The candidate will have to retrieve and load all the relevant inputs, including: radiometric measurements, meteorological data, station configuration, spacecraft telemetry. Then, the most important parameters affecting the link quality will be computed and displayed. An automatic test report will be generated.

Ionospheric calibrations for deep space orbit determination

At present, the orbit determination of deep space missions relies mainly on Earth-based radiometric measurements, namely ranging, Doppler, and DDOR. These are derived from the properties of the radio link between the spacecraft and one or more ground stations on the Earth. The main sources of noise affecting the radio link are: interplanetary plasma, Earth’s troposphere and ionosphere, thermal noise in the electronics.
At present, the standard Ionospheric calibrations are computed by analysis of dual-frequency GNSS signals acquired by a global network of high-precision receivers.
The objective of this project is to identify and implement alternative methods to estimate the additional path delay induced by the Earth’s ionosphere. In particular, methods based on parametric models developed for the correction of GNSS measurements will be assessed. The performance of the calibrations will be evaluated by comparison with standard GNSS-based calibrations and by processing of evaluating real mission radiometric data.

Comparative study on Wavelet Transforms in Radiometric Orbit Determination

In the context of modern methods of orbit determination in planetary exploration and radio science experiments, the use of Doppler observables is considered one of the most reliable and accurate. From an engineering point of view, one of the main parameters driving the accuracy of the orbital estimation is the reliability of the algorithms for estimating the carrier frequency of the downlink signal. Currently, the state of the art in the reconstruction of the sky frequency consists in the use of systems called Phase-Locked Loops (PLL) and spectral interpolation methods. The goal of this thesis is to use the wavelet transforms to generate the Doppler observables of spacecrafts active in deep space missions. Wavelet transforms are spectral estimators that provide a variable accuracy in the time and frequency domain, differently from the less manageable fourier transform. The candidate will use the wavelet transform libraries to compare the accuracy of said method to spectral interpolation methods. The nominal frequency will be additionally simulated and generated by the candidate, implementing SPICE kernels from JPL’s NAIF repository.

Uploaded: 15 Feb 2022/AT

Doppler Tracking in Orbit Determination with Telemetry

In the context of modern methods of orbit determination in planetary exploration and radio science experiments, the use of Doppler observables is considered one of the most reliable and accurate. From an engineering point of view, one of the main parameters driving the accuracy of the orbital estimation is the reliability of the algorithms for estimating the carrier frequency of the downlink signal. Currently, the state of the art in the reconstruction of the sky frequency consists in the use of systems called Phase-Locked Loops (PLL) and spectral interpolation methods. The goal of this thesis is to simulate modulated signals (i.e. containing telemetry) and to verify if the currently used frequency estimation methods are suitable in estimating the spacecrafts orbit when there is a Quadrature Amplitude Modulation (QAM). The nominal frequency will be additionally simulated and generated by the candidate, implementing SPICE kernels from JPL’s NAIF repository.

Uploaded: 15 Feb 2022/AT

Comparative study on Generalized Stochastic Resonance in Radiometric Orbit Determination

In the context of modern methods of orbit determination in planetary exploration and radio science experiments, the use of Doppler observables is considered one of the most reliable and accurate. From an engineering point of view, one of the main parameters driving the accuracy of the orbital estimation is the reliability of the algorithms for estimating the carrier frequency of the downlink signal. Currently, the state of the art in the reconstruction of the sky frequency consists in the use of systems called Phase-Locked Loops (PLL) and spectral interpolation methods. The goal of this thesis is to study and implement a generalized stochastic resonance (GSR) method to generate the Doppler observables of spacecrafts active in deep space missions. GSR methods are an innovative solution to solve the non-linear problem of frequency estimation, and their detection threshold is lower than conventional methods, making them ideal to study low signal-to-noise ratio conditions such as atmospheric ingress and egress, bistatic radar, and low SEP angles.

Uploaded: 28 Feb 2022/AT

Interleaving techniques for RF TT&C links during Solar Conjuctions

During Solar Conjunctions, i.e. when the Sun is between the Earth and the S/C, radiofrequency TT&C links can be severely degraded. Having the Sun-Earth-Probe (SEP) angle lower than 3°, introduces deep fading events that can affect several consecutive codeword of the same signal, making communications with the S/C impossible. For this reason, it is important to increase the channel diversity (the number of independent fading levels experienced by each codeword of a transmitted signal). The objective of this project is to use interleaving techniques to increase the channel diversity and see if this can bring any improvement in the signal decoding. The candidate will work with some of the main modulations and coding techniques currently used in Deep Space Missions and test new ones. Everything will be performed using a software developed in MATLAB that is able to simulate a complete link from ground to spacecraft (and back) with the presence of the solar environment.

Uploaded: 2 Mar 2022/AZ

Atmospheric conditions at deep space ground stations through ECMWF re-analysis

Earth-based radiometric tracking data (i.e. Doppler, range, VLBI) are affected by the local atmospheric conditions at the ground station. Typical error sources for the Doppler measurements are represented by: a) fast variations of the water vapor and condensed water content along the antenna line of sight, b) wind-induced vibrations of the antenna structure.
A preliminary error budget for the Doppler measurements can be derived through the knowledge of local atmospheric parameters observed during the tracking session, such as the vertical profiles of the wind speed and direction, and the turbulence strength profile.
The candidate will learn how to extract local atmospheric data from the ERA-Interim and ERA5 databases of the European Center for Medium-range Weather Forecast (ECMWF) with the use of automated MATLAB or Python (preferred) scripts. The extracted datasets will be used to retrieve the vertical profiles of the atmospheric parameters of interest, which will be used to produce a report of the expected tracking performances at the local ground station.

Uploaded: 2 Mar 2022/RLM

Quasars Selection for Delta-DOR Orbit Determination Technique

Very-Long-Base-Interferometry techniques provides angular coordinates information through measures of the differential one-way ranging (DOR). The working principle is based on the observation that, since the wavefront from a distant source arrives to the Earth approximately as a plane wave, the signal at two widely separated antennas will be recorded with a certain time delay. This delay allows to retrieve information about the angular position of spacecraft with respect the ICRF (International Celestial Reference System). The term Delta refers to the use of a quasar signal for calibration purposes since quasar’s position can be settled with exquisite accuracy, about one milliarcsec (1 mas) or better.
The objective of this project is to select suitable quasars for the DDOR observations of Europa Clipper mission to improve the orbit determination of the spacecraft and the moon.
Quasars must be taken from available catalogs and selected by an algorithm to choose only those at a small angular distance from the spacecraft, during each flyby of the mission. The student should work using Python programming language.

Uploaded: 2 Mar 2022/AM

Simulation of rocky body environment geometry for navigation of deep space missions

In order to orbit around a remote celestial body characterized by a solid surface, optical observables which are collected by the onboard cameras are of huge importance. In particular, the images collected during the mission allow for an increased accuracy in the state of the spacecraft with respect to the target deep space object. Measurements obtained by means of radiometric techniques can be combined with optical observables to better fullfill navigation requirements and improving science return, like the estimation of the gravity field and rotational speed of the target of the mission.
This work is about the creation from scratch of the 3D geometry of different solid body types (planets, moons and asteroids) in a parametric way, to provide an input for the simulated optical observables described above. Starting from a clean 3D geometry, and by populating it with craters, riffs, boulders which can be parametrically and arbitrary modified, the student will then match the features to the real crater distribution found in literature. The results will be obtained by a photometric model, which will allow a direct coparison with images of real missions to similar space objects.

Uploaded: 2 Mar 2022/FF