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

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.

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.

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*

Code: LT22WAVEOD

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*

Code: LT22DTLMOD

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*

Code: LT22GSRROD

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*

Code: LT22RFTTSC

Earth-based tracking data (i.e. Doppler, range, VLBI) are affected by the local atmospheric conditions at the ground station. Typical error sources for these measurements are represented by: a) fast variations of the water vapor content along the antenna line of sight, b) wind-induced vibrations of the antenna mechanical structure. A preliminary error budget for the Doppler measurements can be obtained from the knowledge of local atmospheric conditions during each tracking session (i.e. wind speed and direction, turbulence strength). The candidate will learn how to extract local atmospheric data from the ERA-Interim database of the European Center for Medium-range Weather Forecast (ECMWF), developing dedicated Python (or C++) codes. Vertical profiles for the extracted atmospheric parameters will be used to produce a Doppler error budget for selected BepiColombo tracking passes and compared to measured Doppler performance.

*Uploaded: 2 Mar 2022/RLM*

Code: LT22ESATRO

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*

Code: LT22SIMOPN

Onboard navigation and attitude estimation systems are very important elements of a space exploration mission, and they should be designed to be safe and reliable. In this context, a Kalman Filter is a very powerful tool, since it permits to optimally estimate the variables of interests when they can't be measured directly, but an indirect measurement is available. The objective of this thesis work is to test an already available Extended Kalman Filter (EKF) in different ways to optimize it's performances and in parallel to develop a neural network algorithm to perform an auto-tuning of it's parameters. Eventually the student can also try to use Neural Networks to improve the filter estimation.

*Uploaded: 23 Feb 2023/AZ*

Code: LT23NNKALF

Astrometric observables (i.e. right ascension and declination coordinates in the plane of the sky) are typically used to estimate the heliocentric trajectory of near-Earth asteroids and comets. The purpose of this thesis is to perform a literature review of the main error sources affecting these measurements and to develop mathematical tools for estimating their magnitude in realistic scenarios.

The candidate will then test these tools by retrieving astrometric observables of comet 67P/Churyumov-Gerasimenko (target of the Rosetta mission) and of the binary asteroid Didymos (target of the Hera mission) from the Minor Planet Center (MPC) database and performing a “pass-through” using know target ephemerides.

*Uploaded: 24 Feb 2023/RLM*

Code: LT23ESASTR

Light-curves observables (i.e. time-varying magnitude of radiation flux received by an observer) are typically used to determine periods of rotation and/or revolution of target celestial bodies, provided a rough knowledge of their shape and size is available. This thesis aims to perform a detailed literature review of the mathematical models required to compute the light-curves for a target body and to implement these tools via Python (or C++) codes. The candidate will then apply these tools for the estimation of some key physical parameters of the binary asteroid system Didymos (target of the Hera mission), comparing the obtained results with those in the literature.

*Uploaded: 24 Feb 2023/RLMCode: LT23HERALC*

Navigation of spacecraft is mostly based on radiometric data. These consist of the information content of electromagnetic signals transmitted from the spacecraft to a tracking station. Currently, multiple networks of deep space stations exist, all of which support different space exploration missions. In this context, the receivers on the ground can be different in architecture, and provide radiometric data in different formats. These datasets can contain hours of tracking data, making them difficult to manage and transmit to radio science and navigation users. The current solution to this problem is for the tracking stations to output binary files, which are not directly readable by users. The aim of this thesis is to identify and characterize the most common dataset formats, with a focus on NASA and ESA receivers, and to create conversion scripts to make them readable and exportable to different computing languages (Python/MATLAB)

*Uploaded: 25 Feb 2023/ATCode: LT23DATARW*

Bistatic radar radio science experiments have been employed for years to remotely probe planetary surfaces. When a radio signal is sent to a target planet and reflected from its surface, roughness at scales proportional to radar wavelengths, as well as electrical properties of surface materials, can be inferred from planet’s echoes.

Developed by ESA to explore the Jovian system, the JUICE spacecraft will perform radio science experiments on the three icy moons of Jupiter: Ganymede, Callisto and Europa. This thesis work is about investigating opportunities for the JUICE orbiter to perform bistatic radar observations of Callisto during the Jupiter Tour of the mission. The candidate will model the geometry of a bistatic radio link from JUICE to Earth bouncing off Callisto, and carry out a preliminary assessment of bistatic radar observations of the icy moon of Callisto. Parameters of interest in the feasibility analysis will be the angle of incidence and the expected signal-to-noise ratio of the echoes.

Working time: ≈2 months

Software: Matlab/Python

*Uploaded: 29 Jun 2023/GB*

Code: LT23JUBRCL

The JUICE Mission, developed by ESA to explore the Jovian system, will orbit the gas giant and its icy moons Ganymede, Callisto and Europa from 2031 to 2035. During the final orbital phase around Ganymede, main target of the mission, the spacecraft will have numerous opportunities to probe its surface by means of bistatic radar (BSR) experiments.

The icy moon of Ganymede features two remarkably different geologic terrain types, i.e., the bright and dark terrains. Water-ice is responsible for the brightness of two-thirds of the total planet. The darker texture of the remaining regions is due to the presence of a thin, dark layer of poorly constrained tholins overlying the icy subsurface. Dual-band BSR observations by JUICE can provide a substantial contribution to the compositional characterization of these dark terrains.

The purpose of this thesis work is to address opportunities for JUICE to probe the dark terrains of Ganymede by means of BSR during the Ganymede Orbital Phase. The candidate will model the bistatic radio-link between JUICE and Earth bouncing off Ganymede, and isolate the time windows of observation where JUICE illuminates dark regions in favorable geometric conditions for BSR experiments to be carried out.

Working time: ≈2 months

Software: Python

*Uploaded: 29 Jun 2023/GB*

Code: LT23JUBRGT