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.
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
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
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/AT
Code: LT23DATARW
The Potentially Hazardous Asteroid (PHA) 99942 Apophis will make an extremely close approach (~37000 km) to Earth on 13 April 2029, so close that tidal stresses and torques may cause resurfacing or reshaping of the body and changes in its spin state.
This thesis aims to estimate the heliocentric orbit of Apophis using astrometric and radar data publicly available on the Minor Planet Center and other affiliated repositories.
The candidate will perform a literature review of the current dynamical model for Apophis, retrieve and process previous astrometric and radar measurements, and perform an ephemeris reconstruction using the ESA/ESOC flight dynamics software GODOT. This solution will then be compared with the currently available trajectories from the literature.
Uploaded: 22 Nov 2023/RLM
Code: LT23APOEPH
Between 2006 and 2016 the Cassini spacecraft carried out 13 bistatic radar (BSR) observations of the surface of Saturn’s largest moon, Titan. Employing the spacecraft’s 4-meter antenna for transmission of an unmodulated signal to the moon’s surface, and collecting reflections from it at Deep Space Network stations, it is possible to gather an unvaluable dataset of echoes from Titan’s diverse terrains.
Thanks to a synergy of instruments on-board the Cassini spacecraft, Titan was revealed to host very Earth-like morphologies, i.e., dunes, flat plains and stable liquid bodies, shaped by a methane-based hydrologic cycle. BSR observations of the large seas of liquid hydrocarbons covering the northern pole of the moon showed strong reflections from very smooth surfaces, strikingly opposed to weak echoes from dry terrains.
The low detectability of reflections from solid ground is a puzzling issue that may be due to specific properties and scattering mechanisms of Titan’s surface or could be an artifact of the implemented signal processing technique. The goal of this activity is to process some of the Cassini BSR observations of Titan’s solid terrains with a mindful spectral analysis of the raw data, providing a quantitative assessment of the effect of simple signal processing parameters, i.e., integration time and count time, on the detectability of weak surface echoes.
Uploaded: 5 Mar 2024/GB
Code: LT24CABRTS
In the context of planetary exploration, radiometric tracking is often aided by the processing of optical images. While this methodology greatly increases the scientific return of space missions, it also increases the complexity to the orbit determination procedure, as the estimated trajectory of the spacecraft becomes a baseline for the estimation of planetary-fixed reference frames and surface features. Contrarily, optical-based navigation can be employed when using well-known features from asteroids or planetary surfaces.
The aim of this thesis is to create algorithms to read and process images acquired by past deep space missions, especially MESSENGER, from the Cartography and Imaging Sciences Node of NASA. The work will consist in developing a pipeline to extract label information from pictures metadata to query and evaluate potential correlation between images, often necessary to support the estimation of the planetary rotations. Desirable skills include Python programming, but training will be provided. This works is relevant in the context of current and future planetary exploration missions in the Mercury system, such as the BepiColombo MORE investigation of the planet.
Uploaded: 11 Mar 2024/AT
Code: LT24DPOPTP