UV excited mineral fluorescence observations allow for a potential low-complexity, low-cost method for identifying regions of interest during Martian in-situ observations. However, the effect of low temperature conditions analogues to Martian night-time conditions on fluorescence and phosphorescence behaviour has not been previously researched for minerals relevant for Mars science objectives. Additionally, previous Mars fluorescence observations have mainly used long-wave UV excitation. This research investigates how UV-induced visible mineral fluorescence and phosphorescence signal of Mars relevant minerals are affected by temperatures analogous to Martian night-time conditions, and how these responses may be characterised using an RGB camera-based optical system.

A selected set of Mars-relevant and fluorescent mineral specimens was observed under short-, medium- and long-wave UV excitations (UV275, UV310 and UV365, respectively) using a MAHLI analogue optical system. Observations were acquired at room temperature and at low-temperature conditions using a liquid-nitrogen cooled experimental set-up. The fluorescence response was characterised in terms of detectability, camera specific radiance and chromaticity, and phosphorescence behaviour. As the camera-based RGB data represent integrated CMOS detector responses, the measurements were interpreted as calibrated camera responses.

The results indicate that the excitation wavelength strongly affects fluorescence detectability. Several mineral components were visible under multiple UV wavelengths, whereas others were only detected under specific excitation conditions. Therefore, multi-wavelength UV excitation provides additional information compared to a single long-wave UV observation. Cooling generally increased sustained fluorescence radiance in the robust dataset, although mineral-, activator- and wavelength-dependent exceptions remained prominent. Lowering the temperature of minerals to Martian night-time temperature conditions affected chromaticity data in selected specimens, but most chromaticity shifts remained within the same broad visible colour class and no systematic chromaticity-shift direction was observed across the complete dataset. Phosphorescence showed a stronger dependence on mineral component and temperature: observations at low temperature conditions increased the detectability, initial post-excitation radiance signal or visually determined duration of phosphorescence for several specimens.

The results indicate that RGB UV fluorescence imaging using an enhanced MAHLI analogue can increase the detectability of selected fluorescent and phosphorescent mineral components under Martian night-time analogue conditions using short-, middle- and long wave excitation sources. However, the method is not suitable for definitive mineral, activator or defect identification without spectrally resolved follow-up measurements. Its strongest application is therefore an in-situ triage method for identifying spatially resolved fluorescent regions of interest on the Martian surface that may subsequently be selected for more detailed and costly spectroscopic or geochemical analysis. ... Read more

Continuous monitoring of Terrestrial Water Storage is essential for detecting floods and droughts. This study assesses whether Swarm gravimetric observations can support abnormal-event detection during the GRACE/GRACE-FO data gap. A two-stage methodology is applied across 16 regions: a climatological model estimates the expected GRACE/GRACE-FO signal from trend and periodic components, while an outlier-detection model combines this estimate with Swarm data to classify events. Design choices are evaluated through an Individual Effect Analysis. Results show strong regional variability, driven by event availability and gravimetric signatures. Swarm provides useful auxiliary information, but some basins require region-specific features or models to achieve reliable detection. ... Read more

The melting Greenland Ice Sheet is one of the major contributors to present-day global sea-level rise. However, its long-term evolution remains uncertain due to the complex interaction with the Earth's deforming crust, a process known as Glacial Isostatic Adjustment (GIA). To date, the influence of lateral variations in mantle properties on this interaction, and consequently on the evolution of the Greenland Ice Sheet, has not been investigated. In this thesis, an ice-sheet model is coupled to a three-dimensional solid Earth model to simulate the evolution of the Greenland Ice Sheet until the year 2500. The results show that bedrock uplift partially mitigates ice loss, reducing the projected contribution to global sea-level rise under a high-emissions scenario by approximately 4%. Although the three-dimensional Earth model produces substantial regional differences in bedrock uplift compared with simplified Earth models, its effect on the total contribution to global sea-level rise is limited. Incorporating GIA into projections of the Greenland Ice Sheet therefore remains essential for realistically simulating its long-term evolution, while complex three-dimensional Earth structures provide only limited added value over simplified GIA models for estimating the total sea-level contribution. ... Read more

As fragments floating through space, asteroids contain a lot of information regarding the history and development of our universe. As such, for a long time humans have been fascinated by meteor entries into the atmosphere, and have devised large scale camera networks to track the entries of such meteors. Despite the effort put into these camera networks, this approach to detecting meteors has serious limitations regarding its effectiveness during daytime or during cloudy nights as this prevents the fireballs from being visible. As such, there is interest in expanding these detection networks with infrasound sensors, highly sensitive microphones which can detect the low frequency sound that propagates from a meteoric entry shockwave.A lot is still unknown regarding the effective implementation of such infrasound sensors into a detection network. As such, this study investigates three important aspects of such a potential implementation, being the detection pipeline/algorithm, methods for reducing the wind noise, and the layout of a potential future network.Using publicly available infrasound data and meteor detections, a pipeline was developed for detecting meteoric entry signatures in this data. Although some likely meteor signatures were found within this data, the true detection rate is only around 3%-4% of the events included in this analysis, with a similar number of false positive detections being flagged.To achieve better detections in a properly integrated network, two different approaches have been tested for reducing wind noise at the infrasound sensor. Both the tested porous hose filter and the fabric dome filter successfully reduced the measured noise level by $10$ to $15$ dB between $10$ and $30$ Hz. At slightly higher frequencies, the porous hose filter started to perform worse as a filter, and began introducing artifacts into even coherent signals.Lastly, the layout of a potential infrasound network within the Netherlands has been investigated. For this network, three infrasound sensors would be placed throughout the Netherlands, with stations guaranteed at Delft University of Technology and Tilburg, and a third sensor at a yet undetermined location. From the available candidate locations, the Elburg location was found to provide the most versatile detection network for future research into infrasound detection of meteors.
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In 2025 ESA has started bistatic radar experiments between Mars Express (MEX) and the ExoMars Trace Gas Orbiter (TGO), to make the first attempts to localise areas of significant water at locations near the equator and at mid to low latitudes.

Building upon previous work, in this thesis an improved model to simulate bistatic reflectometry measurements between MEX and TGO was created. Moreover, at Earth GNSS-R (Reflectometry) measurements have been employed for several years, and concepts from GNSS-R were studied in this thesis and have been implemented into the model.

The simulated measurements were compared with measured data and with the model of the previous work. Measurement parameters, including signal polarization, s/c pointing, and permittivity were also investigated and the findings of this thesis show the effects that these parameters have on the received signal. Finally, future measurement opportunities were also investigated.
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There is a strong coupling between the interior, surface, atmosphere, and magnetosphere of planetary bodies which contains fundamental information about their evolution and dynamics. However, sparse observations beyond Earth limit the ability to isolate faint signals from background variability. This thesis establishes a scientific and engineering framework to address these limitations with a spatially and temporally distributed sensor array. The study maps mission goals to science and payload instrumentation requirements for Earth and planetary scenarios via a Science Traceability Matrix. The methodology includes performance and cost modeling with multi objective evolutionary algorithms to produce non-dominated constellation architectures. Furthermore, it develops a general model of spacecraft reconfiguration dynamics by exploiting the non-spherical gravity field of the central body, with results on propellant/time trade-offs. This work contributes to the "PULSAR" NASA Innovative Advanced Concepts proposal and was conducted within the NASA JPL Robotics Modeling and Simulation group. ... Read more

Mapping shallow subsurface water (ice) on near-equatorial Mars is critical for future (manned) exploration, yet existing research shows poor correlation, leaving its presence debated.

This thesis assesses dual-spacecraft Bi-Static Radar (BSR) measurement feasibility at Ultra High Frequency, providing near-global coverage ideal for comparison with gamma/neutron spectrometry hydrogen maps. The Mars Express lander relay antenna transmits a continuous signal probing a few metres into the subsurface (shallow depths which cannot be mapped by conventional low-frequency radar). The ExoMars Trace Gas Orbiter receives the echo, whose amplitude directly reflects permittivity variations induced by compositional changes, e.g. water (ice) deposits.

Models were created to optimize measurement planning and simulate the received power spectrum against BSR data. The current match is limited, reflecting the method’s novelty, and surface composition is yet to show a strong signature. However, after calibration, resolution increase and improving direct signal, seasonal and polarization effects modelling, reliable detections appear possible. ... Read more

With the increasing amount of plastic debris in Earth’s waters, concerns about its impact on aquatic ecosystems continue to grow. While satellites like Sentinel-2 have demonstrated the value of remote sensing, the lack of a dedicated mission limits detection to large-scale plastic accumulations and fails to capture their dynamic behavior. This thesis investigates the feasibility of using deployable optics in Very Low Earth Orbit (VLEO) to improve spatial and temporal data on marine plastic. Focusing on system volume—critical to mission viability—and building on the Deployable Space Telescope under development at TU Delft, satellite volume was modeled through Monte Carlo simulations. A volume envelope as a function of orbital altitude was generated, accounting for design and environmental uncertainties. Compared to a traditional Low Earth Orbit telescope, the VLEO concept achieved an 88% reduction in volume. This significant improvement highlights VLEO’s potential for advancing Earth observation missions across various domains. ... Read more

This work presents a kinetic Monte Carlo model to simulate noble gas retention in amorphous solid H2₂O–CO2₂ ice mixtures under varying thermal conditions. Calibrated with experimental temperature-programmed desorption data and temperature–density relations, the model enables long-term simulations in small (~150 nm) ice grains. It shows efficient noble gas retention at ≤30 K, with significant loss near 40 K. Krypton fractionation occurs mainly in ices formed at these warmer temperatures. Using protosolar gas abundances, the model reproduces the noble gas composition measured in comet 67P/Churyumov–Gerasimenko. Results suggest the comet’s bulk formed near 40 K, while its icy grains may trace back to colder (~10 K) presolar reservoirs, preserving signatures of both local and interstellar environments. ... Read more

Free-space optical communications on board high-altitude platform stations (HAPS) promises commercial upside for supplying internet connectivity to regions underserved by space constellations. However, platform vibrations and stringent hardware constraints make pointing, acquisition, and tracking (PAT) of optical links difficult to implement. This work investigates the effectiveness of a cascaded control architecture for the combined actuation of a coarse pointing assembly and fine-steering mirror for PAT between HAPS and LEO spacecraft. The laser communications hardware and platform dynamics are simulated in detail, followed by a systematic control design using H∞ optimization. An Extended Kalman Filter combining recorded light measurements from the target and trajectory propagations provide the system with continuous pointing input. Results show that the cascade control architecture can
reject disturbances up to 300Hz in tracking and correct pointing errors up to 40mrad in acquisition. The EKF output accuracy significantly degrades after 15 seconds due to GNSS antenna instability caused by the bending of the HAPS air frame.
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JUICE will measure tidally-induced variations in Ganymede's gravitational field with unprecedented accuracy. Previous research focused on studying tides with a spherically-symmetric interior allowing to constrain the mean shell thickness and subsurface ocean. The presence of lateral variations in the interior alters the tidal response and produces additional signals. This research investigates whether JUICE measurements will be precise enough to constrain possible lateral variations in Ganymede. The structure of Ganymede's ice shell is crucial to the question of habitability, since it influences the process of tidal heating and the transport of heat and material in the interior. This research uses simulated range and Doppler observations during JUICE's orbital phase, to obtain the expected uncertainties in measuring the tides and compares them to the expected signals for a laterally heterogeneous Ganymede model. Results indicate that JUICE could detect zonal lateral variations of degree 1 and 2 if their amplitude is at least ~5% ... Read more

The traditional approach to space mission design considers deterministic dynamics, relying on a Guidance, Navigation and Control (GNC) system to manage uncertainty dispersions. To simplify the iterative process of trajectory design, reduce the burden on GNC, and increase mission safety, this thesis investigates the use of uncertainty propagation to robustify a deterministically-optimal atmospheric entry trajectory. A hybrid Gaussian Mixture Model-Polynomial Chaos Expansions method is optimised and used to generate analytical expressions of the entry corridor statistics as a function of 16 uncertainty sources and five decision variables. These expressions reduce the design space and directly handle stochastic constraints, simplifying the subsequent optimisation. The method is validated on the HORUS-2B vehicle and reference trajectory, widening the entry corridor margins to 2-sigma bounds with errors in the order of 2%. The output of this thesis is a generic stochastic optimisation methodology that is more efficient than traditional optimisation with Monte Carlo simulations.

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Hypersonic glide vehicle trajectory optimization requires generating complete reachable footprints for mission planning under strict path constraints. Current methods face limitations including equilibrium glide assumptions, fixed angle of attack profiles and incomplete footprint coverage requiring re-optimization for each target direction. This work presents the first reinforcement learning approach for complete global footprint generation with dual control authority (bank angle and angle of attack) on a rotating spherical Earth model including direct target point guidance and no-fly zone avoidance. The trained policy generates footprints for any location on Earth while incorporating full three-degree-of-freedom dynamics including Coriolis effects and control rate limitations. All trajectories satisfy operational constraints including dynamic pressure, g-load and temperature limits. The policy learns purely from the objective to maximize range in every direction without pre-designed control profiles. Based on the Soft Actor-Critic algorithm, optimal control strategies are learned directly from environment interaction. Large-scale Monte Carlo validation with 100 million randomly sampled trajectories confirms the learned policy discovered the boundaries of the reachable domain, with the reinforcement learning footprint exceeding the Monte Carlo footprint by 5.1% in footprint area. The framework provides precision target guidance to arbitrary global coordinates and allows for no-fly zone avoidance. ... Read more

Traditional interplanetary orbit determination relies on Earth-based radiometric tracking, for which demand has increased in recent years and is projected to rise further in the future, resulting in oversubscribed ground station networks. Meanwhile, autonomous operations are desirable for faster response times to off-nominal events.

This work investigates the use of celestial navigation from asteroid beacon observations for the cruise phase orbit determination of an exploration mission to the main asteroid belt.
Using covariance analysis, the expected performance of celestial navigation is evaluated during the cruise phase, studied for its sensitivity to the model parameters and compared to traditional radiometric tracking. Under the high dynamical uncertainty associated with solar electric propulsion, beacon navigation yields comparable formal uncertainties to the baseline radiometric tracking setup for trajectory segments within the main asteroid belt. Beacon-augmented orbit determination could therefore potentially reduce the required tracking time, while achieving similar cruise phase performance. ... Read more

High-mass stars are one of the main drivers that shape the galaxy. Understanding the process through which they form is therefore of the utmost importance. This process, however, is not yet fully understood. Contributing to this field, the ALMAGAL survey has studied over 6000 star-forming regions with a higher resolution than any other survey before. On one hand, this data will help scientists study these obscure regions and draw a clearer picture of the high-mass star-formation process. On the other hand, the sheer volume and complexity of the data produced by this survey is far too great for conventional methods to handle swiftly.

This thesis therefore explores the use of unsupervised machine learning (ML) methods to cluster astrochemical spectra from the ALMAGAL survey. The aim of this thesis is to explore which models are best suited for the task, and to use the resulting clusters to establish a chemical evolutionary sequence for high-mass star-forming regions.....

https://github.com/ javialonso05/MSc-Thesis ... Read more

Isidis Planitia is the third-largest impact basin on Mars, located on the north-south dichotomy boundary. It is marked by major geological events that have occurred both globally and regionally. The basin shows two distinct faces. The first is the presence of a high-density subsurface mass concentration, the strongest on Mars, outside of the major volcanic provinces. The second is a clustering of kilometre-scale pitted cone chains of unknown origin, hypothesised to be of volcanic, glacial, or sedimentary origin. This thesis investigates whether and to what extent the subsurface structure of Isidis Planitia controls the surface formation of the pitted cones.

To investigate the interior structure, this thesis combines topographic and gravitational data to construct subsurface models. The models are constrained against observed gravitational anomaly to fit plausible layer geometries and densities. The best-fit model is used to assess the basin’s thermal and stress conditions. The relationship between this subsurface structure and the distribution of pitted cones is then evaluated by correlating with both surface and interior features.

The best-fit structure contains a sedimentary layer that is significantly thicker than previous estimates, at approximately 1.3 km. It also contains a central melt sheet (combined with lava deposits) up to 19 km thick, extending across the plains. Most importantly, the model requires a large volume (approximately 1.7 x 10^6 km³) of mantle-like, high-density materials in the inner basin. This element reaches the near-surface and is identified as a significant plutonic intrusion. The pitted cone distribution shows a poor direct correlation with this subsurface, but aligns strongly with the surface topography, conforming to pre-existing wrinkle ridges. Two distinct sets of wrinkle ridges are observed, with the latter one linked to pluton-driven deformation and subsequent cone emplacement.

Findings support the formation of pitted cones as volcanic rootless cone analogues, resulting from the interaction of a lava deposit with near-surface volatiles. The lava deposit is likely sourced in the north-west, flowing out to the north-east and south-east. The evidence suggests the source is located on the Syrtis Major Planum complex, or derived from the basin floor linked to the plutonic intrusions. Although limited by the available topographical and gravitational data, this first complete synthesis of Isidis Planitia is capable of explaining all its key characteristics in a coherent timeline.

Related dataset 4TU.ResearchData: https://doi.org/10.4121/7f02991f-daac-44c4-8f86-1deb5236b1ec ... Read more

The Earth’s lunar-distance magnetopause is a highly dynamic boundary. Its position plays a key role in shaping weather events within the magnetotail and other space-weather phenom- ena. Statistical studies of the magnetotail require the identification of magnetopause crossings from spacecraft observations to study its dynamics. However, current detections have some shortcomings. Detecting magnetopause crossings can be time-consuming with rule-based methods and manual inspection, especially at the lunar distance due to its variability. Recent automated classifiers do cover larger datasets, but often miss the dynamic nature of the mag- netopause, due to their coarse timing and limited number of detected events. This limits the usability of these datasets for detailed studies of magnetotail dynamics. This thesis addresses these challenges by developing and evaluating machine learning ap- proaches for detecting magnetopause crossings in the lunar-distance magnetotail using AR- TEMIS mission data. First, a gradient-boosted decision tree is used as a baseline, trained to classify magnetosheath and magnetotail samples. Afterwards, a double masked autoen- coder (MAE) Transformer is introduced. This model uses a reconstruction-based method to detect changes in plasma regimes and shifts from the magnetotail to the magnetosheath and vice versa. Both models are trained and validated using a labelled dataset, combining ion spectrograms, plasma moments, and a list of known magnetopause crossings. The results show that the MAE Transformer achieves higher precision with similar recall, and improves timing accuracy compared to the baseline. The MAE transformer is applied to twelve years of ARTEMIS P1 and P2 data, detecting around 3000 magnetopause crossings. The spatial distribution of these crossings matches well with empirical magnetopause models, and a clear correlation to the solar cycle is observed. Outliers in the detected crossings are linked to solar and geomagnetic activity. ... Read more

This thesis presents a methodology to characterize the interior structure of Ganymede, Jupiter’s largest moon, through a joint Bayesian inversion framework that integrates gravity, magnetic induction, tidal, and libration observations. The motivation arises from the growing scientific interest in icy moons, which not only provide insights into Solar System evolution but also represent promising candidates for habitability due to their subsurface oceans. Ganymede stands out as the largest moon in the Solar System and the only one known to possess its own intrinsic magnetic field. It is also believed to host a subsurface ocean beneath its icy crust, making it an interesting target for scientific exploration. However, much of its internal structure remains uncertain. The upcoming ESA’s Juice mission will carry out detailed observations of the moon through a series of flybys followed by an extended orbital tour, delivering high-precision data that will help constrain Ganymede's structure.
This work addresses the challenge of constraining Ganymede's interior structure using multiple datasets - gravity, magnetic induction, tidal, and libration observations - each sensitive to different interior parameters and affected by parameter degeneracies. We first perform a global sensitivity analysis to identify how each observable relates to specific interior properties. Our model assumes a five-layer spherical structure comprising a metallic core, silicate mantle, high-pressure ice, liquid salty ocean, and outer ice shell. The sensitivity analysis shows that magnetic induction is most sensitive to ocean thickness and composition, tidal displacement to ice shell thickness and rigidity, and libration amplitude to shell rigidity. Degeneracies also emerge, such as between shell thickness, ocean density, and shear modulus, highlighting the need for a joint inversion approach.
The Bayesian inversion is carried out progressively. Starting with Ganymede’s moment of inertia, we constrain the core and mantle but leave the hydrosphere largely unconstrained. Including magnetic induction data substantially improves the estimation of ice shell and ocean thicknesses, while the real part of the tidal Love number k₂ refines constraints on the densities of the ice shell and ocean and enables inference of ocean composition. These observations also provide information on the rigidity of high-pressure ice and the compressibility of interior layers. Finally, the combination of moment of inertia, magnetic induction amplitude, and both the real and imaginary parts of k₂ offers constraints on the viscosities of the ice layers, related to the tidal dissipation within Ganymede.
Beyond advancing our understanding of Ganymede, this study demonstrates the effectiveness of joint Bayesian inference for the characterization of planetary interior.This framework contributes to the scientific preparation for the ESA's Juice mission, identifies the most critical measurements to break degeneracies in interior model parameters, and can be extended to other icy moons, such as Europa and Enceladus, where spacecraft data will provide similar observational constraints. ... Read more

The origin of the Martian dichotomy is subject to question and no substantial evidence exists. Some surface and interior features that are not visible in, e.g., topography data, can show up in gravity data. Therefore, this research inverts gravity data to find a crustal and mantle global density model. Previous research performed a one-layer inversion, assuming equal mass in all columns. Also, missions like InSight do not provide global interior information, but only at the landing site. The aim of this research is to provide a global density model of both the Martian crust and upper mantle. The inversion is performed using a weighted, regularized least-squares algorithm. The gravity input consists of the residual between the MRO120F data set and the state-of-the-art gravity field model of the TU Delft. The design matrix is built using Green’s functions, which define the influence of a mass element in all different directions on a measurement point. Using this least-squares algorithm, three different methods for inversion are used. The separate two-layer inversion, the combined independent two-layer inversion and the combined dependent two-layer inversion. All three inversion methods are performed on synthetic planets as well, for verification purposes. By performing all inversions on the synthetic planets, it was found that the combined independent two-layer inversion results in a strong decoupling of short and long wavelength signals, but is not able to attribute gravity signals to different features in the crust and mantle. The combined dependent two-layer inversion does lead to a result that shows decoupling of crust and mantle features. The hypothesis is that adding different gravity components to the combined dependent two-layer inversion will further increase its accuracy. The results of the inversion methods applied to Mars are in agreement with existing research in terms of standard deviations of the crust and mantle density anomalies. The maps were also analysed geologically, where the most important conclusion is the evidence of potential impact basins in the north polar region. These can be evidence to accept the several impact theory for the origination of the Martian dichotomy. Increasing the resolution and refining the third inversion method with multiple gravity components will increase the potential of gravity inversion to define geological features of Mars. ... Read more

This thesis investigates how variations in the Earth-Sun distance influence global temperatures, by comparing a simplified model of the solar system with an existing paper from V.V. Zharkova, claiming that increasing temperatures can be explained naturally. Over a 5000-year period, numerical simulations including planetary gravitational influences, solar inertial motion, and Milankovitch cycles, this study looks at distance variations and Earth hemispheric differences in solar intensity due to albedo differences, to asses this statement. The result shows that while orbital mechanics influence the global temperature, Their role is minimal. It should see a slight decrease in temperature, and thus V.V. Zharkova’s research does not represent the actual situation. This offers valuable insight into the relationship between the Earth's orbital mechanics and climate. However, further research into the accuracy of the model is required. ... Read more