The design of an optimized retroreflector array for satellite laser ranging (SLR) is critical for enhancing satellite tracking accuracy and providing a passive space segment backup for conventional attitude determination systems. This thesis documents the research aimed at developing an effective retroreflector array for the new TU Delft platforms: Delfi-Twin and the Da Vinci satellite. The goal is to enable SLR measurements via both the International Laser Ranging Service (ILRS) network and the laser communication terminal at Delft University. Following a structured approach, the most suitable array configurations were identified through a Probability of Visibility (PoV) simulation. Consequently, a link budget analysis was performed, coupling the selected arrays with the considered ground stations to define the required retroreflector size to enable SLR measurements. Improvements to the Delft laser communication terminal have also been proposed to enhance its SLR capabilities. Future work will focus on qualifying the acquired retroreflectors and finalising the holder structure for satellite integration.

Ceres is a small dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. In this work, its interior density, interior temperature, crust thickness and crust density are modelled with the aim of determining possible formation mechanisms for the cryovolcanic bright spots on its surface. The results imply that Ceres has a muddy subsurface ocean from which the cryovolcanic material originates.

Surface heat flux, which can be defined as the heat flowing out of the interior of a planetary body, provides important constraints on the present-day thermal state of the lunar interior. Measurements, performed in situ during the Apollo program, and from orbit by Chang’E 1, Chang’E 2, and by the Diviner radiometer instrument, indicate important lateral variations in surface heat flux on the Moon (~5-180 mW/m²). The differences between Apollo 15 and Apollo 17 measurements have been explained by the presence of an anomalous region, enriched in uranium (U), thorium (Th), and KREEP (Potassium, Rare Earth Elements, and Phosphorus) elements, located on the lunar nearside. Previous modeling efforts also identified crustal thickness and thermal conductivity variations as secondary causes for surface heat flux differences. However, detailed explanations for the remaining two estimates and their implications for the evolution of the Moon remain highly debated. Additionally, the structure and properties of this putative KREEP-rich layer have remained uncertain.

Therefore, this study proposes a new global geodynamic model of lunar thermal evolution that includes lateral variability in the distribution of radiogenics, crustal thickness, and thermal conductivity. The present setup is capable of simultaneously explaining the variability between the Apollo 15, Apollo 17, and Region 5 heat flux values, while also providing further constraints on the KREEP layer structure and lunar crustal properties. The research question addressed in this work is: What is the effect of crustal structure (radiogenics, thickness, and thermal conductivity distribution) on 3D thermal evolution models of the Moon?

Here, we model the interior dynamics and thermal evolution of the Moon after magma ocean solidification using the fluid solver GAIA. We investigate the abundance and distribution of radiogenics on the Moon, and how they shape the interior temperature distribution through time. Additionally, we account for a spatially variable crustal thickness, derived from gravity and topography data. We also include a laterally variable thermal conductivity model, derived from porosity data, which we constrain using the nearside-farside differential thermal state of lunar basins. We model and vary the extent of a putative KREEP layer underlying the PKT (Procellarum KREEP Terrane) region. We enrich the KREEP layer and crust in heat-producing elements compared to the mantle, simulating an asymmetrical distribution of radiogenics as an initial condition.

We find that measurably lower heat flux values at the lunar south pole compared to Apollo 15 and 17 require KREEP material to extend at least partly beneath Mare Serenitatis. In this case, the Apollo 15 measurement would be representative of the KREEP region average heat flux, while Apollo 17 would lie on its edge. On the other hand, a smaller KREEP region (<1200 km in diameter) would make the Apollo 17 location representative of non-KREEP terrane, and show heat flux comparable to south pole values. This is incompatible with estimates based on the Diviner Lunar Radiometer Experiment onboard Lunar Reconnaissance Orbiter, although uncertainties associated with these estimates are unclear. Heat flux measurements that will be performed by the NASA CLPS-CP12 mission at Schrödinger crater will provide key information to exclude one of these two scenarios, and thus potentially constrain the extent of the KREEP layer underneath the PKT region.

Our results also show that a laterally variable thermal conductivity helps reduce the interior temperatures, while maintaining surface heat flux distribution unchanged. We find an effective farside crustal conductivity of ~2 W/(mK) (comparable to that of compact anorthosite) to best match the differential basin relaxation constraints, implying negligible effect of a porous megaregolith layer on the thermal conductivity. In the KREEP region, we favour models with effective crustal conductivity below 2 W/(mK), suggesting that lunar volcanic basalts may have an even lower bulk conductivity than the 2.6-2.7 W/(mK) values considered here. This could be due to the porosity of lunar volcanic material, a more complex layering of basaltic eruptions, or the effect of the temperature and pressure dependence of thermal conductivity. Although our model setup is simplified, it provides novel insights on the distribution of radiogenics and crustal properties on the Moon, and shows the potential to further constrain the asymmetrical character of lunar evolution.

Ariel is an ESA space telescope planned for launch in 2029. It is aimed at observing ∼1,000 exoplanets using transit spectroscopy at infrared wavelengths between 0.5-7.8μm, to characterise the chemical composition and thermal structure of their atmospheres. To detect minute flux variations and confidently extract the exoplanet signal, Ariel requires good instrumental flux stability. Moreover, the instrumental response must be monitored through time, and instrumental effects and stellar noise must be estimated and minimised to get as close as possible to the photon noise limit. To do this, Ariel must be calibrated in-flight by observing a set of stellar calibrators, stars whose spectral energy distribution is assumed to be well-studied and constant. This project is aimed at building the stellar calibrator catalogue for Ariel and looking for possible correlations between stellar properties and flux stability. This can also serve as a base study for future space missions other than Ariel. A starting candidate sample mainly including G dwarfs that were observed by TESS is filtered with a three-step procedure using the Lomb-Scargle periodogram and the reduced chi-squared statistic. Assuming an Ariel 3σ flux stability requirement of 100ppm over 6 hours, the defined Ariel Catalogue comprises 581 stars. These are fairly homogeneously distributed over the sky, without periodic variability, and without a large flux excess dispersion. It is found that when selecting the correct effective temperature ranges (5, 000 < Teff < 6, 300K), the probability of finding stable stars is almost constant at 30%. Only the dimmer stars seem to have a higher probability of passing the selection, which is possibly due to the higher noise in the data which makes variability more difficult to identify. Note, however, that the catalogue defined in this study still comprises calibrator candidates. The noise in TESS light curves is probably too high to effectively analyse the stability within the current requirement. So, follow-up observations of these stars with a lower noise are recommended, for instance with PLATO, to greenlight them as final Ariel calibrators.

The Mars Ascent Vehicle will bring samples back from the surface of Mars to its low orbit in 2031. Its preliminary design has been performed by NASA, defining it as a two-stage solid propellant rocket. However, a research gap exists in finding what the optimum solid rocket motors geometries are to bring the Martian samples to a target orbit between 300km and 375km above Mars.
To this extent, the ascent and propellant burn have been modelled, allowing for variation in the geometry of the motors, but also in the launch and separation angles, and in thrust vectoring control. This model has been incorporated into an optimisation, from which a minimum lift-off mass of 343kg was found, 57kg less than required. In the process, 18 thousand different solutions have been found that satisfy all requirements, would the priority shift from the mass of the vehicle to for instance the burn time, or the final altitude.

The dark flight of the meteorite in the atmosphere complicates the estimation of the impact point on the Earth’s surface. The irregular shape of the meteorite affects the aerodynamic forces during the dark flight, which can influence the trajectory of the meteorite. This further complicates the meteorite recovery. Limited knowledge of the aerodynamic properties of meteorite is speculated as one of the major reasons for partial recovery of the meteorites. Therefore, this work experimentally investigates the meteorite aerodynamics during dark flight using a subsonic wind tunnel. The drag coefficient, free fall analysis from 10 km altitude and the rotational aspects were studied using a 3D printed meteorite model. Additionally, the results were implemented in a dark flight code to study the influence of these parameters for a hypothetical meteorite fall. This study proved that aerodynamic forces are very crucial in the meteorite dark flight and strongly influences the meteorite trajectory.

Within a Protoplanetary disk (PPD), planets form from micron sized particles, but what are the processes taken for planet formation? How does the evolution of micron sized particles via settlement and coagulation lead to the gigantic planets as the ones in our Solar System? This thesis explores the planet formation process of pebble accretion which is a planet accretion model involving the accretion of smaller bodies onto larger planetesimals. The evolution of micron sized particles into millimetre – centimetre sized pebbles are discussed. These particles will experience growth via settlement and coagulation, radial drift before acting as reservoir for planet cores to accrete and grow from. From the results, it is found that planet formation via pebble accretion is more efficient in the outer regions of the Solar System, where pebble formation was favoured and resulted in smaller inner planets and larger ice giants.

Supersonic plumes consistent of water vapor and ice particles have been observed by the Cassini spacecraft when flying over the tiger stripes of Enceladus at the south polar terrain of the satellite. Measurements of the salinity of the plumes (0.5-2%) and the size of the emitted particles, indicate a subsurface liquid ocean beneath the crust of ice. The vent temperature of the plumes were measured to be relatively high (170-210 K) compared to the cold surface temperature of Enceladus. The mass flow, velocity and particle size show a wide range of possible values, whereas the solid fraction is estimated between 7 - 20 %. Here we demonstrate a fluid dynamics model that accounts for nucleation, particle growth, wall accretion and sublimation and the viscous interaction with the walls. The channels behave as converging-diverging nozzles, which form supersonic plumes due to a pressure difference between the reservoir and the exosphere. The geometry of the channel, the reservoir conditions and wall interactions are studied to reproduce the characteristics of the plumes observed by Cassini. From a parameter study performed on the crevasse properties we find that the velocity and the solid fraction increase with the expansion ratio, whereas the exit temperature is inversely related to the expansion ratio. The interactions with the walls reduce the mass flow in the channel and start condensation earlier in the channel, this increases the solid fraction, particle size and velocity and reduces the exit temperature. The particle size is dominantly dependent on the length of the channel, large particles (75 *10(-6)m) must originate from up to a kilometre below the surface, while smaller particles (3 *10(-6) m) can originate from 150 m below the surface. The channel requires an expansion ratio close to Dthroat/Dexit = 4, to generate the observed exit temperature <210 K with velocities up to 950 m/s and a solid fraction ranging from 0.07-0.2. The minimum width of the channel needs to be in the order of meters to withhold the channel from freezing up within days and a liquid reservoir at a temperature near triple point is most probable to agree with the observed exit temperature and velocity.

This thesis aims to improve our understanding of the role of ices in planet forming discs, known as protoplanetary discs. Computer models of such discs have been used extensively by the community to understand and predict the observational data. It has always been a challenge to observe ices in the discs and their optical appearance is largely omitted in the disc models. This is due to the complexity and high computational power requirement for computing the opacities while the chemical composition and abundance change at every point in the disc. This work is focused on providing a computationally efficient way of estimating the optical properties of ices in the state-of-the-art Protoplanetary Disk Model (ProDiMo). Although observations of ices are rare, some observations particularly for the 3 micron water ice feature are available. These have been studied by means of different radiative transfer disc models, however, the effect of the position-dependent ice opacities on the physico-chemical disc structure has not been considered. In this work, it is found that the optical properties of dust depend on the ice composition, the ice abundances and how the ice accumulates on the refractory dust grains. It is shown that using a pre-calculated opacity grid and performing interpolation between these grid points provides an accurate and computationally efficient estimation of position dependent ice opacities in protoplanetary discs. Further, it is found that the inclusion of chemically consistent ice opacities calculation in the disc model does not have a significant effect on the physico-chemical structure of the disc. However, the appearance of the disc changes significantly. Dark bands appear in disc images at wavelengths corresponding to ice absorption features. These features are stronger when the thickness of the ice layer on the refractory dust grains is assumed to be constant but weaker when the ice/refractory volume ratio is assumed to be constant. The predicted disc spectra are analysed considering the spatial resolution offerred by spectrographic modes of Near-InfraRed Spectrograph (NIRSpec) onboard James Webb Space Telescope (JWST), expected to launch in 2021. This shows that the ice features can be observed, particularly when the disc is seen against a distant background source (silhouette discs). Thus, silhouette discs are promising observational targets to study ices in discs.

This thesis studies single events (SE) in an SRAM from the identical satellites Sentinel 2A and 2B, in order to find links between SE, space weather, satellite operation and device properties from time and position of event occurrence. A study of theory on single event rate prediction and space radiation environments lies the foundation for the subsequent data analysis. A focus is placed on aspects relevant with the Sentinel 2 satellites. Using Python libraries, raw satellite housekeeping data is pre-processed to make available time and place of event occurrence. Then, a moving-average filter is applied to reveal the long-term behavior of SE position and rate. The filtered SE rate data shows a linear trend, attributed to solar cycle and device degradation. Further, there are features attributed to memory hot spots, South Atlantic Anomaly (SAA) semi-annual behavior and geomagnetic storms. Future event rate data and data on affected memory addresses will help to further distinguish these influences. Filtered event positions track the drift of the SAA, but contain suspicious differences between the satellites. These are attributed to memory hot spots as well. Spectral analysis reveals that the only short-term influences in the unfiltered data arise from the orbits of the satellites. Within the SAA, event rate is similar for eclipsed and sunlit, but outside of the SAA, event rate is approximately twice as high in sunlit. This difference is currently unexplained.

As part of the New Earths in the Alpha Cen Region (NEAR) experiment, VISIR, an imager and spectrometer for the mid-infrared at the Very Large Telescope (VLT) of the European Southern Observatory, will be soon upgraded to improve its performance in terms of high contrast and sensitivity for the detection of Earth-like planets in the Alpha Centauri star system, the closest to the Sun. Part of the VISIR upgrade consists in a novel chopper system based on the Dicke-switch concept to suppress the excess low frequency noise (ELFN) suffered by the detector array. The ELFN is a form of temporally correlated noise and can be mitigated by modulating the incident light at high enough frequency. The other main challenge of the NEAR experiment is the need of high contrast to image the circumstellar environment, and it will be achieved with the implementation of an annular groove phase mask (AGPM) coronagraph for the suppression of the starlight. The main goals of the thesis project were the validation of the Dicke-switch chopper systems to assess its ability to mitigate background level and ELFN, and the characterisation of the performance of the AGPM coronagraph in terms of null depth and contrast level. The first part of the laboratory characterisation of the Dicke-switch chopper system focused on the verification of the radiometric flux level achievable by its internal blackbody unit and by the so called artificial sky, a cold blackbody needed to reproduce the background level typical at the VLT, where the combined sky and telescope thermal radiation is the same as the one of a greybody at 280K and 10% emissivity. After the completion of the radiometric tests and mitigation of parasitic light effects caused by reflection of internal and external thermal radiation, the tests to validate the ability of the Dicke-switch chopper system to remove background level and suppress the ELFN started. The obtained results confirm that the Dicke-switch chopper system mitigate the ELFN as done also with pseudo-chopping. This was verified also for large offsets between the flux level of internal blackbody unit and artificial sky. Similarly, the characterisation of the AGPM coronagraph started with the preparation of the laboratory setup, in particular design of the optical setup, alignment of all the optical components and measurement of the optical quality of the system to limit residual aberrations and vignetting. The results of the coronagraphic tests revealed that the two candidate AGPMs for the NEAR campaign, both optimised for wavelengths between 10 and 12.5 μm, are not able to provide the required contrast level and null depth. On the contrary, an older AGPM, spare part of the one currently mounted in VISIR, and thus optimised for wavelengths between 11 and 13.1 μm, provided better coronagraphic performance, and even though it is still not compliant with the requirements, at present it represents the baseline for the NEAR experiment.