Further development of the Delft Deployable Space Telescope (DST) was needed to solve for defocus due to thermal expansion. This thesis focuses on implementation of stray light design methodology on the deployable baffle to provide a more stable temperature environment. This methodology utilises various baffle shapes and the arrangement of vanes to absorb or reflect incoming light to the desired location. The effect on the thermal and stray light performance is analysed, to gather insight to form several baffle concepts. These are put in a trade-off with thermal and stray light performance in mind. The result is a deployable baffle using four vanes which increases the compliance to the defocus requirement by 28% for the visible light version of the DST. The baffle for the thermal infrared DST is a cylindrical baffle with one vane with a 100% compliance to the defocus requirement. The thesis provides the design of the baffle which reduces the defocus and reduces stray light.

Synthetic Aperture Radars (SAR) have demonstrated to be great instruments for space-based Earth observation in the microwave frequency. Metasurface antennas, on the other side, are a new type of planar antennas with a great potential for space applications, as they are compact and easy to produce. Several methods have been developed in the past years addressing one or many parts of the design and applications of these antennas, which rely in more or less measure in locally developed tools. However, some parts of these methods can take a great amount of time to implement, making this process more difficult than it should especially if the user has commercial electromagnetic simulation tools available that could accelerate this process. In this work, different procedures have been adapted to the design of a high-gain SAR anisotropic metasurface antenna for a multi-static Earth observation mission, showing that the proposed methodology produces accurate results.

To mitigate the growth of space debris, it is vital that Active Debris Removal (ADR) is performed in the near future. Since ADR will require robust relative navigation, future spacecraft should be marked with fiducial markers that are robustly extracted from an image taken by a chaser spacecraft. To prevent the restriction of robotic movement and occlusions of features, planarity of these fiducials is desired. While numerous planar fiducials exist, the performance of these systems suffers from pose ambiguities and loss of precision under frontal observations. In order to mitigate these issues, encoding markers have been proposed in literature. These markers encode an extra dimension of information in the signal between marker and sensor, thus increasing the robustness of the fiducial system. However, little research has been done on these encoding markers and existing solutions are hard to manufacture, qualify and scale. This thesis proposes a novel fiducial marker design based on the compound eye of a Mantis insect. The fiducial proposed in this work, the so-called Mantis Marker, is planar and encodes a virtual point in its signal. This virtual point is located at a distance from the marker plane. This makes the marker system mathematically equivalent to a fiducial that uses a protrusion or indentation. This increases pose robustness by an order of magnitude with respect to planar fiducials of the same dimensions, as demonstrated in this thesis. Furthermore, the marker is easy to manufacture, is scalable and has low complexity. Finally, the marker is suitable for pose estimation for robotics and Augmented Reality (AR) on Earth where additional pose robustness is required.

Electromagnetic metasurfaces in recent years have drawn significant attention in the Optics community due to their novel optical properties and miniaturized integration advantages. Since the optical properties of those materials are complex to model and require finer theory than what implied in geometrical optics, systematic integration study of those solutions is not reported in Literature and motivates this research. In previous work, the design of polarization-sensitive spectral filters based on metasurfaces devices and integrated into Bragg reflectors has been reported. The use of such a spectropolarimeter concept may lead to significant miniaturization improvements in Space applications, where launches of small satellites are becoming accessible to not-governmental companies and trending. Typical spectral and polarimetric functionalities are currently integrated with several additional components required for the propagation of light. The metasurface based spectropolarimeter concept operates in a division of focal plane and can be integrated on off-the-shelf CMOS sensors, when opportune factors are taken into considerations, with the use of a single lithographic step. The main difficulty in their use arises from the limited bandwidth dictated by the Bragg reflector and the polarization response of the metasurface, as well as strict requirements of telecentricity to limit angle-dependence at the focal plane. In the present work, we offer novel modeling tools to predict the electromagnetic performance of the device in terms of diffraction and spectral response. We explicit how those tools, in comparison with other approaches like Finite Element Methods, can provide an efficient and physical-based assessment for the design of the spectro-polarimetric filters. We apply then such tools to analyze the diffraction of the filters and the integration of the sensor in a Space Mission for aerosol detection in the VIS and SWIR range, by designing a set of filters able to overcome the bandwidth limitations above mentioned, finally providing simple engineering figures in terms of integration requirements to be considered. The work sets the bases for further improvements, on one side, in the modeling of those structures and on the other side in their integration in complex systems.

The need for higher spatio-temporal resolution Earth observation increases rapidly. To fill this need, the Deployable Space Telescope (DST) project aims to make a light-weight, low-volume deployable telescope. In doing so, the achievable ground resolution is high while the cost per telescope stays low. This allows for the DST to be used in constellations, thus effectively achieving a high spatio-temporal resolution. One of the issues of this design are the relative translation and rotation of the secondary mirror due to temperature fluctuations. This thesis work focused on first finding these movements by identifying the temperature variations of the secondary mirror support structure using ESATAN TMS simulations, and subsequently designing a system to keep these movements within the allowed budgets. The end-result is a novel design in which all displacements are measured by means of 4 Displacement Measuring Interferometers and corrected by means of 4 linear piezo actuators.

The purpose of the thesis was to design a deployable thermal shielding baffle for the Deployable Space Telescope to reduce thermal gradients on the optical elements. As a result of a trade-off, the deployment was chosen to be based on an inflatable structure. The baffle consists of aluminium-kapton booms that form a cylindrical shape, and are rigidised after deployment through overpressurisation. Thermal shielding is provided by a blanket of multi-layer insulation surrounding the cylinder. Numerical analysis has shown that the baffle can withstand expected static and vibrational loads during operations, and preliminary thermal analysis results show that temperatures on the telescope are stabilised.

The Deployable Space Telescope (DST) project aims at producing a competitive telescope by using segmented deployable light weighted optics which reduces launch volume and mass, and thus launch costs. Due to the criticality of heat management to the performance of the telescope, a thermal model had to be built in order to determine the expected temperatures throughout the telescope in orbit. Further, the premature baffle design required a supportive thermal analysis such that its critical parameters could be determined.

The Deployable SpaceTelescope Project was started at Delft University of Technology in 2014. The projectaims to develop an ultra-high resolution Earth Observation telescope with aresolution of 0.25m, but with a much lower mass and volume than its competitorscurrently in operation. In order to meet the stringent mass requirements, adeployable primary and secondary mirror are used. However, it is expected thatthe deployment of the optics will introduce severe aberrations in the system,limiting the performance. This thesis project investigated the implementationof phase diversity algorithms as a method for correction of these aberrationsthat does not add additional mass and complexity to the system. Phase diversityalgorithms originate from the field of ground-based astronomy and are rarelyused in space systems. Even less is known about their behavior in EarthObservation telescopes, which typically suffer from larger aberrations thanground-based telescopes. Also, Earth Observation telescopes image extendedscenes instead of point objects. FORTA, a ray tracing application developed ir.D. Dolkens specifically for simulation of the Deployable Space TelescopeOptics, was used for the simulation of the telescope imaging process. A MATLABtoolbox, developed during this project, was then used for simulation of a broadrange of phase diversity algorithm configurations. These algorithmconfigurations numerous methods from the field of imaging, including aneffective method for mitigating wrap-around effects resulting from theapplication of the Fast Fourier Transform. First, the set of algorithmparameters resulting in the optimum configuration in the context of the DSTproject was determined through a large number of parametric studies. Afterthat, it was found through simulations that by using a novel method for theselection of the subframe to which phase diversity is applied a significantperformance increase could be obtained. An analysis of the open-loopperformance of the algorithm showed that the wavefront error in the exit pupilcould be estimated to within a Root Mean Square (RMS) error of 0.07 lambda_0 inover 75% of simulations, where lambda_0=450nm is the smallest wavelengthaccepted by the panchromatic channel, and that a Strehl ratio (SR) of above 0.8was achieved in over 80% of cases. Through the development of an innovativepost-processing method that exploits a priori knowledge of the expected errorshape, both these percentages could be increased to above 85%. Deconvolutionusing a Wiener filter subsequently resulted in the reconstruction of details ofsmaller than 0.25m, in accordance with requirements. In addition, an analysisof the closed-loop performance was done, in which the wavefront error estimateswere used for iterative control of the active optics. This analysis showed thatfor initial Strehl ratios of higher than 0.6, the method would consistentlyincrease the Strehl ratio to a value of around 0.8 or above. However, after anoptimum was reached the method would diverge again. For the reliableimplementation of phase diversity in a closed-loop configuration, an effectivetermination criterion should be developed. Phase Diversity methods showpotential for implementation in the DST project, and it is recommended thatfurther studies are performed. These studies should focus on making the methodmore reliable through identification of inaccurate estimations, as well as onthe joint implementation of phase diversity with other calibration methods sothat the strengths of phase diversity can be exploited and its weaknessescompensated.

Bottom-up thermal-mechanical design and analysis of a deployable baffle, which serves as a deployable thermal control system for the Deployable Space Telescope. Research being conducted on how to create a stable thermal environment for the mirror support structures so that in-orbit thermo-elastic drift budgets will be met, as well as designing and analysing a feasible deployment system.

This research is focused on the feasibility assessment of a novel technology of metasurfaces in order to design a spectropolarimeter with the thickness of a few micrometers integrated on the detector array. The motivation behind the research is miniaturization of state-of-the-art spectropolarimeters. The requirements for the instrument are derived from SPEXone instrument, as a reference instrument. Beside the miniaturization, two additional requirements are set as a goal: possibility to measure full-Stokes vector of polarization (including circular polarization), and to improve the spectropolarimetric resolution. The reduction in the volume of the instrument is not the main advantage, but also reduction in the number of optical components with respect to the state-of-the-art. A spectropolarimeter with fewer components allows better stability of performances over different external conditions like temperature change, and easier alignment of the whole system.
In recent years the dielectric metasurfaces attract a lot of attention. Firstly, due to its compatibility to CMOS detector technology, which allows integration of thin layers of metasurfaces directly on the detector array, and secondly due to high transmission of the dielectric materials. The metasurface is an array of scatterers with period and size of scatterers smaller than the wavelength. With proper design, the complete control of electromagnetic waves is possible, including amplitude, phase, and polarization at subwavelength resolution. This is convenient because diffraction is not present at that scale. That enables to design optical devices like lenses, waveplates, polarizing beam splitters with similar performances as current technology, but with extreme reduction in thickness. In this thesis, a systematic electromagnetic performance analysis of metasurfaces is presented. Two types of metasurfaces are designed, first acting as a waveplate, and second as a linear polarizer at different spectral wavelengths. Also, a trade-off of the most suitable spectropolarimetric techniques is done, which led to the Division of Focal Plane (DoFP) type of polarimeter. The combination of these two layers of metasurfaces can modulate the polarization state of light in form of the intensity of light, which is measured on detector pixels. It is shown that with this technique, four unique pixels, each with different polarization modulation, are required to reconstruct four unknowns, the Stokes vector, which fully describes the state of polarization of incident light. Furthermore, the spectral information is measured by designing different sets of four pixels to filter out different parts of the spectrum. The result is two-dimensional detector array which measures spectrum in the vertical axis, and spatial information in the horizontal axis. The spatial information in the vertical axis is achieved by implementing the push broom concept of a satellite. Moreover, the important spectropolarimetric parameters like spectropolarimetric accuracy, spectropolarimetric resolution, and operating spectrum range are estimated. Also, a complete overview of the instrument, which consists of a telescope unit, a bandpass spectral filter and the metasurface integrated on the detector array, is shown. In the end, the performance of the complete system is compared with the reference instrument SPEXone, in order to assess the potential of this concept.

In modern society, there is an ever increasing need for high-quality Earth imagery for various applications. This can be broken up into a need for increased spatial and temporal resolution, as well as a necessity for decreased cost of this imagery. The Deployable Space Telescope (DST) was proposed by Delft University of Technology in 2015 and it aims to achieve these goals by deploying the primary and secondary mirror as well as the baffle structure. By deploying these elements, the launch mass and volume decrease substantially compared to state-of-the-art satellites such as Worldview-4, yet achieving similar ground sampling distances. The great difficulty for the mechanical side of the team is deploying these mirrors with sufficient precision in order to arrive at a diffraction limited image with a ground sampling distance of 0.30 m. This thesis has focused on the Secondary Mirror Support Structure (SMSS) of the telescope and it has been investigated how the testing phase of the project could best be initiated. Two prototypes of the essential CORE hinge have been developed and the hysteresis behaviour of these hinges has been experimentally characterised.
Several improvements for the CORE hinge have been proposed. Shear rims were designed in such a way that protection during launch is guaranteed, but their presence is not detrimental during operations. Furthermore, the mid rollers were removed in order to prevent shearing of the metal strips against these mid rollers. Lastly, a material reselection to aluminium was proposed. Other improvements of the Secondary Mirror Support Structure include the selection of cable cutters as the most suitable hold-down-and-release mechanism for the SMSS deployment. A test rationale was developed and it was decided to initiate the DST testing with the development of two prototypes of the CORE hinge in order to experimentally characterise the hysteresis in these hinges when subjected to load cycling. The CORE hinge has never been flown in space, however, it is proposed as a very promising concept for the deployment of optical surfaces, amongst others due to their beneficial hysteretic response. The first prototype that was developed was created by rapid prototyping and served as a proof of concept version. The second prototype was used for the characterisation of hysteresis. Digital image correlation (DIC) was selected as a measurement system. The DIC set-up was capable of capturing the sub-micron displacements in the hinge.
Note: Conclusions are confidential and omitted from this summary

The thesis discusses the design of the secondary mirror support structure for the deployable space telescope. In the thesis the entire support system is considered, including system layout and mirror interface. A selection of hinge concepts were identified and final concepts were selected in trade-offs. The mid hinge was selected to be an integral slotted hinge, while the top and root hinges were selected to be CORE hinges. The concepts for the root and top hinges were worked out in detail to a point that the hinges can be produced and tested. Thermal and launch loads were considered during the detailed design of these hinges. Furthermore, it was investigated what the effect of adding ribbons to the structure was on the response of the system to harmonic disturbances. The results of this thesis can be used to produce a breadboard for testing the secondary mirror support structure, and as a baseline for further design work on the secondary mirror support structure.

In this thesis, the development of a deployment mechanism for a primary mirror of a space telescope is discussed. A mistake has been found in the earlier work on the design of this subsystem, due to which the design is set back to a concept selection phase. A trade-off has been made between several concepts. A simplified thermal model that assessed those concepts shows that none of them will be able to fulfill the thermal requirements. As a result another more complex concept that integrates the deployment mechanisms of the primary and secondary mirror has been developed. Attention has been paid to athermalization, actuator design and the design of the ribbon connecting the primary and secondary mirror. The thesis shows that it is feasible to meet all requirements, except for the one that defines the mass budget, by improving upon the current preliminary design during future work.

Launch costs for high-resolution space telescopes for Earth observation can be reduced when the telescope mirrors are made deployable. However, such a system is subject to optical aberrations that decreases image quality. To counter these aberrations, an Aberration Correction System (ACS) is proposed that uses a deformable mirror (DM) which is calibrated by applying image sharpness optimisation. A stochastic gradient descent algorithm is applied to the output of two image detectors, such that the DM deformation can even be optimised during in-orbit scanning operations, without the need for a dedicated wavefront sensor. The effects of different sharpness metrics and algorithm settings have been analysed. With this novel control method, an average Strehl ratio of above 0.9 and 0.8 can be achieved on the central field and extreme field of the primary detector respectively. Also, in-orbit drift effects can be actively compensated without interrupting nominal operations.

In the search for understanding the formation and evolution of a solar system, terrestrial planets & any exoplanetary systems, the understanding of the evolution & formation of giant planet's play a crucial role. The primary goal is to study the atmospheres, their physical & chemical processes governed by gases, clouds, and hazes. This research focuses on developing a new technique to characterize aerosol particles using a nephelometer. The new forward model is a two-part model, in the first part, an atmosphere radiative model for Saturn & Venus is developed and the polarization internal field is evaluated using Monte-Carlo technique. The second part of the model is to demonstrate the feasibility of the new instrument technique developed in first part using space system engineering approach. The research concludes that the forward model developed could be used to evaluate the internal polarization field of any planetary atmosphere. The feasibility study of new instrument technique for Saturn’s atmosphere demonstrates a possibility to derive the vertical structure up to 2[bar] pressure & for Venus’s atmosphere in all layers.