Mars entry guidance faces a critical challenge: navigating hypersonic velocities within the thin atmospheric layers (120 – 45 𝑘𝑚 altitude) while balancing conflicting objectives of precision targeting, thermal survival, and structural integrity. This study addresses a core research question on a successive convexification algorithm that enables precise trajectory optimization for Starship’s hypersonic glide through the upper atmosphere of Mars while enforcing hard physical constraints such as heat flux, g-load, equilibrium glide and dynamic pressure. By formulating such successive convexification - based framework, the inherently non-convex entry problem is decomposed into iteratively refined convex sub-problems, enabling computational tractability under Mars’ variable CO₂-rich atmosphere. The guidance architecture integrates bank angle modulation for lift vectoring and angle-of-attack adjustments for thermal management, optimizing energy dissipation while mitigating heating spikes and aerodynamic stress.

Simulations demonstrate that the collocation discretization strategy used ensures trajectory adherence within the entry corridor, achieving terminal positioning errors below 3 𝑘𝑚 at 45 𝑘𝑚 altitude. The algorithm’s robustness is validated under ±10% dispersions in initial velocity (4.3 𝑘𝑚/𝑠) and flight-path angle (−15°) from a parking orbit around the planet, with heat flux, dynamic pressure, and g-load profiles remaining within mission-critical limits. Sensitivity analyses reveal that atmospheric density uncertainties induce predictable deviations compensated by rapid convex optimizations. These results align and improve on previous NASA mission data.

The study bridges theoretical convex optimization with operational reality, demonstrating that modern computational guidance outperforms legacy predictor-corrector methods in handling nonlinear dynamics and path constraints. By extending the convex framework with adaptive trust regions and sequential convex programming, the proposed method reduces terminal errors by 40% compared to state-of-the-art approaches (Mars 2020). This advancement not only enhances Starship’s capability to deliver crewed and cargo payloads to predefined Martian coordinates but also establishes a foundation for integrating the hypersonic glide phase with the subsequent powered descent phases. As humanity strides toward sustained Mars exploration, this work underscores the viability of successive convexification as a paradigm for achieving precise atmospheric glide through the Martian atmosphere.

Rocket Lab has recovered the first stage of its dedicated small satellite launcher Electron twice by means of splashdown. The ability to reuse the entire first stage can reduce production cost at the current launch frequency and enable a higher launch rate. To lower the launch cost further, Rocket Lab is developing Mid-Air Recovery system for the first stage of the Electron. The research objective of this thesis is to develop a simulation tool for analyzing the launch performance of the Electron rocket and its first-stage recovery, involving mid-air recovery using an air-ram parachute and splashdown recovery using an unguided circular parachute. For the ascent phase, a two-stage rocket Simulink model is developed that implements quaternion representation of six-degrees-of freedom (6-DOF) equations of motion for custom variable mass in the Earth-centered Earth-fixed (ECEF) reference frame to simulate ascent trajectories. Another Simulink model is created to simulate the ballistic trajectory of the first stage after separation using quaternion representation of 6-DOF equations of motion for constant mass in the ECEF reference frame, particularly when first stage recovery is not implemented. It was found that he additional mass, which is required to transform the Electron’s first stage into a reusable one is 100 kg, with the parafoil accounting for 74 kg, the ballute 9 kg, and the remaining mass attributed to modifications such as the parachute attachment and release mechanism and for the circular parachute 71.5 kg with 22.8 kg for canopy, 35.3 kg for suspension lines and 13.4 kg actuators. The parafoil provides superior control, whereas the circular parachute is lighter and more straightforward in design. Consequently, if refurbishment costs are identical for both, the circular parachute emerges as the more advantageous choice.

This study explores the dynamics of parafoil systems under Titan's unique atmospheric conditions using a dual-framework approach. A 6-degree-of-freedom (6DOF) parafoil-capsule model served as a foundation for verification, enabling the development and analysis of a more detailed 9-degree-of-freedom (9DOF) model. The 6DOF model simplifies the system as a single rigid body, while the 9DOF model captures flexible coupling effects between the parafoil and capsule, modeled as two rigid bodies connected by a spring-damper hinge.

Thorough verification techniques, including energy conservation, angular momentum tests, and sensitivity analyses, validated both linear and nonlinear simulations. A novel quasi-linear eigenvalue analysis provided insights into rotational stability, identifying natural frequencies and damping ratios, while exposing the limitations of linearisation in capturing nonlinear dynamic coupling effects. Sensitivity analyses revealed key dependencies on aerodynamic, structural, and mass parameters. Wind studies evaluated stability under steady and gust scenarios, simulating Titan's zonal wind patterns across various angles and altitudes. Results highlight significant differences between 6DOF and 9DOF models, with the parafoil showing moderated oscillations and the capsule exhibiting amplified responses due to dynamic interactions. These findings emphasize the need to model parafoil and capsule dynamics independently for high-fidelity stability analyses.

The study demonstrates the potential of parafoil systems to enhance stability and precision during planetary descent, reducing reliance on propulsion-based corrections. By systematically comparing 6DOF and 9DOF models, the research underscores the importance of flexible coupling dynamics and detailed environmental modelling for designing robust guidance and control systems for planetary exploration.

Nowadays, many people and organizations depend on Global Navigation Satellite Systems (GNSS. Monitoring of GNSS is important to ensure the quality of GNSS measurements and products. The availability of the signals-in-space (SiS) is an essential part of the monitoring of GNSS, but it is not clear how availability is defined and standards for monitoring are lacking. The main research question for this thesis is therefore: Which are the key performance indicators related to availability that unambiguously describe sensor station and system performance in time, how can these be computed in an operational manner, and how can they be presented in a condensed form to the stakeholders? This includes an objective of defining unambiguous performance parameters for sensor station and system, and address the considerations related to the definition. A prototype software tool is created to study the algorithms and compute the key performance indicators.

Availability is in the basis a binary operation: a signal is available or unavailable. When this is applied on daily measurements, daily statistics can be computed. A signal is considered available if the code, carrier phase and C/N0 measurements are present, and meet certain standards. A signal is said to be expected if the satellite is expected to transmit that signal, the receiver is configured to receive that signal, and the signal is not blocked by objects in the signal’s path to the sensor station. For this it’s needed to define and compute an elevation mask for each station.

The sensor station and system performance parameters are computed from a network of sensor stations, using files in the Receiver Independent Exchange format (RINEX). Four key performance indicators are defined for the sensor station performance. The Daily Station Availability describes the part of the day that the station is operational, the Daily Station Total Availability gives how well the station receives, and the Effective Mean Elevation quantifies the elevation mask and thus the location of the sensor station. These three parameters are summarized into the Overall Station Quality parameter, which gives and overall performance class to the sensor station.

For the system performance a satellite is considered available if all signals are received by a sensor station of the monitoring network and the health status is healthy. The satellite is considered unavailable if the signals are received by none of the monitoring stations, while expected by at least two stations, or the health status is unhealthy. The Daily GNSS Availability parameter gives the percentage of the day that the satellite was available and the Daily Available number of Satellites tells how many satellites were available during the day. 

The parameters are computed for a period of 100 days. Results are presented using color codes and by showing only detailed information in case of anomalies or specific investigations. The proposed key performance indicators showed to be very useful at pointing out good performances or anomalies. While SiS availability gives much insight in the performance, a monitoring tool can be improved when combined with other performance aspects.