The 2012 Decadal Survey has stated that there is a critical role for a Venus In-situ Explore (VISE) missions to a variety of important sites, specifically the Tessera terrain. This work aims to answer the Decadal Survey's call by developing a new comprehensive Entry, Descent, Landing, and Locomotion (EDLL) vehicle for in-situ exploration of Venus, especially in the Tessera regions. TANDEM, the Tension Adjustable Network for Deploying Entry Membrane, is a new planetary probe concept in which all of EDLL is achieved by a single multifunctional tensegrity structure. The concept uses same fundamental concept as the ADEPT (Adaptable Deployable Entry and Placement Technology) deployable heat shield but replaces the standard internal structure with the structure from the tensegrity-actuated rover to provide a combined aeroshell and rover design. The tensegrity system implemented by TANDEM reduces the mass of the overall system while enabling surface locomotion and mitigating risk associated with landing in the rough terrain of Venus's Tessera regions, which is otherwise nearly inaccessible to surface missions. TANDEM was compared to other state-of-the-art lander designs for an in-situ mission to Venus. It was shown that TANDEM provides the same scientific experimentation capabilities that were proposed for the VITaL mission, with a combined mass reduction for the aeroshell and lander of 52% (1445 kg), while eliminating the identified risks associated with entry loads and very rough terrain. Additionally, TANDEM provides locomotion when on the surface as well as a host of other maneuvers during entry and descent, which was not present in the VITaL design. Based on its unique multifunctional infrastructure and excellent crashworthiness for impact on rough surfaces, TANDEM presents a robust system to address some of the Decadal Survey's most pressing questions about Venus. / Ph. D. / NASA has proposed the possibility of performing a robotic mission to Venus in this upcoming decade. This could be NASA’s first attempt to design a robot that is capable of landing on the surface of our solar systems hottest planet. Venus presents a great exploration opportunity, as it is our closest planetary neighbor. Venus is similar to Earth in both size and location in the solar system, yet it is profoundly different in many other aspects regarding habitability. There is a significant scientific interest in exploring the mysteries of the greenhouse gases and runaway climate change present in the Venusian atmosphere. Understanding Venus’ atmosphere will help us to increase our knowledge of Earth’s atmosphere. Exploring the difference in these two planets will greatly further our intuition of other planetary systems and will aid in our search for life in the universe. Yet, exploring Venus presents a number of severe engineering challenges: the extreme temperature and pressure at the planet's surface, the highly corrosive atmosphere, and lack of terrain resolution caused by the dense permanent cloud layer. In order to address these engineering challenges, a new ultra-lightweight planetary probe has been invented. TANDEM, the Tension Adjustable Network for Deploying Entry Membrane, is unique in its design as it has combined all of the subsystems in needs to safely land on the surface into a single lightweight, multifunctional structure. This enables the design to be nearly 1.5 metric tons lighter than the same mission that was proposed in 2010 using the current state-of-the-art technologies. Based on this and other unique capabilities that are provided, TANDEM presents a robust system to address some of NASA’s most pressing questions about Venus.

To enable a crewed mission to Mars, precision landing capabilities of Entry, Descent, and Landing (EDL) systems must be improved. The need for larger payloads, higher landing sites, and controllability has motivated the National Aeronautics and Space Administration (NASA) to invest in new technologies to replace traditional rigid aeroshell systems, which are limited in size by the payload envelope of existing launch vehicles. A Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is an emerging technology that provides an increased drag area by inflating the aeroshell to diameters not possible with rigid aeroshells, allowing the vehicle to decelerate higher in the atmosphere, offering access to higher landing sites with more timeline margin. To enable a crewed mission to Mars, future entry vehicles will require precision landing capabilities that go beyond heritage EDL guidance strategies that utilize fuel-intensive and error-prone bank reversals. A novel Direct Force Control (DFC) approach of independently controlling the lift and side force of a vehicle that utilizes a HIAD with an aerodynamic shape morphing capability is proposed. To date, the mechanisms and controls required to morph an inflatable structure to generate lift have not been explored. In this dissertation, novel morphing HIAD concepts are investigated and designed to satisfy mission requirements, aerodynamic tools are built to assess the aerodynamic performance of morphed blunt body shapes, and a structural feasibility study is performed using models correlated to test data to determine the forces required to generate the desired shape change based on a crewed mission to Mars. A novel control methodology is introduced by applying a unique DFC strategy to a morphing HIAD to enhance precision landing capabilities of EDL systems, and the ability of a morphing HIAD to safely land a vehicle on Mars is assessed by performing a closed-loop feedback simulation for a Mars entry trajectory. Finally, a control mechanism is demonstrated on a small-scale inflatable structure. Conclusions and contributions of this research are presented along with a discussion of future research opportunities of morphing HIADs. / PHD / A Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is a reentry vehicle designed to inflate the aeroshell to diameters outside of the payload shroud to decelerate the vehicle higher in the atmosphere, offering access to higher landing sites with more timeline margin. To enable a crewed mission to Mars, the landing accuracy of a HIAD must be significantly improved beyond heritage bank angle control approaches that are fuel-intensive and prone to errors. A novel Direct Force Control (DFC) approach is proposed that permits direct control of the angle of attack and sideslip by morphing the inflatable shape of the HIAD to enable its precision landing capabilities. A morphing HIAD concept is proposed in this dissertation to satisfy the requirements of landing humans successfully on Mars. Aerodynamic tools are built to assess the aerodynamic performance of morphed blunt body shapes, and structural models correlated with test data are created to determine the forces required to generate the desired shape change. Novel DFC methodologies are introduced and applied to a morphing HIAD system, a motor sizing study is performed to compare the total energy usage and cost and weight estimates of the morphing HIAD to heritage control systems, and a Mars entry trajectory simulation is performed to assess the capability of a morphing HIAD to safely land a crewed vehicle on Mars. Finally, a control mechanism is demonstrated on a small-scale inflatable structure. Conclusions and contributions of this research are presented along with a discussion of future research opportunities of morphing HIADs.

The reconstruction of entry, descent and landing (EDL) trajectories is significantly affected by the knowledge of the atmospheric conditions during flight. Away from Earth, this knowledge is generally characterized by a high degree of uncertainty, which drives the accuracy of many important atmosphere-relative states. One method of obtaining the in-flight atmospheric properties during EDL is to utilize the known vehicle aerodynamics in deriving the trajectory parameters. This is the approach taken by this research in developing a methodology for accurate estimation of ambient atmospheric conditions and atmosphere-relative states. The method, referred to as the aerodynamic database (ADB) reconstruction, performs reconstruction by leveraging data from flight measurements and pre-flight models. In addition to the estimation algorithm, an uncertainty assessment for the ADB reconstruction method is developed. This uncertainty assessment is a unique application of a fundamental analysis technique that applies linear covariance mapping to transform input variances into output uncertainties. The ADB reconstruction is applied to a previous mission in order to demonstrate its capability and accuracy. Flight data from the Mars Science Laboratory (MSL) EDL, having successfully completed on August 5th 2012, is used for this purpose. Comparisons of the estimated states are made against alternate reconstruction approaches to understand the advantages and limitations of the ADB reconstruction. This thesis presents a method of reconstruction for EDL systems that can be used as a valuable tool for planetary entry analysis.

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There is significant uncertainty in our knowledge of the Martian atmosphere and the aerodynamics of the Mars entry, descent, and landing (EDL) systems. These uncertainties result in conservatism in the design of the EDL vehicles leading to higher system masses and a broad range of performance predictions. Data from flight instrumentation onboard Mars EDL systems can be used to quantify these uncertainties, but the existing dataset is sparse and many parameters of interest have not been previously observable. Many past EDL reconstructions neither utilize statistical information about the uncertainty of the measured data nor quantify the uncertainty of the estimated parameters. Statistical estimation methods can blend together disparate data types to improve the reconstruction of parameters of interest for the vehicle. For example, integrating data obtained from aeroshell-mounted pressure transducers, inertial measurement unit, and radar altimeter can improve the estimates of the trajectory, atmospheric profile, and aerodynamic coefficients, while also quantifying the uncertainty in these estimates. These same statistical methods can be leveraged to improve current engineering models in order to reduce conservatism in future EDL vehicle design. The work in this thesis presents a comprehensive methodology for parameter reconstruction and uncertainty quantification while blending dissimilar Mars EDL datasets. Statistical estimation methods applied include the Extended Kalman Filter, Unscented Kalman Filter, and Adaptive Filter. The estimators are applied in a manner in which the observability of the parameters of interest is maximized while using the sparse, disparate EDL dataset. The methodology is validated with simulated data and then applied to estimate the EDL performance of the 2012 Mars Science Laboratory. The reconstruction methodology is also utilized as a tool for improving vehicle design and reducing design conservatism. A novel method of optimizing the design of future EDL atmospheric data systems is presented by leveraging the reconstruction methodology. The methodology identifies important design trends and the point of diminishing returns of atmospheric data sensors that are critical in improving the reconstruction performance for future EDL vehicles. The impact of the estimation methodology on aerodynamic and atmospheric engineering models is also studied and suggestions are made for future EDL instrumentation.

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