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    Planning for Childcare
    (Georgia Institute of Technology, 2024-04-20) Tamura, Micah
    City planners play a pivotal role in establishing the resources communities need to accomplish their goals. Childcare is a critical resource that supports parents' ability to work, promotes children’s development, and advances economic growth. I performed a spatial analysis to identify census tracts that need more childcare accessibility. The analysis compared measures of childcare availability, populations of women likely to use childcare, and economic distress to assess the need for childcare in census tracts within the Atlanta–Sandy Springs–Roswell, GA Metropolitan Statistical Area (Atlanta Metro). I then created a report with spatial analysis, childcare leader insight, and city planning policy solutions that could be incorporated into a comprehensive plan. The purpose of the analysis and the report is to provide a framework for city planners to improve childcare accessibility.
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    BioDOME: Concept of an EDL System for Returning Small Biological Samples from LEO
    (Georgia Institute of Technology, 2015-06) Rossman, Grant ; LeVine, Matthew ; Lawlor, Sean ; Sloss, Tyler ; Mishra, Pranay ; Tan, Zu Puayen ; Braun, Robert D.
    A conceptual design of an Earth return vehicle is presented with the goal of safely returning biological samples from orbit. Key entry, descent, and landing trade studies were completed at the conceptual level for two different mission scenarios: return from the International Space Station (ISS) and an autonomous, free-flying vehicle returning from Low Earth Orbit (LEO). The analyses that follow for each key subsystem drove design decisions to create the Biopan Deployment in Orbit for Microgravity Exposure (BioDOME) vehicle with the versatility to satisfy both of the aforementioned mission scenarios. The final design features a ballistic entry, a 45 ◦ spherecone aeroshell with a diameter of 88-cm, a PICA heatshield with a thickness of 7.7 cm, and a passive landing system containing an 8-m diameter ringsail parachute combined with a 7.8-cm thick crushable carbon foam. Analysis of the vehicle performance verified survivability of biological samples due to heat and deceleration loads from entry. Trajectory dispersion analysis yielded crossrange and downrange limited to ±1.5-km and ±30-km, respectively, while landing velocity was confirmed to be ≤ 4.0-m/s for all cases.
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    Conceptual Modeling of Supersonic Retropropulsion Flow Interactions and the Relationship to System Performance
    (Georgia Institute of Technology, 2012-06) Korzun, Ashley M. ; Braun, Robert D.
    Supersonic retropropulsion is an entry, descent, and landing technology applicable to and potentially enabling the high-mass missions to the surface required for advanced robotic and human exploration at Mars. For conceptual design, an initial understanding of the significance of retropropulsion configuration on the vehicle’s static aerodynamic characteristics and the relation of this configuration to other vehicle performance metrics that traditionally determine vehicle configuration is necessary. This work develops an approximate model for the aerodynamic - propulsive flow interaction based on momentum transfer within the flowfield and the geometry of relevant flow structures. This model is used to explore the impact of operating conditions, required propulsion system performance, propulsion system composition, and vehicle configuration on the integrated aerodynamic drag characteristics of full-scale vehicles for Mars entry, descent, and landing. Conclusions are then drawn on the fidelity and effort required to support specific design trades for supersonic retropropulsion.
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    Integrated Trajectory, Atmosphere, and Aerothermal Reconstruction Methodology Using the MEDLI Dataset
    (Georgia Institute of Technology, 2012-06) Dutta, Soumyo ; Mahzari, Milad ; White, Todd R. ; Braun, Robert D.
    The Mars Science Laboratory (MSL) mission’s instrumentation will enable accurate reconstruction of the vehicle’s entry, descent, and landing (EDL) performance including the trajectory, the observed atmosphere, aerodynamics, aeroheating, and heatshield material response. The objective of this paper is to develop methodologies for an integrated approach to the reconstruction of the vehicle’s EDL performance. Two estimation approaches are presented: Serial and Concurrent. The serial approach is demonstrated by application to the Mars Pathfinder flight data and estimating trajectory and aeroheating performance.
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    Mass Model Development for Conceptual Design of a Hypersonic Rigid Deployable Decelerator
    (Georgia Institute of Technology, 2012-06) Cruz-Ayoroa, Juan G. ; Kazemba, Cole D. ; Steinfeldt, Bradley A. ; Kelly, Jenny R. ; Clark, Ian G. ; Braun, Robert D.
    As the required payload masses for planetary entry systems increase, innovative entry vehicle decelerator systems are becoming a topic of interest. With this interest comes a growing need for the capability to characterize the performance of such decelerators. This work proposes a first-order mass model for fully-rigid deployable decelerator systems. The analytical methodology that is presented can be applied to a wide range of entry conditions and material properties for rapid design space exploration. The tool is applied to a case study of a C/SiC hot structure decelerator at Mars for comparison to the performance of the Hypersonic Inflatable Aerodynamic Decelerator concepts presented in a recent EDL-SA study. Results show that the performance of a rigid deployable structure can be comparable to that of a Hypersonic Inflatable Aerodynamic Decelerator at high entry ballistic coefficients and small decelerator diameters.
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    Supersonic Retropropulsion Flight Test Concepts
    (Georgia Institute of Technology, 2011-06) Post, Ethan A. ; Dupzyk, Ian C. ; Korzun, Ashley M. ; Dyakonov, Artem A. ; Tanimoto, Rebekah L. ; Edquist, Karl T.
    NASA’s Exploration Technology Development and Demonstration Program has proposed plans for a series of three sub-scale flight tests at Earth for supersonic retropropulsion, a candidate decelerator technology for future, high-mass Mars missions. The first flight test in this series is intended to be a proof-of-concept test, demonstrating successful initiation and operation of supersonic retropropulsion at conditions that replicate the relevant physics of the aerodynamic-propulsive interactions expected in flight. Five sub-scale flight test article concepts, each designed for launch on sounding rockets, have been developed in consideration of this proof-of-concept flight test. Commercial, off-the-shelf components are utilized as much as possible in each concept. The design merits of the concepts are compared along with their predicted performance for a baseline trajectory. The results of a packaging study and performance-based trade studies indicate that a sounding rocket is a viable launch platform for this proof-of-concept test of supersonic retropropulsion.
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    Performance Characterization, Sensitivity and Comparison of a Dual Layer Thermal Protection System
    (Georgia Institute of Technology, 2011-06) Kazemba, Cole D. ; McGuire, Mary Kathleen ; Howard, Austin ; Clark, Ian G. ; Braun, Robert D.
    With the goal of landing high-mass cargo or crewed missions on Mars, NASA has been developing new thermal protection technologies with enhanced capability and reduced mass compared to traditional approaches. Two examples of new thermal protection system (TPS) concepts are dual layer and flexible TPS. Each of these systems introduces unique challenges along with potential performance enhancements. Traditional monolithic ablative TPS, which have been flown on every Mars robotic mission to date, use a single layer of ablative material. The new dual layer TPS concepts utilize an insulating layer of material beneath an ablative layer to increase efficiency and save mass. A study was conducted on the dual layer system to identify sensitivities in performance to uncertainties in material properties and aerothermal environments. A performance metric which is independent of the system construction was developed in order to directly compare the abilities and benefits between the traditional, dual layer and eventually, flexible systems. Using a custom MATLAB code enveloping the Fully Implicit Ablation and Thermal Response Program (FIAT), the required TPS areal mass was calculated for several different parametric scenarios. Overall TPS areal mass was found to be most sensitive to the constraining allowable temperature in each system and aerothermal heat transfer augmentation (attributed here to material surface roughness). From these preliminary results it was found that the nominal dual layer TPS construction investigated could produce improvements over a traditional TPS in the specified performance metric between 14-36%, depending on the flight environments and total integrated heat load expected.
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    Statistical Entry, Descent and Landing Performance Reconstruction of the Mars Phoenix Lander
    (Georgia Institute of Technology, 2011-06) Dutta, Soumyo ; Clark, Ian G. ; Russell, Ryan P. ; Braun, Robert D.
    The Phoenix Lander successfully landed on the surface of Mars on May 25, 2008. During the entry, descent and landing (EDL), the vehicle had instruments on-board that took sensed acceleration, angular rates and altimeter measurements. In this study, methodology used to reconstruct the trajectory and other EDL performance information using a statistical filter to process the observations from the sensors is demonstrated. A statistical filter estimates parameters simultaneously with the uncertainty in the estimates. The results presented here will include Phoenix’s event timeline, trajectory information, time-of-flight atmosphere and aerodynamic coefficients of an EDL subsystem as well as the uncertainty in the estimated states.
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    Phoenix Location Determination using HiRISE Imagery
    (Georgia Institute of Technology, 2010-06) Wells, Grant ; Dutta, Soumyo ; Mattson, Sarah ; Lisano, Michael
    This investigation looked into determining Phoenix’s position using an image taken by the University of Arizona’s High Resolution Imaging Science Experiment camera. The objective was to test how accurately a position for the lander could be determined during entry, descent, and landing to provide an alternate means of position determination independent of Phoenix navigation data or Phoenix telemetry in the event of the spacecraft’s on-board inertial measurement unit failing or a communications breakdown that prevented the return of the data.
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    Subsonic and Transonic Wind Tunnel Testing of Two Inflatable Aerodynamic Decelerators
    (Georgia Institute of Technology, 2010-06) Tanner, Christopher L. ; Cruz, Juan R. ; Hughes, Monica F. ; Clark, Ian G. ; Braun, Robert D.
    Two inflatable aerodynamic decelerator designs were tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center: a tension cone and an isotensoid. The tension cone consists of a flexible tension shell attached to a torus and the isotensoid employs a ram-air inflated envelope. Tests were conducted at Mach numbers from 0.3 to 1.08 and Reynolds numbers from 0.59 to 2.46 million. The main objective of these tests was to obtain static aerodynamic coefficients at subsonic and transonic speeds to supplement supersonic aerodynamic data for these same two designs. The axial force coefficients of both designs increased smoothly from subsonic through transonic Mach numbers. Dynamic data show significant oscillation of the tension cone and minimal oscillation of the isotensoid. The transonic and subsonic data will be used to assemble an inflatable decelerator aerodynamic database for use in computational analyses and system studies.