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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemTrajectory Reconstruction of a Martian Planetary Probe Mission: Reconstruction of the Spirit Mars Exploration Rover Entry Descent Landing Performance(Georgia Institute of Technology, 2008-10) Wells, Grant W. ; Braun, Robert D.Accurate post-flight reconstruction of a vehicle’s trajectory during entry into a planetary atmosphere can produce a wide array of valuable information. Data collected through the reconstruction of entry, descent, and landing system performance enables the quantification of performance margins for future systems. Beyond the engineering knowledge gained through trajectory reconstruction, the results may also be used by planetary scientists to generate an accurate atmospheric profile. This paper provides a reconstruction of the trajectory, vehicle orientation, and atmospheric density profile for the hypersonic and supersonic phases of the Spirit Mars Exploration Rover spacecraft.
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ItemSurvivability and Resiliency of Spacecraft and Space-Based Networks: a Framework for Characterization and Analysis, Version 2(Georgia Institute of Technology, 2008-09-09) Castet, Jean-Francois ; Saleh, Joseph H.Considerations of survivability and resiliency have always been of importance in the design and analysis of military systems. Over the past two decades, the importance of survivability and resiliency has expanded beyond military systems to include public networks and infrastructure systems. The analysis and assessment of networked systems with respect to survivability has become particularly acute in recent years, as attested to by a growing technical literature on the subject. In this paper, we bring these considerations of survivability and resiliency to bear on spacecraft and space-based networks. We develop a framework for comparing the survivability and resiliency of different space architectures, namely that of a monolithic design and a distributed (or networked) space system architecture. There are multiple metrics along which different space architectures can be benchmarked and compared. We argue that if survivability and resiliency are not accounted for, then the evaluation process is likely to be biased in favor of monolithic spacecraft. We show that if in a given context survivability and resiliency are an important requirement for a particular customer, then a distributed architecture is more likely to satisfy this requirement than a monolithic spacecraft design. We discuss in the context of our framework different classes of threats, as well as the high-frequency and low-frequency system response to (or coping strategies with) these shocks or damaging events. We illustrate the importance of this characterization for a formal definition of survivability and resiliency and a proper quantitative analysis of the subject. Finally, we propose in future work to integrate our framework with a design tool that allows the exploration of the design trade-space of distributed space architecture and show how survivability can be “optimized” or traded against other system attributes.
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ItemSurvivability and Resiliency of Spacecraft and Space-Based Networks: a Framework for Characterization and Analysis, Version 1(Georgia Institute of Technology, 2008-09) Castet, Jean-Francois ; Saleh, Joseph H.Considerations of survivability and resiliency have always been of importance in the design and analysis of military systems. Over the past two decades, the importance of survivability and resiliency has expanded beyond military systems to include public networks and infrastructure systems. The analysis and assessment of networked systems with respect to survivability has become particularly acute in recent years, as attested to by a growing technical literature on the subject. In this paper, we bring these considerations of survivability and resiliency to bear on spacecraft and space-based networks. We develop a framework for comparing the survivability and resiliency of different space architectures, namely that of a monolithic design and a distributed (or networked) space system architecture. There are multiple metrics along which different space architectures can be benchmarked and compared. We argue that if survivability and resiliency are not accounted for, then the evaluation process is likely to be biased in favor of monolithic spacecraft. We show that if in a given context survivability and resiliency are an important requirement for a particular customer, then a distributed architecture is more likely to satisfy this requirement than a monolithic spacecraft design. We discuss in the context of our framework different classes of threats, as well as the high-frequency and low-frequency system response to (or coping strategies with) these shocks or damaging events. We illustrate the importance of this characterization for a formal definition of survivability and resiliency and a proper quantitative analysis of the subject. Finally, we propose in future work to integrate our framework with a design tool that allows the exploration of the design trade-space of distributed space architecture and show how survivability can be “optimized” or traded against other system attributes.
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ItemMultiobjective Hypersonic Entry Aeroshell Shape Optimization(Georgia Institute of Technology, 2008-09) Theisinger, John E. ; Braun, Robert D.A capability has been developed that utilizes multiobjective optimization to identify hypersonic entry aeroshell shapes that will increase landed mass capability. Aeroshell shapes are parameterized using non-uniform rational B-splines to generate complete aeroshell surfaces. Hypersonic aerodynamic objectives and constraints are computed by numerically integrating pressure coefficient distributions obtained using Newtonian flow theory. An integrated optimization environment is created using iSIGHT with single- and multiobjective evolutionary algorithms. Results are presented based on optimization using constraints derived from the aeroshell for the Mars Science Laboratory mission. Resulting solutions clearly demonstrate the trade-offs between drag-area, static stability, and volumetric efficiency for this particular mission.
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ItemSurvivability and Resiliency of Spacecraft and Space-Based Networks: a Framework for Characterization and Analysis(Georgia Institute of Technology, 2008-09) Castet, Jean-Francois ; Saleh, Joseph H.Considerations of survivability and resiliency have always been of importance in the design and analysis of military systems. Over the past two decades, the importance of survivability and resiliency has expanded beyond military systems to include public networks and infrastructure systems. The analysis and assessment of networked systems with respect to survivability has become particularly acute in recent years, as attested to by a growing technical literature on the subject. In this paper, we bring these considerations of survivability and resiliency to bear on spacecraft and space-based networks. We develop a framework for comparing the survivability and resiliency of different space architectures, namely that of a monolithic design and a distributed (or networked) space system architecture. There are multiple metrics along which different space architectures can be benchmarked and compared. We argue that if survivability and resiliency are not accounted for, then the evaluation process is likely to be biased in favor of monolithic spacecraft. We show that if in a given context survivability and resiliency are an important requirement for a particular customer, then a distributed architecture is more likely to satisfy this requirement than a monolithic spacecraft design. We discuss in the context of our framework different classes of threats, as well as the high-frequency and low-frequency system response to (or coping strategies with) these shocks or damaging events. We illustrate the importance of this characterization for a formal definition of survivability and resiliency and a proper quantitative analysis of the subject. Finally, we propose in future work to integrate our framework with a design tool that allows the exploration of the design trade-space of distributed space architecture and show how survivability can be "optimized" or traded against other system attributes.
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ItemA Series of Unforeseen Events: The Space Shuttle Mission Evolution Flexibility(Georgia Institute of Technology, 2008-09) Lafleur, Jarret M. ; Saleh, Joseph H.A common objective in the design of a new space system is that of flexibility, or the capability to easily modify that system in the future in response to a changing environment or changing requirements. The focus of this paper is a case study of the U.S. Space Shuttle to glean some insight into fundamental characteristics of flexibility in human space systems and how this may be applied to future systems. Data is presented on the evolution of mission requirements over time for 120 missions performed by the Space Shuttle over a period of approximately 27 years. Distinct trends in the time domain - as well causes of these trends - are identified, and early manifest plans from 1982 serve as a confirmation that these trends were not originally anticipated. Eight examples are then presented of engineering modifications that allowed the Shuttle to adapt and accommodate these requirement changes. Conclusions are drawn on the nature of flexibility as experienced by the Space Shuttle. Finally, remaining questions are posed regarding how flexibility is considered in the initial stages of design for space systems.
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ItemSurvey of Flexibility in Space Exploration Systems(Georgia Institute of Technology, 2008-09) Lafleur, Jarret M. ; Saleh, Joseph H.An increasingly common objective in the design of new space systems is the property of flexibility, or the capability to easily modify a system after it has been fielded in response to a changing environment or changing requirements. The body of research on this topic has been growing, but substantial work remains in developing metrics for characterizing system flexibility and trading it against other metrics of interest. This paper samples from the history of space exploration to glean heuristic insight into characteristics of flexibility in space exploration systems and their potential application to future systems. Divided into categories of intra- and inter-mission modification, examples include the Hubble Space Telescope, Mir space station, International Space Station, Apollo, Space Shuttle, and robotic Venera program. In several cases, metrics are identified which show clear performance gains due to changes after a system is fielded, and in all cases, environment or requirement changes that prompted system change are identified. Also discussed are examples where flexibility proved critical to mission success. Modular design and separation of functionality are recognized as likely flexibility-enabling characteristics. Also, briefly discussed are examples of non-configurational (e.g. software and trajectory) flexibility in space exploration applications.
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ItemDesign Space Pruning Heuristics and Global Optimization Method for Conceptual Design of Low-Thrust Asteroid Tour Missions(Georgia Institute of Technology, 2008-09) Alemany, Kristina ; Braun, Robert D.Electric propulsion has recently become a viable technology for spacecraft, enabling shorter flight times, fewer required planetary gravity assists, larger payload masses, and/or smaller launch vehicles. With the maturation of this technology, however, comes a new set of challenges in the area of trajectory design. In 2006, the 2nd Global Trajectory Optimization Competition (GTOC2) posed a difficult mission design problem: to design the best possible low-thrust trajectory, in terms of final mass and total mission time, that would rendezvous with one asteroid in each of four pre-defined groups. Even with recent advances in low-thrust trajectory optimization, a full enumeration of this problem was not possible. This work presents a two-step methodology for determining the optimum solution to a low-thrust, combinatorial asteroid rendezvous problem. First is a pruning step that uses a heuristic sequence to quickly reduce the size of the design space. Second, a multi-level genetic algorithm is combined with a low-thrust trajectory optimization method to locate the best solutions of the reduced design space. The proposed methodology is then validated by applying it to a problem with a known solution.
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ItemA Concept for the Entry, Descent, and Landing of High-Mass Payloads at Mars(Georgia Institute of Technology, 2008-09) Korzun, Ashley M. ; Stahl, Benjamin A. ; Dubos, Gregory F. ; Quicksall, John J. ; Iwata, Curtis K.The architecture concepts and aggressive science objectives for the next phases of Mars exploration will require landed masses an order of magnitude or greater than any Mars mission previously planned or flown. Additional studies have shown the requirements for missions more ambitious than the 2009 Mars Science Laboratory (~ 900 kg payload mass) to extend beyond the capabilities of Viking-heritage entry, descent, and landing (EDL) technologies, namely blunt-body aeroshells, supersonic disk-gap-band parachutes, and existing TPS materials. This study details a concept for Mars entry, descent, and landing capable of delivering a 20 t payload within 1 km of a target landing site at 0 km MOLA. The concept presented here explores potentially enabling EDL technologies for the continued robotic and eventual human exploration of Mars, moving beyond the Viking-heritage systems relied upon for the past 30 years of Mars exploration. These technologies address the challenges of hypersonic guidance, supersonic deceleration, precision landing, and surface hazard avoidance. Without support for the development of these enabling technologies in the near term, the timeline for the successful advanced exploration of Mars will likely extend indefinitely.
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ItemLunar Module Descent Mission Design(Georgia Institute of Technology, 2008-08) Wilhite, Alan W. ; Tolson, Robert ; Moen, Marina M.Various lunar descent trajectories were analyzed that include the optimization of the Apollo constrained mission trajectory, a fully optimized minimum energy trajectory, and a optimal, constrained trajectory using current instrumentation technology. Trade studies were conducted to determine the impacts of mission assumptions, pilot in the loop/automated flight demands, and additional constraints for the present recurring missions to the same outpost landing site. For mission design at this conceptual phase of the program, the Apollo pre-mission planning was applied to account for known contingencies (hardware, instrumentation known uncertainties) and unknown unknowns. The mission Delta-V's are presented in a risk form of conservative, nominal, and optimistic range where 90 percent of Delta-V is derived by trajectory analysis and the other 10 percent was derived from a qualitative analysis from Apollo 11 pre-mission planning. The recommendations for the Delta Vs are the following: conservative (Apollo derived) (2262 m/s), nominal (2053 m/s), and optimistic (1799 m/s). Because of the qualitative nature of the results, the degree of autonomy assumed, additional safety considerations for a lunar outpost, and the impact of advanced instrumentation, more in-depth analyses are required to refine the present recommendations.