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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemHigh Mass Mars Entry, Descent, and Landing Architecture Assessment(Georgia Institute of Technology, 2009-09) Steinfeldt, Bradley A. ; Theisinger, John E. ; Korzun, Ashley M. ; Clark, Ian G. ; Grant, Michael J. ; Braun, Robert D.As the nation sets its sight on returning humans to the Moon and going onward to Mars, landing high mass payloads (>/= 2 t) on the Mars surface becomes a critical technological need. Viking heritage technologies (e.g., 70degrees sphere-cone aeroshell, SLA-561V thermal protection system, and supersonic disk-gap-band parachutes) that have been the mainstay of the United States' robotic Mars exploration program do not provide sufficient capability to land such large payload masses. In this investigation, a parametric study of the Mars entry, descent, and landing design space has been conducted. Entry velocity, entry vehicle configuration, entry vehicle mass, and the approach to supersonic deceleration were varied. Particular focus is given to the entry vehicle shape and the supersonic deceleration technology trades. Slender bodied vehicles with a lift-to-drag ratio (L=D) of 0.68 are examined alongside blunt bodies with L=D = 0.30. Results demonstrated that while the increased L=D of a slender entry configuration allows for more favorable terminal descent staging conditions, the greater structural efficiencies of blunt body systems along with the reduced acreage required for the thermal protection system affords an inherently lighter vehicle. The supersonic deceleration technology trade focuses on inflatable aerodynamic decelerators (IAD) and supersonic retropropulsion, as supersonic parachute systems are shown to be excessively large for further consideration. While entry masses (the total mass at the top of the Mars atmosphere) between 20 and 100 t are considered, a maximum payload capability of 37.3 t results. Of particular note, as entry mass increases, the gain in payload mass diminishes. It is shown that blunt body vehicles provide sufficient vertical L=D to decelerate all entry masses considered through the Mars atmosphere with adequate staging conditions for the propulsive terminal descent. A payload mass fraction penalty of approximately 0.3 exists for the use of slender bodied vehicles. Another observation of this investigation is that the increased aerothermal and aerodynamic loads induced from a direct entry trajectory (velocity ~6.75 km/s) reduce the payload mass fraction by approximately 15% compared to entry from orbital velocity (~4 km/s). It should be noted that while both IADs and supersonic retropropulsion were evaluated for each of the entry masses, configurations, and velocities, the IAD proved to be more mass-efficient in all instances. The sensitivity of these results to modeling assumptions was also examined. The payload mass of slender body vehicles was observed to be approximately four times more sensitive to modeling assumptions and uncertainty than blunt bodies.
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ItemPerformance Characterization of Supersonic Retropropulsion for Application to High-Mass Mars Entry, Descent, and Landing(Georgia Institute of Technology, 2009-08) Korzun, Ashley M. ; Braun, Robert D.Prior high-mass Mars EDL systems studies have neglected aerodynamic-propulsive interactions and performance impacts during the supersonic phase of descent. The goal of this investigation is to accurately evaluate the performance of supersonic retropropulsion with increasing vehicle ballistic coefficient across a range of initiation conditions relevant for future high-mass Mars landed systems. Past experimental work has established supersonic retropropulsion trends in static aerodynamics as a function of retropropulsion configuration, freestream conditions, and thrust. From this experimental database, an aerodynamic-propulsive interactions model is created. EDL system performance results are developed with the potential aerodynamic drag preservation included and excluded during this phase of flight for comparison against prior studies. The results of this investigation demonstrate the significance of aerodynamic drag preservation as a function of retropropulsion initiation conditions, characterize mass optimal trajectories utilizing supersonic retropropulsion, and compare propulsion system requirements with existing propulsion systems and systems under development for future exploration missions.
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ItemEntry, Descent, and Landing System Design for the Mars Gravity Biosatellite(Georgia Institute of Technology, 2008-06-26) Korzun, Ashley M. ; Smith, Brandon P. ; Yu, Chi-Yau ; Hartzell, Christine M. ; Hott, Kyle B. ; Place, Laura A. ; Braun, Robert D. ; Martinelli, Scott K.Mars Gravity Biosatellite is a novel program aimed at providing data on the effects of partial gravity on mammalian physiology. A collaboration between MIT and Georgia Tech, this student-developed free-flyer spacecraft is designed to carry a payload of 15 mice into low Earth orbit, rotating to generate accelerations equivalent to Martian gravity. After 35 days, the payload will re-enter the atmosphere and be recovered for study. Having engaged more than 500 students to date in space life science, systems engineering, and hardware development, the Mars Gravity Biosatellite program offers a unique, interdisciplinary educational opportunity to address a critical challenge in the next steps in human space exploration through the development of a free-flyer platform for partial gravity science with full entry, descent, and landing (EDL) capability. Execution of a full entry, descent, and landing from low Earth orbit is a rare requirement among university-class spacecraft. The EDL design for the Mars Gravity Biosatellite is driven by requirements on the allowable deceleration profile for a payload of de-conditioned mice and maximum allowable recovery time. The 260 kg entry vehicle follows a ballistic trajectory from low Earth orbit to a target recovery site at the Utah Test and Training Range. Reflecting an emphasis on design simplicity and the use of heritage technology, the entry vehicle uses the Discoverer aeroshell geometry and leverages aerodynamic decelerators for mid-air recovery and operations originally developed for the Genesis mission. This paper presents the student-developed EDL design for the Mars Gravity Biosatellite, with emphasis on trajectory design, dispersion analysis, and mechanical design and performance analysis of the thermal protection and parachute systems. Also included is discussion on EDL event sequencing and triggers, contingency operations, the deorbit of the spacecraft bus, plans for further work, and the educational impact of the Mars Gravity Biosatellite program.
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ItemEntry, Descent, and Landing System Design for the Mars Gravity Biosatellite(Georgia Institute of Technology, 2008-06) Korzun, Ashley M. ; Smith, Brandon P. ; Hartzell, Christine M. ; Yu, Chi-Yau ; Place, Laura A. ; Martinelli, Scott K. ; Braun, Robert D. ; Hott, Kyle B.Execution of a full entry, descent, and landing (EDL) from low Earth orbit is a rare requirement among university class spacecraft. Successful completion of the Mars Gravity Biosatellite mission requires the recovery of a mammalian payload for post-flight analysis of the effects of partial gravity. The EDL design for the Mars Gravity Biosatellite is driven by requirements on the allowable deceleration profile for a payload of deconditioned mice and maximum allowable recovery time. The 260 kg entry vehicle follows a ballistic trajectory from low Earth orbit to a target recovery site at the Utah Test and Training Range. Reflecting an emphasis on design simplicity and the use of heritage technology, the entry vehicle uses the Discoverer aeroshell geometry and leverages aerodynamic decelerators for mid-air recovery and operations originally developed for the Genesis mission. This paper presents the student-developed EDL design for the Mars Gravity Biosatellite, with emphasis on trajectory design, dispersion analysis, and mechanical design and performance analysis of the thermal protection and parachute systems. Also included is discussion on EDL event sequencing and triggers, the de-orbit of the spacecraft bus, plans for further work, and the educational impact of the Mars Gravity Biosatellite program.
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ItemA Survey of Supersonic Retropropulsion Technology for Mars Entry, Descent, and Landing(Georgia Institute of Technology, 2008-03) Korzun, Ashley M. ; Cruz, Juan R. ; Braun, Robert D.This paper presents a literature survey on supersonic retropropulsion technology as it applies to Mars entry, descent, and landing (EDL). The relevance of this technology to the feasibility of Mars EDL is shown to increase with ballistic coefficient to the point that it is likely required for human Mars exploration. The use of retropropulsion to decelerate an entry vehicle from hypersonic or supersonic conditions to a subsonic velocity is the primary focus of this review. Discussed are systems level studies, general flowfield characteristics, static aerodynamics, vehicle and flowfield stability considerations, and aerothermodynamics. The experimental and computational approaches used to develop retropropulsion technology are also reviewed. Finally, the applicability and limitations of the existing literature and current state-of-the-art computational tools to future missions are discussed in the context of human and robotic Mars exploration.1,2
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ItemMars Gravity Biosatellite: Engineering, Science, and Education(Georgia Institute of Technology, 2007-09) Korzun, Ashley M. ; Braun, Robert D. ; Wagner, Erika B. ; Fulford-Jones, Thaddeus R.F. ; Deems, Elizabeth C. ; Judnick, Daniel C. ; Keesee, John E.The Mars Gravity Biosatellite is a novel program aimed at providing data on the effects of partial gravity on mammalian physiology. Physiological problems intrinsic to prolonged stays in microgravity have long been concerns of manned spaceflight and will continue to be a significant obstacle in achieving the goals outlined in NASA’s Vision for Space Exploration. This student-developed, free-flyer spacecraft is designed to carry a payload of 15 mice into low Earth orbit, rotating to generate an acceleration environment equivalent to Martian gravity. After 35 days, the payload will be de-orbited and recovered for study. Data collected during the mission and post-recovery will be used to characterize the physiological changes incurred under partial gravity conditions and validate the models used in designing the spacecraft. This paper presents the preliminary design of the spacecraft. By providing groundbreaking flight data on the effects of partial gravity on mammalian physiology and engaging over 500 students to date, the Mars Gravity Biosatellite program is working to enable successful human exploration of the Moon and Mars while training and inspiring a new generation of scientists and engineers.