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Space Systems Design Laboratory (SSDL)
Space Systems Design Laboratory (SSDL)
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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 Systematic Concept Exploration Methodology Applied to Venus In Situ Explorer(Georgia Institute of Technology, 2008-06) Lafleur, Jarret M. ; Lantoine, Gregory ; Hensley, Andrew L. ; Retaureau, Ghislain J. ; Kranzusch, Kara M. ; Hickman, Joseph W. ; Wilson, Marc N. ; Schrage, Daniel P.One of the most critical tasks in the design of a complex system is the initial conversion of mission or program objectives into a baseline system architecture. Presented in this paper is a methodology to aid in this process that is frequently used for aerospace problems at the Georgia Institute of Technology. In this paper, the methodology is applied to initial concept formulation for the Venus In Situ Explorer (VISE) mission. Five primary steps are outlined which encompass program objective definition through evaluation of candidate designs. Tools covered include the Analytic Hierarchy Process (AHP), Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and morphological matrices. Direction is given for the application of modeling and simulation as well as for subsequent iterations of the process. The paper covers both theoretical and practical aspects of the tools and process in the context of the VISE example, and it is hoped that this methodology may find future use in interplanetary probe design.
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ItemDesign of an Entry System for Cargo Delivery to Mars(Georgia Institute of Technology, 2007-06) Thompson, Robert W. ; Cliatt, Larry ; Gruber, Chris ; Steinfeldt, Bradley A. ; Sebastin, Tommy ; Wilson, JamieLong-term human missions to Mars will require the supply of consumables such as food, water, and oxygen. A sustained campaign of Mars exploration, in which astronauts are on the surface for months to years at a time, may require regular supply missions. In this paper, a systems study for an entry vehicle for human resupply cargo delivery to Mars is outlined. The design objectives for such a mission might be to deliver 20 metric tons (MT) of human resupply cargo to the surface of Mars at 0 km altitude (MOLA reference) with a landed accuracy of less than 1 km. The system-level trade studies and configurations considered are discussed and a baseline configuration that satisfies the design objectives is presented. Vehicle analysis includes subsystem mass estimation, propulsion sizing, trajectory simulation, aerothermal analysis, thermal protection system sizing, and cost estimation. Uncertainty analysis is performed through Monte Carlo simulation, and the vehicle is sized to achieve the mission requirements to at least a 99% confidence. Uncertainty in entry parameters is modeled. Additionally, technological development required to enable such a mission is discussed.
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ItemOptimization of Earth Flight Test Trajectories to Qualify Parachutes for Use on Mars(Georgia Institute of Technology, 2007-06) Tanner, Christopher L.This paper presents a simulation designed to optimize Earth flight test trajectories of parachute-payload systems. These trajectories attempt to replicate the conditions experienced by a parachute during supersonic descent through the Martian atmosphere. The critical parameters that need to be closely matched in a supersonic flight test are the peak opening load and the parachute load time history, both of which are key parameters to parachute structural qualification. To investigate the associated Earth flight test requirements, descent trajectories and parachute loading profiles are generated for a 4,000 kg payload using a 30 m nominal diameter disk-gap-band parachute deployed at Mach 3 on Mars. Subsequent Earth flight test trajectories are optimized and compared to the reference Mars cases. Both Mars and Earth simulations use two different parachute loading models: an inflation curve and an apparent mass model. Given the same initial conditions, both models generate similar results, but trajectory optimization using each model generates different Earth flight conditions. Finally, a brief investigation into the aerodynamic heating experienced by a supersonic parachute on both Earth and Mars is performed and compared to observed DGB heating profiles.
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ItemEvaluation of the Mars Pathfinder Parachute Drag Coefficient(Georgia Institute of Technology, 2007-06) Verges, Amanda M. ; Braun, Robert D.Flight reconstruction of the successful landing of the Mars Pathfinder (MPF) mission was performed after landing. During development of the Mars Exploration Rover mission, the MPF parachute drag coefficient was re-examined. Using radar altimeter data, it was determined that the MPF parachute drag coefficient was 0.4133 (based on the parachute’s nominal area), with a 3-sigma uncertainty of 0.0514. This study assumed a quasi-steady state terminal descent, neglecting the effect of the parachute’s continued deceleration. In the present study, the MPF parachute drag coefficient is evaluated using the same radar altimeter data but taking into account the fact that the MPF parachute continued to decelerate during its terminal descent. This deceleration is also evaluated from the radar altimeter data. The present investigation yields a drag coefficient of 0.4419, with a 3-sigma uncertainty of 0.0549. Taking into account the acceleration effect increases the reconstructed value of the drag coefficient by approximately 7 percent. The difference in drag coefficients determined from the two reconstructions is relatively large because the deceleration being experienced by the system at this time is approximately 0.240 m/s2, a relatively significant value in comparison to the acceleration of gravity on Mars (3.7245 m/s2).
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ItemA Survey of Ballute Technology for Aerocapture(Georgia Institute of Technology, 2005-06) Rohrschneider, Reuben R. ; Braun, Robert D.Ballute aerodynamic decelerators have been studied since early in the space age (1960’s), being proposed for aerocapture in the early 1980’s. Significant technology advances in fabric and polymer materials as well as analysis capabilities lend credibility to the potential of ballute aerocapture. The concept of the thin-film ballute for aerocapture shows the potential for large mass savings over propulsive orbit insertion or rigid aeroshell aerocapture. The mass savings of this concept enables a number of high value science missions. Current studies of ballute aerocapture at Titan and Earth may lead to flight test of one or more ballute concepts within the next five years. This paper provides a survey of the literature with application to ballute aerocapture. Special attention is paid to advances in trajectory analysis, hypersonic aerothermodynamics, structural analysis, coupled analysis, and flight tests. Advances anticipated over the next 5 years are summarized.
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ItemDevelopment of a Planetary Entry System Synthesis Tool for Conceptual Design and Analysis(Georgia Institute of Technology, 2005-06) Kipp, Devin M. ; Dec, John A. ; Wells, Grant William ; Braun, Robert D.A Planetary Entry Systems Synthesis Tool, with applications to conceptual design and modeling of entry systems has been developed. This tool is applicable to exploration missions that employ entry, descent and landing or aerocapture. An integrated framework brings together relevant disciplinary analyses and enables rapid design and analysis of the atmospheric entry mission segment. Tool performance has been validated against Mars Pathfinder flight experience and has direct relevance to future NASA robotic and human space exploration systems.