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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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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.