Organizational Unit:

Daniel Guggenheim School of Aerospace Engineering

Permanent Link

https://hdl.handle.net/1853/70742

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Organizational Unit

College of Engineering

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Organizational Unit

Aerospace Design Group

Organizational Unit

Aerospace Systems Design Laboratory (ASDL)

Organizational Unit

Air Transportation Laboratory

Organizational Unit

Cognitive Engineering Center

Organizational Unit

Space Systems Design Laboratory (SSDL)

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ArchiveSpace Name Record

https://finding-aids.library.gatech.edu/agents/corporate_entities/106

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Publication Search Results

Now showing 1 - 10 of 34

Analytic Free-Molecular Aerodynamics for Rapid Propagation of Resident Space Objects

(American Institute of Aeronautics and Astronautics, 2018-01) Hart, Kenneth A. ; Simonis, Kyle R. ; Steinfeldt, Bradley A. ; Braun, Robert D.

Aerodynamic forces and moments are significant perturbations on low-Earth-orbiting objects, second in magnitude to the nonspherical gravity field. Traditionally, the aerodynamic perturbations are calculated using a direct simulation Monte Carlo method. Under certain assumptions, these forces and moments can be described analytically via free-molecular flow theory. Using symbolic manipulation techniques, exact expressions for the free-molecular aerodynamics of analytic shapes can be derived. In this investigation, analytic expressions for the aerodynamic force and moment coefficients of primitive and composite parametric surfaces are derived, then validated against industry-standard direct simulation Monte Carlo techniques. A framework for the rapid and accurate calculation of free-molecular aerodynamics of composite geometries based on superposition is described. This framework is applied to axisymmetric composite geometries. Results within 6% of direct simulation Monte Carlo calculations are obtained in 0.05% of the time. The analytic aerodynamics models enable rapid trajectory and uncertainty propagation for low-Earth-orbiting objects. A case study on aerodynamic perturbations of a low-Earth-orbit nanosatellite is included to demonstrate application of these analytic models. The case study shows that these derived analytical free-molecular aerodynamics produce results that are applicable to inclusion in rapid trajectory propagation tools for orbit prediction and conceptual mission design. Item Description: Analytic hypersonic rarefied aerodynamics paper published in the Journal of Spacecraft in Rockets, with primary application being resident space objects in low-Earth orbit. Supplemental CDF file contains equations that would not fit in full paper.
IAD wind-tunnel test data analysis & IAD structural modeling

(Georgia Institute of Technology, 2010-12-31) Jagoda, Jechiel I. ; Tanner, Chris ; Braun, Robert D.
Georgia Tech contributions to the H&RT ultra lightweight, inflatable ...

(Georgia Institute of Technology, 2009-07-14) Braun, Robert D.
Development of a conceptual design mission analysis system for guided entry systems

(Georgia Institute of Technology, 2008-06-30) Braun, Robert D.
Entry, 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.
Introducing PESST: A Conceptual Design and Analysis Tool for Unguided/Guided EDL Systems

(Georgia Institute of Technology, 2008-06-24) Otero, Richard ; Grant, Michael ; Steinfeldt, Brad ; Braun, Robert D.

The Planetary Entry Systems and Synthesis Tool (PESST) has been under development at the Space Systems Design Laboratory (SSDL) for several years. This framework has the capability to estimate the performance and mass of a hypersonic vehicle using user-defined geometry, hypersonic aerodynamics, flight mechanics, selectable guidance, thermal response and mass estimation. Earth and Mars atmospheres are preloaded with the ability to also use either user-defined or GRAM atmospheric models. Trade studies can be performed by parameter sweeps to gain an excellent understanding of the design space for conceptual studies. This framework is broadly applicable to conceptual studies of EDL, aerocapture and precision and/or pin point landing systems.
Planetary entry system synthesis tool, a method for hypersonic aerodynamic shape optimization

(Georgia Institute of Technology, 2008-03-31) Braun, Robert D. ; Theisinger, John E.
Trajectory simulation tool for the assessment of viable planetary defense ...

(Georgia Institute of Technology, 2007-12-12) Braun, Robert D. ; Stahl, Benjamin Andrew
Technology Readiness Level, Schedule Risk and Slippage in Spacecraft Design: Data Analysis and Modeling

(Georgia Institute of Technology, 2007-09) Dubos, Gregory F. ; Saleh, Joseph H. ; Braun, Robert D.

Schedule slippage plagues the space industry, and is antinomic with the recent emphasis on space responsiveness. The Government Accountability Office has repeatedly noted the difficulties encountered by the Department of Defense in keeping its acquisition of space systems on schedule, and identified the low Technology Readiness Level (TRL) of the system/payload under development as a principal culprit driving schedule risk and slippage. In this paper, we analyze based on data from past space programs the relationship between technology uncertainty and schedule risk in the acquisition of space systems, and propose an analytical framework to identify appropriate schedule margins for mitigating the risk of schedule slippage. We also introduce the TRL-schedule-risk curves to help program managers make riskinformed decisions regarding the appropriate schedule margins for a given program, or the appropriate TRL to consider should the program’s schedule be exogenously and rigidly constrained. We recommend based on our findings, that the industry adopts and develops schedule risk curves (instead of single schedule point estimates), 2) that these schedule risk curves be made available to policy- and decision-makers in acquisition programs; and 3) that adequate schedule margins be defined according to an agreed upon and acceptable schedule risk level.
Design Space Pruning Techniques for Low-Thrust, Multiple Asteroid Rendezvous Trajectory Design

(Georgia Institute of Technology, 2007-09) Alemany, Kristina ; Braun, Robert D.

In 2006, the 2nd Global Trajectory Optimization Competition (GTOC2) posed a “Grand Asteroid Tour” trajectory optimization problem, where participants were required to find the best possible low-thrust trajectory that would rendezvous with one asteroid from each of four defined groups. As a first step, most teams employed some form of design space pruning, in order to reduce the overall number of possible asteroid combinations. Because of the large size of the problem, teams were not able to determine if their pruning technique had successfully eliminated only bad solutions from the design space. Therefore, a small subset of the GTOC2 problem was analyzed, and several design space pruning techniques were applied to determine their effectiveness. The results indicate that the pruning techniques chosen by the participants likely eliminated good solutions from the design space, because they either did not accurately represent the low-thrust problem or could not be considered independently without the effect of other factors.