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Articles 61 - 72 of 72
Full-Text Articles in Astrodynamics
Design, Fabrication, And Testing Of An Electromagnetic Rail Gun For The Repeated Testing And Simulation Of Orbital Debris Impacts, Jeff Maniglia, Jordan Smiroldo, Alex Westfall, Guy Zohar
Design, Fabrication, And Testing Of An Electromagnetic Rail Gun For The Repeated Testing And Simulation Of Orbital Debris Impacts, Jeff Maniglia, Jordan Smiroldo, Alex Westfall, Guy Zohar
Aerospace Engineering
An Electromagnetic Railgun (EMRG) was designed, built, and tested, capable of firing a projectile a 1 gram projectile at 650 m/s muzzle velocity. The EMRG utilizes an injector, a high voltage power supply, a capacitor bank, inductors and rails. The injector fires 2300 psig Nitrogen gas into the system to provide an initial velocity. The high voltage power supply charges the capacitor bank. The capacitor bank discharges the electric potential built up through the projectile while inside the rails in order to create the EMRG’s force. The inductors are used to pulse form the capacitor bank in order to get …
An Analysis Of Stabilizing 3u Cubesats Using Gravity Gradient Techniques And A Low Power Reaction Wheel, Erich Bender
An Analysis Of Stabilizing 3u Cubesats Using Gravity Gradient Techniques And A Low Power Reaction Wheel, Erich Bender
Aerospace Engineering
The purpose of this paper is to determine the feasibility of gravity gradient stabilizing a 3U CubeSat and then using a miniature reaction wheel to further increase stability characteristics. This paper also serves as a guide to understanding and utilizing quaternions in attitude control analysis. The analytical results show that using 33 centimeter booms and 400 gram tip masses, a 3U CubeSat will experience a maximum of 6 degrees of angular displacement in yaw and pitch, and less than .5 degrees of angular displacement in the nadir axis. A .120 kilogram miniature reaction wheel developed by Sinclair Interplanetary was introduced …
An Analysis Of N-Body Trajectory Propagation, Emerson Frees Ii
An Analysis Of N-Body Trajectory Propagation, Emerson Frees Ii
Aerospace Engineering
Trajectories created with n-body orbit models were propagated in geocentric and interplanetary test cases. The n-body models were created in MATLAB® using numerical integration. In the geocentric test case, the n-body codes were compared to a two-body orbit model and to the default HPOP model used in Satellite Tool Kit®. The interplanetary test case compared the n-body model to the HORIZONS ephemeris data from JPL and an equation for ephemeris propagation. Both cases used the same initial positions and velocities and were propagated for the same duration. The results of the analysis showed that while n-body models …
Mapping Galileo's Trajectory, Mark Woods
Mapping Galileo's Trajectory, Mark Woods
Aerospace Engineering
The NASA Galileo mission was mapped out using a patched conics approximation. Galileo launched from Earth, underwent a gravity assist from Venus back to Earth for another gravity assist. Galileo then came back to Earth for one more gravity assist to propel it to Jupiter. A simulation ignoring all perturbations (i.e. third body effects, zonal (harmonics, solar wind, drag) was carried out. The simulation was able to make it to the final Earth flyby before diverging from the actual trajectory. The simulated and actual flyby dates all differed by less than 5 hours, and the simulated and actual flyby altitudes …
Modeling And Simulation Of Autonomous Thermal Soaring With Horizon Simulation Framework, Zhenhua Li
Modeling And Simulation Of Autonomous Thermal Soaring With Horizon Simulation Framework, Zhenhua Li
Master's Theses
A thermal is a column of warm rising air triggered by differential heating on the ground. In recent studies UAVs were programmed to exploit this free atmospheric energy from thermals to improve their range and endurance. Researchers had successfully flown UAVs autonomously with thermal soaring method. Most research involved some form of flight simulation. Improvements to the aircraft and thermal models for simulation purpose would enable researchers to better design their UAVs and explore any potential flaws in their designs. An aircraft simulation with a thermal environment was created in Horizon Simulation Framework, a modeling and verification framework that was …
Interplanetary Gravity Assisted Trajectory Optimizer (Igato), Jason Bryan
Interplanetary Gravity Assisted Trajectory Optimizer (Igato), Jason Bryan
Aerospace Engineering
Interplanetary space travel is an extremely complicated endeavor that is severely limited by our current technological advancements. The amount of energy required to transport a spacecraft from one planet to the next, or even further, is extraordinary and in some cases is even impossible given our current propulsive capabilities. Due to these complications, the search for other means of exchanging energy became imperative to future space exploration missions. One particularly powerful method that was discovered, and the most commonly used one, is referred to as planetary gravity assist. In order to plan out multiple gravity assist trajectories, complex and robust …
Senior Project: Global Position Determination From Observed Relative Position Of Celestial Bodies, Michael Holmes
Senior Project: Global Position Determination From Observed Relative Position Of Celestial Bodies, Michael Holmes
Aerospace Engineering
A method was developed to determine the latitude and longitude of an observer based on the observed position of the Moon and several other celestial bodies. The basic principal developed dealt with the proximity of the Moon. Its relative displacement from calculated values was measured using photography by comparison with stars near the Moon. Photographs were taken from a location in San Luis Obispo at Longitude 120°35.9' and Latitude 35°13.3'. The analysis method has determined the location of the observer to a Longitude of 117°43.8'. An additional method located the observer to 36°38.7'N Latitude and 114°47.6'W Longitude.
Matlab® Gui Visualization Of Classical Orbital Elements, Nancy Teresa Cabrera
Matlab® Gui Visualization Of Classical Orbital Elements, Nancy Teresa Cabrera
Aerospace Engineering
The classical orbital elements of an orbit are eccentricity, angular momentum, inclination, right ascension of ascending node, true anomaly, and argument of perigee. These six parameters define an orbit. Using MATLAB® to model a satellite orbiting Earth in three dimensions, a graphical user interface was created to allow a user to manipulate the orbital elements to desired quantities. In doing so, each parameter’s impact on the orbit is visually displayed. This furthers the understanding of how the parameters are linked to the orbit. When the interface is first opened, the default circular orbit has a range of 20,000 kilometers, an …
System Integration And Attitude Control Of A Low-Cost Spacecraft Attitude Dynamics Simulator, Ryan L. Kinnett
System Integration And Attitude Control Of A Low-Cost Spacecraft Attitude Dynamics Simulator, Ryan L. Kinnett
Master's Theses
The CalPoly Spacecraft Attitude Dynamics Simulator mimics the rotational dynamics of a spacecraft in orbit and acts as a testbed for spacecraft attitude control system development and demonstration. Prior to this thesis, the simulator platform and several subsystems had been designed and manufactured, but the total simulator system was not yet capable of closed-loop attitude control. Previous attempts to make the system controllable were primarily mired by data transport performance. Rather than exporting data to an external command computer, the strategy implemented in this thesis relies on a compact computer onboard the simulator platform to handle both attitude control processing …
Adaptive Control Applied To The Cal Poly Spacecraft Attitude Dynamics Simulator, Matthew C. Downs
Adaptive Control Applied To The Cal Poly Spacecraft Attitude Dynamics Simulator, Matthew C. Downs
Master's Theses
The goal of this thesis is to use the Cal Poly Spacecraft Attitude Dynamics Simulator to provide proof of concept of two adaptive control theories developed by former Cal Poly students: Nonlinear Direct Model Reference Adaptive Control and Adaptive Output Feedback Control. The Spacecraft Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft scenario, and under simulated actuator damage. Proof of concept of the adaptive control theories applied to attitude …
Orbital Propagators For Horizon Simulation Framework, Mitra Farahmand
Orbital Propagators For Horizon Simulation Framework, Mitra Farahmand
Master's Theses
This thesis describes the models of four common orbital propagators and outlines the process of integrating them into the Horizon Simulation Framework (HSF). The results of the Two-Body, J2, and J4 propagators from the HSF are then compared against the outcomes of these propagators in MATLAB and Satellite Toolkit (STK). The MATLAB algorithms verify the functionality of the propagators and determine the accuracy of the HSF implementation. The compassion against STK validates the formulation of the HSF propagators. In order to equip the HSF with a more precise means of orbit determination, adding the Simplified General Perturbations 4 (SGP4) propagator …
Comparison And Design Of Simplified General Perturbation Models (Sgp4) And Code For Nasa Johnson Space Center, Orbital Debris Program Office, Nicholas Z. Miura
Comparison And Design Of Simplified General Perturbation Models (Sgp4) And Code For Nasa Johnson Space Center, Orbital Debris Program Office, Nicholas Z. Miura
Master's Theses
This graduate project compares legacy simplified general perturbation model (SGP4) code developed by NASA Johnson Space Center, Orbital Debris Program Office, to a recent public release of SGP4 code by David Vallado. The legacy code is a subroutine in a larger program named PREDICT, which is used to predict the location of orbital debris in GEO. Direct comparison of the codes showed that the new code yields better results for GEO objects, which are more accurate by orders of magnitude (error in meters rather than kilometers). The public release of SGP4 also provides effective results for LEO and MEO objects …