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End date: 2017 × Start date: 2010 × search.filters.applied.f.isOrgUnitOfPublicationTitle: Daniel Guggenheim School of Aerospace Engineering ×

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Now showing 1 - 10 of 64
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    Flyby Trajectory Analysis and Thermal Simulation of a Venus Atmospheric Probe
    (Georgia Institute of Technology, 2017-12-01) Selvaratnam, Roshan
    Cupid’s Arrow is a proposed interplanetary Venus mission aimed at sampling the noble gases in its atmosphere. These inert elements can provide an insight into the history of the planet’s formation and provide a reference for comparison with the Earth. The mission is comprised of a mothership and an atmospheric sample collection probe. This study is focused on the latter which will be deployed into Venus’ atmosphere and descend to an altitude of 120 km. The thermal environment of the Venusian exosphere is the primary driver of the probe design both in terms of its structure and material composition. The mission architecture being considered for this study takes advantage of a gravity assist flyby trajectory. The probe will be dropped off as a secondary payload en route to the spacecraft’s primary destination. The entry conditions at Venus and the trajectory of the probe relative to the mothership were determined using 2-body orbital mechanics. Using planar equations of motion, the probe’s entry into Venus’ atmosphere was simulated to predict the thermal environment that it would encounter. Initial results show a peak heat rate of approximately 220.3297 W/cm2 , a peak deceleration of 2.7654 Earth g’s and a total heat load of 15535 J/cm2 . The results of the thermal environment model and relative trajectory analysis were used to validate the baseline communications and TPS design. In addition to Venus, this mission concept could be used to explore other planetary atmospheres, especially those frequented by interplanetary flybys.
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    An Evaluation of Spacecraft Pointing Requirements for Optically Linked Satellite Systems
    (Georgia Institute of Technology, 2017-08) Dahl, Trevor A.
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    Development of an Earth SmallSat Flight Test to Demonstrate Viability of Mars Aerocapture
    (Georgia Institute of Technology, 2017-05-01) Werner, Michael S.
    A smallsat mission concept is developed to demonstrate the feasibility of an aerocapture system at Earth. The proposed mission utilizes aerocapture to transfer from a GTO rideshare trajectory to a LEO. Single-event drag modulation is used as a simple means of achieving the control required during the maneuver. Low- and high-fidelity guidance algorithm choices are considered. Numeric trajectory simulations and Monte Carlo uncertainty analyses are performed to show the robustness of the system to day-of-flight environments and uncertainties. Similar investigations are performed at Mars to show the relevance of the proposed mission concept to potential future applications. The spacecraft design consists of a 24.9 kg vehicle with an attached rigid drag skirt, and features commercially-available hardware to enable flight system construction at a university scale. Results indicate that the proposed design is capable of targeting the desired final orbit, surviving the aerothermodynamic and deceleration environments produced during aerocapture, and downlinking relevant data following the maneuver
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    Trajectory Trade-space Design for Robotic Entry at Titan
    (Georgia Institute of Technology, 2017-05-01) Roelke, Evan
    In recent years, scientific focus has emphasized other ocean worlds such as Europa, Enceladus, and Titan, due to their potential for harboring life. The only spacecraft ever to land on these moons was the Huygens Probe in 2005; however, this probe’s main purpose was to study the atmosphere and surface of Titan, with no real landing target. Future missions to other ocean worlds would likely require a science target and thus add several constraints to the mission such as arrival time, entry state, and aeroshell geometry, among others. Of the three ocean worlds previously mentioned, Titan is an optimal target for initial mission concepts for several reasons. The atmospheric composition, winds, and surface features are well studied by Cassini and the Huygens Probe. Additionally, of the aforementioned moons, Titan does not have a thick ice sheet to penetrate in order to sample the surface and/or liquid seas, enabling such mission to double as a stepping stone for missions to other ocean worlds. Finally, Titan exhibits a myriad of interesting planetary features that, if studied, could further the understanding of both Titan’s and the solar system’s geologic history. In this paper we analyze the trade-spaces of various important parameters involved in Entry, Descent, and Landing (EDL) as it pertains to robotic missions for Titan in order to provide a guideline for optimizing a mission’s system parameters while minimizing both system complexity and the landing footprint. It is found that the ideal geometry is a ballistic spherecone body entering from orbit to allow flexibility in the entry state vector. The aerothermodynamic environment is most affected by the entry velocity and the vehicle bluntness ratio, while the peak deceleration is most influenced by the entry velocity and entry flight path angle. In addition, multiple parachutes decrease the landing footprint, impact speed, and descent time compared to single parachute systems, at the expense of being more complex. Larger ballistic coefficients decrease the landing footprint and descent time while increasing the impact speed. Finally, it is discovered that the uncertainty in the entry altitude and flight path angle have the most impact on the final state vector.
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    User Guide and Status Update for Small Satellite Communication System at Georgia Tech
    (Georgia Institute of Technology, 2017-04-28) Choi, Thomas
    The Georgia Institute of Technology (Georgia Tech) is scheduled to support five different small satellite missions within the next three-year frame (2017 to 2020). Because many missions will share the same ground station system, a flexible and reliable ground station system has been developed at Georgia Tech campus and Georgia Tech Research Institute facility since Fall 2015. In addition to the missions expected to fly, more mission concepts are being developed which could be funded and become actual flight missions. Proper trade study and budgeting is necessary to select a proper communication hardware and establish a link that is functional and efficient. This paper is written to provide a user guide for current and potential communication subsystem engineers for small satellite mission teams at Georgia Tech, who will utilize the ground station system, select flight hardware according to requirements, and test communication links.
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    An Evaluation of Spacecraft Pointing Requirements for Optically Linked Satellite Systems
    (Georgia Institute of Technology, 2017-04-08) Dahl, Trevor A.
    This study evaluates pointing requirements for free space optical data links of a satellite network. For many applications, optical links pose a distinct advantage over radio frequency (RF) links for their far higher data transmission rates. They can also be much lighter than RF antennas and require far less power, making them ideal transmission methods for small satellites and CubeSats. While more power efficiency is achieved thru narrow beam divergence, the narrower beams pose a technical challenge due to the higher pointing accuracy required for effective transmission. A general method for characterizing pointing tolerance, angular rates and angular accelerations for Line-of-Site (LoS) vectors is devised. Several case studies involving different (single-layer) constellation designs were evaluated. Varying degrees of inclination and offset of true anomaly from one plane to a connecting plane were evaluated and corresponding angular velocity and accelerations are reported. The study finds that the methodology outlined gives crucial information to assess pointing requirements against various constellation designs. This assessment can then drive the trade space for designs for optically linked networks from the hardware aboard each satellite, to the design of the satellite constellation itself.
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    The Development and Characterization of the Laser Ranging System on the RANGE CubeSat Mission
    (Georgia Institute of Technology, 2016-12-15) Levine, Zachary A.
    In Spring 2016, Georgia Tech Space Systems Design Laboratory (SSDL) will begin operations on the Ranging And Nanosatellite Guidance Experiment (RANGE) Mission. A crucial element of this mission is the Inter satellite ranging system. This system will determine the relative distance between the two RANGE sister CubeSats providing validation that such a system can function in orbit on a CubeSat. This document describes the factors considered in choosing the Voxtel Laser Range Finder (LRF) Module as the flight unit for both satellites, the integration and testing of this system, and the preliminary analysis of laboratory testing data to predict on-orbit performance.
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    Initial Characterization for LIDAR Remote Sensing from an UAV Platform
    (Georgia Institute of Technology, 2016-12) Lacerda, Michel Alves
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    Initial Characterization for LIDAR Remote Sensing from an UAV Platform
    (Georgia Institute of Technology, 2016-12) Lacerda, Michel Alves
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    Design and Application of a Circular Aperture Sun Sensor
    (Georgia Institute of Technology, 2016-12) Herman, Michael