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dc.contributor.advisorSubbarao, Kamesh
dc.creatorPerez, Tracie Renea Conn
dc.date.accessioned2017-02-14T16:43:16Z
dc.date.available2017-02-14T16:43:16Z
dc.date.created2016-12
dc.date.issued2017-01-02
dc.date.submittedDecember 2016
dc.identifier.urihttp://hdl.handle.net/10106/26441
dc.description.abstractOver the past 15 years, there has been a growing interest in femtosatellites, a class of tiny satellites having mass less than 100 grams. Research groups from Peru, Spain, England, Canada, and the United States have proposed femtosat designs and novel mission concepts for them. In fact, Peru made history in 2013 by releasing the first – and still only – femtosat tracked from LEO. However, femtosatellite applications in interplanetary missions have yet to be explored in detail. An interesting operations concept would be for a space probe to release numerous femtosatellites into orbit around a planetary object of interest, thereby augmenting the overall data collection capability of the mission. A planetary probe releasing hundreds of femtosats could complete an in-situ, simultaneous 3D mapping of a physical property of interest, achieving scientific investigations not possible for one probe operating alone. To study the technical challenges associated with such a mission, a conceptual mission design is proposed where femtosats are deployed from a host satellite orbiting Titan. The conceptual mission objective is presented: to study Titan's dynamic atmosphere. Then, the design challenges are addressed in turn. First, any science payload measurements that the femtosats provide are only useful if their corresponding locations can be determined. Specifically, what's required is a method of position determination for femtosatellites operating beyond Medium Earth Orbit and therefore beyond the help of GPS. A technique is presented which applies Kalman filter techniques to Doppler shift measurements, allowing for orbit determination of the femtosats. Several case studies are presented demonstrating the usefulness of this approach. Second, due to the inherit power and computational limitations in a femtosatellite design, establishing a radio link between each chipsat and the mothersat will be difficult. To provide a mathematical gain, a particular form of forward error correction (FEC) method called low-density parity-check (LDPC) codes is recommended. A specific low-complexity encoder, and accompanying decoder, have been implemented in the open-source software radio library, GNU Radio. Simulation results demonstrating bit error rate (BER) improvement are presented. Hardware for implementing the LDPC methods in a benchtop test are described and future work on this topic is suggested. Third, the power and spatial constraints of femtosatellite designs likely restrict the payload to one or two sensors. Therefore, it is desired to extract as much useful scientific data as possible from secondary sources, such as radiometric data. Estimating the atmospheric density model from different measurement sources is simulated; results are presented. The overall goal for this effort is to advance the field of miniature spacecraft-based technology and to highlight the advantages of using femtosatellites in future planetary exploration missions. By addressing several subsystem design challenges in this context, such a femtosat mission concept is one step closer to being feasible.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.subjectFemtosat
dc.subjectFemtosatellite
dc.subjectTitan
dc.subjectOrbit determination
dc.subjectSmall satellite
dc.subjectPlanetary exploration
dc.subjectLDPC
dc.subjectLow density parity check
dc.subjectForward error correction
dc.subjectGNU Radio
dc.subjectDoppler
dc.subjectKalman filter
dc.titleA FRAMEWORK FOR EMPLOYING FEMTOSATELLITES IN PLANETARY SCIENCE MISSIONS, INCLUDING A PROPOSED MISSION CONCEPT FOR TITAN
dc.typeThesis
dc.contributor.committeeMemberHarris, Ben
dc.contributor.committeeMemberWilson, Donald R.
dc.degree.departmentMechanical and Aerospace Engineering
dc.degree.nameDoctor of Philosophy in Aerospace Engineering
dc.date.updated2017-02-14T16:43:16Z
thesis.degree.departmentMechanical and Aerospace Engineering
thesis.degree.grantorThe University of Texas at Arlington
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy in Aerospace Engineering
dc.type.materialtext
dc.creator.orcid0000-0002-7353-8085


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