<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-09-19T10:10:41Z</responseDate><request verb="GetRecord" identifier="oai:dspace.mit.edu:1721.1/79333" metadataPrefix="dim">https://dspace.mit.edu/server/oai/request</request><GetRecord><record><header><identifier>oai:dspace.mit.edu:1721.1/79333</identifier><datestamp>2022-01-13T07:53:53Z</datestamp><setSpec>com_1721.1_7582</setSpec><setSpec>com_1721.1_7581</setSpec><setSpec>col_1721.1_131023</setSpec></header><metadata><dim:dim xmlns:dim="http://www.dspace.org/xmlns/dspace/dim" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.dspace.org/xmlns/dspace/dim http://www.dspace.org/schema/dim.xsd">
   <dim:field mdschema="dc" element="contributor" qualifier="advisor" lang="en_US">Kerri Cahoy.</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="author" lang="en_US">Lohmeyer, Whitney Quinne</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="other" lang="en_US">Massachusetts Institute of Technology. Department of Aeronautics and Astronautics.</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="department">Massachusetts Institute of Technology. Department of Aeronautics and Astronautics</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="accessioned">2013-06-17T20:05:05Z</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="available">2013-06-17T20:05:05Z</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="copyright" lang="en_US">2013</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="issued" lang="en_US">2013</dim:field>
   <dim:field mdschema="dc" element="identifier" qualifier="uri">http://hdl.handle.net/1721.1/79333</dim:field>
   <dim:field mdschema="dc" element="identifier" qualifier="oclc" lang="en_US">845062544</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project.  The certified thesis is available in the Institute Archives and Special Collections.</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Cataloged from department-submitted PDF version of thesis.</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Includes bibliographical references (p. 86-89).</dim:field>
   <dim:field mdschema="dc" element="description" qualifier="abstract" lang="en_US">To understand and mitigate the effects of space weather on the performance of geostationary communications satellites, we analyze sixteen years of archived telemetry data from Inmarsat, the UK-based telecommunications company, and compare on-orbit anomalies with space weather observations. Data from multiple space weather sources, such as the Geostationary Operational Environmental Satellites (GOES), are compared with Inmarsat anomalies from 1996 to 2012. The Inmarsat anomalies include 26 solid-state power amplifier (SSPA) anomalies and 226 single event upsets (SEUs). We first compare SSPA anomalies to the solar and geomagnetic cycle. We find most SSPA anomalies occur as solar activity declines, and when geomagnetic activity is low. We compare GOES 2 MeV electron flux and SSPA current for two weeks surrounding each anomaly. Seventeen of the 26 SSPA anomalies occur within two weeks after a severe space weather event. Fifteen of these 17 occur after relativistic electron events. For these fifteen, peak electron flux occurs a mean of 8 days and standard deviation of 4.7 days before the anomaly. Next, we examine SEUs, which are unexpected changes in a satellite's electronics, such as memory changes or trips in power supplies. Previous research has suggested that solar energetic protons (SEPs) cause SEUs. However, we find that SEUs for one generation of satellites are uniformly distributed across the solar cycle. SEUs for a second generation of satellites, for which we currently have only half a solar cycle of data, occur over an order of magnitude more often than the first, even during solar minimum. This suggests that SEPs are not the primary cause of SEUs, and that occurrence rates differ substantially for different satellite hardware platforms with similar functionality in the same environment. These results will guide design improvements and provide insight on operation of geostationary communications satellites during space weather events.</dim:field>
   <dim:field mdschema="dc" element="description" qualifier="statementofresponsibility" lang="en_US">by Whitney Quinne Lohmeyer.</dim:field>
   <dim:field mdschema="dc" element="description" qualifier="degree" lang="en_US">S.M.</dim:field>
   <dim:field mdschema="dc" element="format" qualifier="extent" lang="en_US">89 p.</dim:field>
   <dim:field mdschema="dc" element="language" qualifier="iso" lang="en_US">eng</dim:field>
   <dim:field mdschema="dc" element="publisher" lang="en_US">Massachusetts Institute of Technology</dim:field>
   <dim:field mdschema="dc" element="rights" lang="en_US">M.I.T. theses are protected by 
copyright. They may be viewed from this source for any purpose, but 
reproduction or distribution in any format is prohibited without written 
permission. See provided URL for inquiries about permission.</dim:field>
   <dim:field mdschema="dc" element="rights" qualifier="uri" lang="en_US">http://dspace.mit.edu/handle/1721.1/7582</dim:field>
   <dim:field mdschema="dc" element="subject" lang="en_US">Aeronautics and Astronautics.</dim:field>
   <dim:field mdschema="dc" element="title" lang="en_US">Data management of geostationary communication satellite telemetry and correlation to space weather observations</dim:field>
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   	&lt;Title>Data management of geostationary communication satellite telemetry and correlation to space weather observations&lt;/Title>
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   	&lt;PublicationDate>2013&lt;/PublicationDate>
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    &lt;Keyword>Aeronautics and Astronautics.&lt;/Keyword>
   	&lt;Abstract>To understand and mitigate the effects of space weather on the performance of geostationary communications satellites, we analyze sixteen years of archived telemetry data from Inmarsat, the UK-based telecommunications company, and compare on-orbit anomalies with space weather observations. Data from multiple space weather sources, such as the Geostationary Operational Environmental Satellites (GOES), are compared with Inmarsat anomalies from 1996 to 2012. The Inmarsat anomalies include 26 solid-state power amplifier (SSPA) anomalies and 226 single event upsets (SEUs). We first compare SSPA anomalies to the solar and geomagnetic cycle. We find most SSPA anomalies occur as solar activity declines, and when geomagnetic activity is low. We compare GOES 2 MeV electron flux and SSPA current for two weeks surrounding each anomaly. Seventeen of the 26 SSPA anomalies occur within two weeks after a severe space weather event. Fifteen of these 17 occur after relativistic electron events. For these fifteen, peak electron flux occurs a mean of 8 days and standard deviation of 4.7 days before the anomaly. Next, we examine SEUs, which are unexpected changes in a satellite&amp;apos;s electronics, such as memory changes or trips in power supplies. Previous research has suggested that solar energetic protons (SEPs) cause SEUs. However, we find that SEUs for one generation of satellites are uniformly distributed across the solar cycle. SEUs for a second generation of satellites, for which we currently have only half a solar cycle of data, occur over an order of magnitude more often than the first, even during solar minimum. This suggests that SEPs are not the primary cause of SEUs, and that occurrence rates differ substantially for different satellite hardware platforms with similar functionality in the same environment. These results will guide design improvements and provide insight on operation of geostationary communications satellites during space weather events.&lt;/Abstract>
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