<?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>2026-09-19T01:45:29Z</responseDate><request verb="GetRecord" identifier="oai:dspace.mit.edu:1721.1/77794" metadataPrefix="dim">https://dspace.mit.edu/server/oai/request</request><GetRecord><record><header><identifier>oai:dspace.mit.edu:1721.1/77794</identifier><datestamp>2022-01-13T07:54:24Z</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">Maria T. Zuber.</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="author" lang="en_US">Talpe, Matthieu Jean</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="other" lang="en_US">Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.</dim:field>
   <dim:field mdschema="dc" element="contributor" qualifier="department">Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="accessioned">2013-03-13T15:47:48Z</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="available">2013-03-13T15:47:48Z</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="copyright" lang="en_US">2012</dim:field>
   <dim:field mdschema="dc" element="date" qualifier="issued" lang="en_US">2012</dim:field>
   <dim:field mdschema="dc" element="identifier" qualifier="uri">http://hdl.handle.net/1721.1/77794</dim:field>
   <dim:field mdschema="dc" element="identifier" qualifier="oclc" lang="en_US">828103661</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2012.</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Cataloged from PDF version of thesis.</dim:field>
   <dim:field mdschema="dc" element="description" lang="en_US">Includes bibliographical references (p. 51-55).</dim:field>
   <dim:field mdschema="dc" element="description" qualifier="abstract" lang="en_US">Recently acquired altimetry data from laser altimeters are used to assess the morphometry of impact craters. Data acquired by the Mercury Laser Altimeter on the MESSENGER spacecraft are used to measure the depths and diameters of 537 craters at the high northern latitudes on Mercury, including 42 polar-deposit-hosting craters (PDCs) which host material that is bright to earth-based radar observations. A comparative analysis suggests that the radar-bright material forms a thin (&lt; 20 m) layer emplaced preferentially in comparatively young craters, contradicting an earlier morphometric study that indicated that PDCs contained a thick layer of water ice and dust. Topographic datasets from the lunar surface, collected by the Lunar Orbiter Laser Altimeter onboard the LRO spacecraft, are also used to evaluate the morphometry of 1,356 lunar craters. We study the morphologic change between the simple and complex crater regime, a manifestation of the transition between gravity-dominated and strength-dominated impact-forming processes, on the Moon and Mercury. The Moons transition diameter is near 16 km, in line with previous studies, while Mercurys is near 8 km, 2 km smaller than previously determined. The onset of gravity-dominated mechanisms scales inversely with gravity, which explains why Mercurys transition diameter is approximately half of the Moons.</dim:field>
   <dim:field mdschema="dc" element="description" qualifier="statementofresponsibility" lang="en_US">by Matthieu Jean Talpe.</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">55 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 
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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">Earth, Atmospheric, and Planetary Sciences.</dim:field>
   <dim:field mdschema="dc" element="title" lang="en_US">Characterization of crater morphometry on the Moon and Mercury from altimetry observations</dim:field>
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   	&lt;Title>Characterization of crater morphometry on the Moon and Mercury from altimetry observations&lt;/Title>
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   	&lt;PublicationDate>2012&lt;/PublicationDate>
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        	&lt;DisplayName>Talpe, Matthieu Jean&lt;/DisplayName>
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    &lt;Keyword>Earth, Atmospheric, and Planetary Sciences.&lt;/Keyword>
   	&lt;Abstract>Recently acquired altimetry data from laser altimeters are used to assess the morphometry of impact craters. Data acquired by the Mercury Laser Altimeter on the MESSENGER spacecraft are used to measure the depths and diameters of 537 craters at the high northern latitudes on Mercury, including 42 polar-deposit-hosting craters (PDCs) which host material that is bright to earth-based radar observations. A comparative analysis suggests that the radar-bright material forms a thin (&amp;lt; 20 m) layer emplaced preferentially in comparatively young craters, contradicting an earlier morphometric study that indicated that PDCs contained a thick layer of water ice and dust. Topographic datasets from the lunar surface, collected by the Lunar Orbiter Laser Altimeter onboard the LRO spacecraft, are also used to evaluate the morphometry of 1,356 lunar craters. We study the morphologic change between the simple and complex crater regime, a manifestation of the transition between gravity-dominated and strength-dominated impact-forming processes, on the Moon and Mercury. The Moons transition diameter is near 16 km, in line with previous studies, while Mercurys is near 8 km, 2 km smaller than previously determined. The onset of gravity-dominated mechanisms scales inversely with gravity, which explains why Mercurys transition diameter is approximately half of the Moons.&lt;/Abstract>
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