<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"><meta http-equiv="Content-Type" content="text/html charset=us-ascii"><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="font-family: Helvetica; "></span><span style="letter-spacing: 0.0px">* <b>MESSENGER</b> - September 21, 2012</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px"><b>MESSENGER's X-Ray Spectrometer Reveals Chemical Diversity on Mercury's Surface</b></span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">"New data from the X-Ray Spectrometer (XRS) on the MESSENGER spacecraft -- one of two instruments designed to measure the abundances of many key elements on Mercury -- show variations in the composition of surface material on Mercury that point to changes over time in the characteristics of volcanic eruptions on the solar system's innermost planet.</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">In results to be published in the Journal of Geophysical Research, scientists report that Mercury's volcanic smooth plains units differ in composition from older surrounding terrains. The older terrain has higher ratios of magnesium to silicon, sulfur to silicon, and calcium to silicon, but lower ratios of aluminum to silicon, suggesting that the smooth plains material erupted from a magma source that was chemically different from the source of the material in the older regions, explains Shoshana Weider of the Carnegie Institution of Washington, the lead author on the paper.</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">"The new findings further illuminate the geological history of the planet," she says. "We now know that these areas are compositionally distinct, indicating that different parts of Mercury's mantle melted at different times and temperatures, and through volcanic activity created the materials in the different terrains."</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">Weider and her co-authors also report that Mercury's surface is dominated by minerals high in magnesium and enriched in sulfur. </span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">"None of the other terrestrial planets have such high levels of sulfur. We are seeing about ten times the amount of sulfur than on Earth and Mars," Weider says. "In terms of magnesium, we do have some materials on Earth that are high in magnesium. They tend to be ancient volcanic rocks that formed from very hot lavas. So this composition on Mercury tells us that eruptions of high-temperature lavas might have formed these high-magnesium materials."</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; color: rgb(2, 30, 170); "><span style="letter-spacing: 0.0px; color: #000000">The new app is available for download at <a href="http://itunes.apple.com/us/app/messenger-nasas-mission-to/id510144229?ls=1&mt=8"><span style="letter-spacing: 0px; ">http://itunes.apple.com/us/app/messenger-nasas-mission-to/id510144229?ls=1&mt=8</span>.</a></span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">For more information on the MESSENGER mission, visit the MESSENGER home page: <a href="http://messenger.jhuapl.edu/"><span style="letter-spacing: 0px; color: rgb(4, 51, 255); ">http://messenger.jhuapl.edu/</span></a>.</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">* <b>Pack Your Backpack</b></span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">Calling all explorers! Tour JPL with our new Virtual Field Trip site. Stops include Mission Control and the Rover Lab. Your guided tour starts when you select a "face" that will be yours throughout the visit. Cool space images and souvenirs are all included in your visit.</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; color: rgb(4, 51, 255); "><span style="letter-spacing: 0.0px; color: #000000">+ <a href="http://virtualfieldtrip.jpl.nasa.gov/"><span style="letter-spacing: 0px; ">http://virtualfieldtrip.jpl.nasa.gov/</span></a> </span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">* Past, Present, Future and Proposed JPL Missions - <a href="http://www.jpl.nasa.gov/missions"><span style="letter-spacing: 0px; color: rgb(4, 51, 255); ">http://www.jpl.nasa.gov/missions</span></a>.</span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; "><span style="letter-spacing: 0.0px">* For special JPL programs and presentations in your area visit the JPL Solar System Ambassador web site at <a href="http://www2.jpl.nasa.gov/ambassador/index.html"><span style="letter-spacing: 0px; color: rgb(4, 51, 255); ">http://www2.jpl.nasa.gov/ambassador/index.html</span></a>.</span></div><div style="margin: 0px; text-align: center; font-size: 24px; font-family: Courier; "><span style="letter-spacing: 0.0px"><b>Mars Missions</b></span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"><b></b></span><br></div><div style="margin: 0px; text-align: center; font-size: 18px; font-family: Courier; color: rgb(2, 30, 170); "><span style="text-decoration: underline ; letter-spacing: 0.0px"><a href="http://beamartian.jpl.nasa.gov/welcome"><b><i>Be A Martian</i></b><span style="letter-spacing: 0px; color: rgb(2, 30, 170); "><b><i></i></b></span></a></span></div><div style="margin: 0px; font-size: 12px; font-family: Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"><b></b></span><br></div><div style="margin: 0px; font-size: 12px; font-family: Courier; color: rgb(4, 51, 255); "><span style="font-family: Helvetica; color: rgb(0, 0, 0); "></span></div></body></html>