<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><head></head><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="font: 12.0px Helvetica"></span><span style="letter-spacing: 0.0px">* <b>MESSENGER</b> - May 22, 2012</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px"><b>MESSENGER Measures Waves at the Boundary of Mercury's Magnetosphere</b></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">"MESSENGER scientists have concluded that waves driven by the Kelvin-Helmholtz (KH) instability play a key role in driving Mercury's magnetosphere. In a paper published recently in the Journal of Geophysical Research, the team reports on frequent detections of such waves at the outer edge of the innermost planet's magnetosphere.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">The paper was selected as an Editor's Highlight by the journal editor, and its findings are scheduled to be featured as a Research Highlight in Eos, the weekly newspaper of the American Geophysical Union.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">KH waves can develop at boundaries between two media in relative motion. "In principle, they are similar to the surface waves on water when there's a strong wind blowing," explains Torbjorn Sundberg, a postdoctoral fellow at NASA Goddard Space Flight Center and the lead author of the paper, entitled "MESSENGER orbital observations of large-amplitude Kelvin-Helmholtz waves at Mercury's magnetopause."</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">"You can, for example, sometimes see these waves develop on the upper edge of clouds, where they manifest as rolled-up vortices. Kelvin-Helmholtz waves can also be seen in Saturn's atmosphere, where they can develop at the boundary between the counter-streaming gas in the belts and the zones, the dark and bright bands seen across the planet," says Sundberg.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">In space plasmas, such waves are of interest because they can transfer mass and energy across the boundary between two otherwise separated regions. At Mercury, the boundary is between the relatively dense and fast-streaming solar wind and the more rarified magnetosphere."</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; color: rgb(31, 0, 172); "><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="text-decoration: underline ; letter-spacing: 0.0px">http://itunes.apple.com/us/app/messenger-nasas-mission-to/id510144229?ls=1&mt=8</span>.</a></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 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="font: 12.0px Courier; text-decoration: underline ; letter-spacing: 0.0px color: #3300ff">http://messenger.jhuapl.edu/</span></a>.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">* <b>Pack Your Backpack</b></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 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-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; color: rgb(51, 0, 255); "><span style="letter-spacing: 0.0px color: #000000">+ <a href="http://virtualfieldtrip.jpl.nasa.gov/"><span style="text-decoration: underline ; letter-spacing: 0.0px">http://virtualfieldtrip.jpl.nasa.gov/</span></a> </span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px">* Past, Present, Future and Proposed JPL Missions - <a href="http://www.jpl.nasa.gov/missions"><span style="font: 12.0px Courier; text-decoration: underline ; letter-spacing: 0.0px color: #3300ff">http://www.jpl.nasa.gov/missions</span></a>.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 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="font: 12.0px Courier; text-decoration: underline ; letter-spacing: 0.0px color: #3300ff">http://www2.jpl.nasa.gov/ambassador/index.html</span></a>.</span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; "><span style="letter-spacing: 0.0px"><b>Mars Missions</b></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"><b></b></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; text-align: center; font: normal normal normal 18px/normal Courier; color: rgb(31, 0, 172); "><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="font: 18.0px Courier; text-decoration: underline ; letter-spacing: 0.0px color: #1f00ac"><b><i></i></b></span></a></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px; "><span style="letter-spacing: 0.0px"><b></b></span><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Courier; color: rgb(51, 0, 255); "><span style="font: 12.0px Helvetica; color: #000000"></span></div></body></html>