image: In this perspective view, we look west across a linear scarp that separates two terrains, higher topography to the right (mostly red and yellow colors) and lower topography to the left (mostly blue colors). The scarp is a tectonic feature formed by low-angle faults thrusting the now-higher topography over the area of lower topography, and is the location of one of the crustal magnetic signals. The scarp is about 30 km wide and several hundred kilometers long and the largest crater near the center of the image (superposed on the scarp) is about 30 km in diameter. The background image is Mercury Dual Imaging System global mosaic, colored by surface elevation measured by the Mercury Laser Altimeter, both draped over a digital elevation model derived from MLA data. view more
Credit: C redit: NASA/Johns Hopkins University Applied Physics Laboratory/Car negie Institution of Washington
This news release is available in Japanese.
The Messenger spacecraft, which crash-landed into Mercury just a few days ago, found traces of magnetization in Mercury's crust, a new study reports. The presence of residual magnetization provides insights into the planet's evolution. It suggests that a dynamo, driven by the electrically conductive molten iron at Mercury's core, generated a magnetic field 3.8 billion years ago. As Mercury also has a magnetic field in operation today, the evidence for an ancient field suggests that Mercury's dynamo has persisted for billions of years. On April 30, 2015, the Messenger spacecraft - the first to orbit Mercury - crashed into the enigmatic planet. Launched in 2004, Messenger had been in space for more than a decade. During the four years it orbited Mercury, Messenger provided vast amounts of data to scientists. Now, using low-altitude satellite observations from the spacecraft, Catherine Johnson et al. report a weak magnetization signal that appears to emanate from an ancient region of Mercury's crust. The finding that Mercury's core dynamo field was present early in the planet's history provides important insight into the evolution of the planet's core and the dynamo action within it.
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Article #24: "Low-altitude Magnetic Field Measurements by MESSENGER Reveal Mercury's Ancient Crustal Field," by C.L. Johnson; L.C. Philpott at University of British Columbia in Vancouver, BC, Canada; C.L. Johnson; M.A. Siegler at Planetary Science Institute in Tucson, AZ; R.J. Phillips at Southwest Research Institute in Boulder, CO M.E. Purucker; E. Mazarico; G.A. Neumann at NASA Goddard Space Flight Center in Greenbelt, MD; B.J. Anderson; B.W. Denevi; H. Korth at Johns Hopkins University in Laurel, MD; P.K. Byrne at Lunar and Planetary Institute in Houston, TX; J.M. Feinberg at University of Minnesota in Minneapolis, MN; S.A. Hauck II at Case Western Reserve University in Cleveland, OH; J.W. Head III at Brown University in Providence, RI; P.B. James; S.C. Solomon at Columbia University in Palisades, NY; M.A. Siegler at Southern Methodist University in Dallas, TX; N.A. Tsyganenko at Saint Petersburg State University in Saint Petersburg, Russia; P.K. Byrne; S.C. Solomon at Carnegie Institution of Washington in Washington, DC.
Journal
Science