Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

Autor: Johnson CL; Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada. Planetary Science Institute, Tucson, AZ 85719, USA. cjohnson@eos.ubc.ca., Phillips RJ; Planetary Science Directorate, Southwest Research Institute, Boulder, CO 80302, USA., Purucker ME; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA., Anderson BJ; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA., Byrne PK; Lunar and Planetary Institute, Houston, TX 77058, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA., Denevi BW; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA., Feinberg JM; Institute for Rock Magnetism, Department of Earth Sciences, University of Minnesota, Minneapolis, MN, 55455, USA., Hauck SA 2nd; Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA., Head JW 3rd; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA., Korth H; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA., James PB; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA., Mazarico E; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA., Neumann GA; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA., Philpott LC; Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada., Siegler MA; Planetary Science Institute, Tucson, AZ 85719, USA. Department of Earth Sciences, Southern Methodist University, Dallas, TX 75205, USA., Tsyganenko NA; Institute and Faculty of Physics, Saint Petersburg State University, Saint Petersburg, Russia., Solomon SC; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.
Jazyk: angličtina
Zdroj: Science (New York, N.Y.) [Science] 2015 May 22; Vol. 348 (6237), pp. 892-5. Date of Electronic Publication: 2015 May 07.
DOI: 10.1126/science.aaa8720
Abstrakt: Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.
(Copyright © 2015, American Association for the Advancement of Science.)
Databáze: MEDLINE
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