The structure of Mercury's magnetic field from MESSENGER's first flyby.

Anderson, Brian J; Acuña, Mario H; Korth, Haje; Purucker, Michael E; Johnson, Catherine L; Slavin, James A; Solomon, Sean C; McNutt, Ralph L · Science · 2008

basic_science · Level V

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Abstract

During its first flyby of Mercury, the MESSENGER spacecraft measured the planet's near-equatorial magnetic field. The field strength is consistent to within an estimated uncertainty of 10% with that observed near the equator by Mariner 10. Centered dipole solutions yield a southward planetary moment of 230 to 290 nanotesla RM3 (where RM is Mercury's mean radius) tilted between 5 degrees and 12 degrees from the rotation axis. Multipole solutions yield non-dipolar contributions of 22% to 52% of the dipole field magnitude. Magnetopause and tail currents account for part of the high-order field, and plasma pressure effects may explain the remainder, so that a pure centered dipole cannot be ruled out.