Initial mapping and interpretation of lunar crustal magnetic anomalies using Lunar Prospector magnetometer data

Hood, L. L.; Zakharian, Aramais R.; Halekas, J. S.; Mitchell, D. L.; Lin, R. P.; Acuña, M. H.; Binder, A. B.

doi:10.1029/2000je001366

Cited by 197 publications

(198 citation statements)

References 25 publications

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“…Relatively weak fields (up to some tens of nT at spacecraft altitude) were mostly recorded antipodal to the largest lunar basins (Imbrium, Crisium, Serenitatis) (Anderson and Wilhelms 1979). This suggests that these magnetic anomalies are caused by the ejecta of impact processes, that were deposited at antipodal locations in the presence of an impact-amplified magnetic field (Hood et al 2001). …”

Section: The Moonmentioning

confidence: 98%

“…Paleointensity measurements on the returned samples suggest that the lunar surface field was comparable in intensity to the present-day terrestrial surface field about 3.6 to 3.8 Gy ago. Recent measurements by Lunar Prospector refined our understanding of the lunar magnetic field (Hood et al 2001). Relatively weak fields (up to some tens of nT at spacecraft altitude) were mostly recorded antipodal to the largest lunar basins (Imbrium, Crisium, Serenitatis) (Anderson and Wilhelms 1979).…”

Section: The Moonmentioning

confidence: 99%

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The Origin of Mercury’s Internal Magnetic Field

et al. 2007

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Mariner 10 measurements proved the existence of a large-scale internal magnetic field on Mercury. The observed field amplitude, however, is too weak to be compatible with typical convective planetary dynamos. The Lorentz force based on an extrapolation of Mariner 10 data to the dynamo region is 10 −4 times smaller than the Coriolis force. This is at odds with the idea that planetary dynamos are thought to work in the so-called magnetostrophic regime, where Coriolis force and Lorentz force should be of comparable magnitude. Recent convective dynamo simulations reviewed here seem to resolve this caveat. We show that the available convective power indeed suffices to drive a magnetostrophic dynamo even when the heat flow though Mercury's core-mantle boundary is subadiabatic, as suggested by thermal evolution models. Two possible causes are analyzed that could explain why the observations do not reflect a stronger internal field. First, toroidal magnetic fields can be strong but are confined to the conductive core, and second, the observations do not resolve potentially strong small-scale contributions. We review different dynamo simulations that promote either or both effects by (1) strongly driving convection, (2) assuming a particularly small inner core, or (3) assuming a very large inner core. These models still fall somewhat short of explaining the low amplitude of Mariner 10 observations, but the incorporation of an additional effect helps to reach this goal: The subadiabatic heat flow through Mercury's core-mantle boundary may cause the outer part of the core to be stably stratified, which would largely exclude convective motions in this region. The magnetic field, which is small scale, strong, and very time dependent in the lower convective part of the core, must diffuse through the stagnant layer. Here, the electromagnetic skin effect filters out the more rapidly varying high-order contributions and mainly leaves behind the weaker and slower varying dipole and quadrupole components (Christensen in Nature 444: [1056][1057][1058] 2006). Messenger and BepiColombo data will allow us to discriminate between the various models in terms of the magnetic fields spatial structure, its degree of axisymmetry, and its secular variation.

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Section: The Moonmentioning

confidence: 98%

Section: The Moonmentioning

confidence: 99%

The Origin of Mercury’s Internal Magnetic Field

et al. 2007

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“…A previous study 28) suggested that the most probable sources of the ancient lunar magnetic fields were (1) a former core dynamo during a high-field epoch and (2) transient magnetic fields generated by the interaction of impact plasmas with the ambient field during brief periods of ejecta emplacement. Distribution of magnetic anomalies less than 1 nT were definitely confirmed in the Crisium-, the Serenitatis-, and the Imbrium-antipodes in the SPA basin and in the Lemonosov-Fleming, the Crisium, the Moscoviense, the Apollo basins, isolated anomalies such as the Reiner Gamma, and newly identified eleven isolated anomalies from the 100 km altitude orbit 29) .…”

Section: Origin Of the Lunar Magnetic Fieldmentioning

confidence: 99%

Science Summary of Kaguya Mission

Kato

Sasaki

Takizawa

2012

AEROSPACE TECHNOLOGY JAPAN

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“…A previous study has indicated that the most probable sources of the ancient lunar magnetic fields were (1) a former core dynamo during a high-field epoch and (2) transient magnetic fields generated by the interaction of impact plasmas with the ambient field during brief periods of ejecta emplacement 8) . The LMAG Kaguya mission aims at finding weak magnetic remnants less than 10 -5 T using an electron reflectometer.…”

Section: Origin Of Lunar Magnetic Fieldmentioning

confidence: 99%

Science Objectives and Initial Operations of SELENE (Kaguya) Mission

Kato

Sobue

Sasaki

et al. 2009

Trans. JSASS Space Tech. Japan

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The Japanese lunar mission SELENE (Kaguya) was successfully launched by the H2A No.13 rocket on September 14, 2007. After being inserted into a nominal orbit at an altitude of 100 km for remote sensing on October 19, 2007, a sounder antenna, magnetometer boom, and plasmasphere cameras were deployed before the testing of scientific instruments. Acquisition of scienctific data was carried out for ten months after the nominal mission period that began from the middle of December, 2007. Scientific objectives and perspectives along with the status of the initial operations of Kaguya are described in this paper.

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Initial mapping and interpretation of lunar crustal magnetic anomalies using Lunar Prospector magnetometer data

Cited by 197 publications

References 25 publications

The Origin of Mercury’s Internal Magnetic Field

The Origin of Mercury’s Internal Magnetic Field

Science Summary of Kaguya Mission

Science Objectives and Initial Operations of SELENE (Kaguya) Mission

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