Magnetism and the Interior of the Moon

Dyal, P.; Parkin, C. W.; Daily, William

doi:10.1002/9781118782118.ch6

Cited by 16 publications

(21 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the case of the Moon, the lunar magnetic field has been studied indirectly via the natural remanent magnetization of the returned lunar samples and directly with magnetometers carried to the surface and placed in orbit at low altitude above the surface on the Apollo 15 and Apollo 16 subsatellites (see reviews in Dyal et al, 1974;Fuller and Cisowski, 1987). Thus, knowledge about the magnetic field evolution can be used to constrain the thermal evolution of a planet.…”

Section: Magnetic Field Generationmentioning

confidence: 99%

Dynamics and Thermal History of the Terrestrial Planets, the Moon, and Io

Breuer

Moore

2015

Treatise on Geophysics

View full text Add to dashboard Cite

Section: Magnetic Field Generationmentioning

confidence: 99%

Dynamics and Thermal History of the Terrestrial Planets, the Moon, and Io

Breuer

Moore

2015

Treatise on Geophysics

View full text Add to dashboard Cite

“…Lunar crustal fields are extensively spread over the entire lunar surface with various field intensities, but they are mostly clustered on the southern hemisphere of the lunar far side [ Richmond and Hood , ; Mitchell et al , ; Tsunakawa et al , ]. The maximum strength of these fields on the lunar surface is expected to be at least a few hundred nT [ Dyal et al , ; Hood et al , ; Mitchell et al , ].…”

Section: Introductionmentioning

confidence: 99%

Solar wind plasma interaction with Gerasimovich lunar magnetic anomaly

et al. 2015

View full text Add to dashboard Cite

We present the results of the first local hybrid simulations (particle ions and fluid electrons) for the solar wind plasma interaction with realistic lunar crustal fields. We use a three‐dimensional hybrid model of plasma and an empirical model of the Gerasimovich magnetic anomaly based on Lunar Prospector observations. We examine the effects of low and high solar wind dynamic pressures on this interaction when the Gerasimovich magnetic anomaly is located at nearly 20∘ solar zenith angle. We find that for low solar wind dynamic pressure, the crustal fields mostly deflect the solar wind plasma, form a plasma void at very close distances to the Moon (below 20 km above the surface), and reflect nearly 5% of the solar wind in charged form. In contrast, during high solar wind dynamic pressure, the crustal fields are more compressed, the solar wind is less deflected, and the lunar surface is less shielded from impinging solar wind flux, but the solar wind ion reflection is more locally intensified (up to 25%) compared to low dynamic pressures. The difference is associated with an electrostatic potential that forms over the Gerasimovich magnetic anomaly as well as the effects of solar wind plasma on the crustal fields during low and high dynamic pressures. Finally, we show that an antimoonward Hall electric field is the dominant electric field for ∼3 km altitude and higher, and an ambipolar electric field has a noticeable contribution to the electric field at close distances (<3 km) to the Moon.

show abstract

“…While our Moon does not possess a large global‐scale magnetic field such as that of the Earth, Mercury, and the gas giant planets, it does have localized magnetic fields near its surface due to permanent magnetization in its upper crust [e.g., Hood , ]. These magnetic concentrations, or magcons, have field strengths that are considerably larger than the average interplanetary magnetic field at 1 AU [ Dyal et al , ; Halekas et al , ; Hood et al , ; Mitchell et al , ]. It has been known for some time that magcons may present a barrier to the penetration of solar wind in the lunar regolith [ Hood and Schubert , ].…”

Section: Introductionmentioning

confidence: 99%

Hybrid simulation of the interaction of solar wind protons with a concentrated lunar magnetic anomaly

Giacalone

Hood

2015

JGR Space Physics

View full text Add to dashboard Cite

Using a two-dimensional hybrid simulation, we study the physics of the interaction of the solar wind with a localized magnetic field concentration, or "magcon," on the Moon. Our simulation treats the solar wind protons kinetically and the electrons as a charge-neutralizing fluid. This approach is necessary because the characteristic scale of the magcon is of the same order or smaller than the proton inertial length-the characteristic scale in the hybrid simulation. Specifically, we consider a case in which the incident solar wind flows exactly normal to the lunar surface, and the magcon is represented by a simple dipole whose moment is parallel to the surface, with a center just below it. We find that while the magcon causes the solar wind to be deflected and decelerated, it does not completely shield the lunar surface anywhere. However, protons which impact the surface in the center of the magnetic anomaly have energies well below the solar wind ram energy. Thus, in this region, any backscattered neutral particles resulting from the interaction of solar wind protons with the lunar regolith would have energies lower than that of the solar wind. Moreover, very few neutrals, if any, would emanate from within the magcon with energies comparable to the solar wind energy. This may explain recent observations of lunar energetic neutral atoms associated with a strong crustal magnetic anomaly. Our study also finds that a significant fraction of the incoming solar wind protons are reflected back into space before reaching the surface. These particles are reflected by a strong electrostatic field which results from the difference in the proton and electron inertia. The reflected particles are seen at very high altitudes above the Moon, over 200 km, and over a much broader spatial scale than the magcon, several hundred kilometers at least. Our simulation also revealed a second population of reflected particles which originate from the side of the magcon where the interplanetary and magcon magnetic fields are directed opposite to one another, leading to a magnetic topology much like magnetic reconnection. As previously reflected particles move through this region, they are deflected upward, away from the surface, forming a second component. Our simulation has a number of similarities to recent in situ spacecraft observations of reflected ions above and around magcons.

show abstract

Magnetism and the Interior of the Moon

Cited by 16 publications

References 76 publications

Dynamics and Thermal History of the Terrestrial Planets, the Moon, and Io

Dynamics and Thermal History of the Terrestrial Planets, the Moon, and Io

Solar wind plasma interaction with Gerasimovich lunar magnetic anomaly

Hybrid simulation of the interaction of solar wind protons with a concentrated lunar magnetic anomaly

Contact Info

Product

Resources

About