Apollo 12 Magnetometer: Measurement of a Steady Magnetic Field on the Surface of the Moon

Dyal, P.; Parkin, C. W.; Sonett, C. P.

doi:10.1126/science.169.3947.762

Cited by 85 publications

(38 citation statements)

References 10 publications

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“…The Apollo missions shortly after, however, did detect small areas of weak crustal magnetic fields (Dyal et al 1970(Dyal et al , 1974Sharp et al 1973;Fuller 1974;Russell et al 1974). Recent high-resolution measurements characterized these LMAs to have size up to several hundred kilometers with surface magnetic field strengths ranging from 0.1 up to 1000 nT (Lin et al 1998;Mitchell et al 2008;Purucker 2008;Richmond & Hood 2008;Purucker & Nicholas 2010).…”

Section: Lunar Magnetic Anomalymentioning

confidence: 99%

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

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We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind,and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their crosssections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

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Section: Lunar Magnetic Anomalymentioning

confidence: 99%

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

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“…It does, however, have several small, static regions of low magnetic field ( -nT 50 500 ) on the surface (Dyal et al 1970;Coleman et al 1972). The distribution of these magnetic field anomalies on the Moon varies from thousands of kilometers across, irregular conglomerations and clusters, to relatively small (hundreds of kilometers across) and isolated featuressuch as the Reiner Gamma formation and Gerasimovich magnetic anomaly (Hood & Schubert 1980;Halekas et al 2001;Richmond et al 2003;Hood & Artemieva 2008).…”

Section: Introductionmentioning

confidence: 99%

3d Pic Simulations of Collisionless Shocks at Lunar Magnetic Anomalies and Their Role in Forming Lunar Swirls

Bamford

Alves

Cruz

et al. 2016

ApJ

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Investigation of the lunar crustal magnetic anomalies offers a comprehensive long-term data set of observations of small-scale magnetic fields and their interaction with the solar wind. In this paper a review of the observations of lunar mini-magnetospheres is compared quantifiably with theoretical kinetic-scale plasma physics and 3D particlein-cell simulations. The aim of this paper is to provide a complete picture of all the aspects of the phenomena and to show how the observations from all the different and international missions interrelate. The analysis shows that the simulations are consistent with the formation of miniature (smaller than the ion Larmor orbit) collisionless shocks and miniature magnetospheric cavities, which has not been demonstrated previously. The simulations reproduce the finesse and form of the differential proton patterns that are believed to be responsible for the creation of both the "lunar swirls" and "dark lanes." Using a mature plasma physics code like OSIRIS allows us, for the first time, to make a side-by-side comparison between model and space observations. This is shown for all of the key plasma parameters observed to date by spacecraft, including the spectral imaging data of the lunar swirls. The analysis of miniature magnetic structures offers insight into multi-scale mechanisms and kinetic-scale aspects of planetary magnetospheres.

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“…(Some of the interpretation of the early evidence for the presence of magnetised material in the samples was controversial, see Fuller 1974. ) However, direct evidence of the magnitude of the surface field was obtained through the use of the first lunar surface magnetometer delivered by Apollo 12 (Dyal et al 1970a). Using similar surface magnetometers on subsequent Apollo missions described by Dyal et al (1974) around the landing sites provided data that confirmed the existence of crustal magnetism.…”

Section: The Moonmentioning

confidence: 96%

“…The measurements start on 8 December 1969 at 13:38 UT. The large amplitude angular discontinuity at Explorer 35 at about 5 minutes after the start of the measurements caused a variation in the field measured by the LSM that is superposed on the steady ∼38 nT crustal field background (from Dyal et al 1972a) altitude of 100 km for a 10-months long operational phase, followed by a mission extension that came to an end on 11 June 2009 when the spacecraft was deorbited to impact the Moon. Kaguya carried a magnetometer that had been very carefully calibrated , and a long, 12-m magnetometer boom that was successfully deployed after launch.…”

Section: The Moonmentioning

confidence: 99%

Planetary Magnetic Field Measurements: Missions and Instrumentation

Balogh

2010

Space Sci Rev

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The nature and diversity of the magnetic properties of the planets have been investigated by a large number of space missions over the past 50 years. It is clear that without the magnetic field measurements that have been carried out in the vicinity of all the planets, the state of their interior and their evolution since their formation would not be understood even though questions remain about how the different planetary dynamos (in six of the eight planets) work. This paper describes the motivation for making magnetic field measurements, the instrumentation that has been used and many of the missions that carried out the pioneering observations. Emphasis is given to the historically important early missions even if the results from these have been in some cases bettered by later missions.Keywords Planetary magnetism · Planetary space missions · Space magnetometers Motivation for Measuring the Magnetic Field of Planets and SatellitesThe presence or absence of a planetary scale magnetic field places a strong constraint of the state of a planet's interior. The nature of the field (dipolar, multipolar, crustal, induced or, in general, the combination of all such terms in different proportions) provides further indication of the details of the thermal evolution and current state and has been used extensively in constraining models of planetary structure. If a planet's magnetic field is dominated by dipolar and low-order multipolar terms, the presumed existence of a magnetohydrodynamic dynamo in the planet's interior is an additional, important factor in its internal dynamics.For planets in the solar system, the interaction of the planetary obstacle with the allpervasive solar wind critically influences the magnetic environment of planets. The interaction depends strongly on the nature of the magnetism of the planetary body, as well as on

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Apollo 12 Magnetometer: Measurement of a Steady Magnetic Field on the Surface of the Moon

Cited by 85 publications

References 10 publications

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Magnetic Null Points in Kinetic Simulations of Space Plasmas

3d Pic Simulations of Collisionless Shocks at Lunar Magnetic Anomalies and Their Role in Forming Lunar Swirls

Planetary Magnetic Field Measurements: Missions and Instrumentation

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