Electrical conductivity anomaly beneath mare serenitatis detected by Lunokhod 2 and Apollo 16 magnetometers

Vanyan, L. L.; Vnuchkova, T. A.; Egorov, I. V.; Basilevsky, A. T.; Eroshenko, E. A.; Fainberg, E. B.; Dyal, P.; Daily, William

doi:10.1007/bf00897087

Cited by 12 publications

(8 citation statements)

References 4 publications

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“…A similar tendency towards linear polarization was discovered at the eastern boundary of Mare Serenitatis by analyses of magnetic fluctuations in the period band 5-150 sec simultaneously observed by Lunokhod 2 and Apollo 16 (Figure 8) during January-March of 1973 (Vanyan et al, 1979). These are two mathematical models to explain the observed anisotropy.…”

Section: Regional Anomalies Of Lunar Conductivitysupporting

confidence: 64%

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The electrical conductivity of the Moon

Vanyan

1980

Geophysical Surveys

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Abslxact. Investigations of the lunar electrical conductivity were described in excellent reviews by Sonett (1974) and Dyal et al. (1976). In this paper we will try to consider some new aspects of this problem in comparison with the Earth's data. Basic PrinciplesAs in the case of Earth induction, the EM-sounding of the Moon is based on Faraday's law. The main role in lunar excitation belongs to the TE-mode while the contribution of the TM-mode can be neglected due to very high resistivity of the near-surface dry lunar layer.The Moon has neither a magnetosphere nor an ionosphere with current systems. The only sources of induction are electrical currents in interplanetary plasma, running past the Moon like plane waves. If the solar wind velocity is as great as 10 a km/sec and magnetic fluctuations have periods about 102 sec, the wavelength reaches l0 s kin, i.e. some order to magnitude greater than the lunar radius. In this case one can consider this plane wave as a spatially homogeneous time harmonic magnetic field. Such a field can be described by the first spherical harmonic. However, if the solar wind velocity is only 150 km/sec and the period of fluctuations decreases to 10 sec, the wave lengths become shorter than the radius of the Moon. This corresponds approximately to the sixth-order spherical harmonic.Note, that the greater the harmonic number, the smaller the thickness of the layer which we can investigate. The greatest depth (not more than half a radius) can be investigated by using the first harmonic. Therefore one must try to use actually the first harmonic for lunar sounding. Unfortunately there is an additional cause which provides high harmonics, namely, the asymmetry of the lunar environment. Asymmetric Model of Electromagnetic Induction in the MoonDuring each revolution around the Earth the Moon crosses three different regions ( Figure 1).(1) The Earth's magnetic tail, where very low plasma density is observed.(2) Solar wind where plasma flows in the antisolar direction with the frozen-in magnetic field.(3) The magnetosheath which is the outer shell of the magnetosphere. In this area

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Section: Regional Anomalies Of Lunar Conductivitysupporting

confidence: 64%

“…The interesting possibility of lunar sounding using two surface magnetometers with no satellite data has recently been described by Vanyan et al (1977).…”

Section: Technique Of the Magnetovariation Lunar Soundingmentioning

confidence: 99%

The electrical conductivity of the Moon

Vanyan

1980

Geophysical Surveys

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“…A start on the problem, including the background plasma, has been made by Hood and Schubert [1978] but is limited by both the lack of data which have been worked on in detail (except for those noted later) and the fundamental limitation imposed upon time series length by the restriction to segments of only about 2 days for each of the subneighborhoods of the tail; that is, the two lobes of the plasma sheet and the corresponding two lobes of the tail adjoining the sheet are bypassed. Other topics outside the scope of this review are the regional anisotropies found at the Hadley and Serenitatis landing sites Schubert et al, 1974a;Dolginov et al, 1976;Vanyan et al, 1979] and the interaction of the solar wind with the local and regional fields on the lunar surface [Dyal et al, 1972b]. In particular, the latter is probably associated with the creation of a background magnetohydrodynamic noise continuum whose importance for lunar induction is still debated.…”

Section: Relation To Electromagnetic Scatteringmentioning

confidence: 99%

Electromagnetic induction in the Moon

Sonett¹

1982

Reviews of Geophysics

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Except for a boundary layer of uncertain properties the moon constitutes a rigid (nonhydromagnetic) but electrically conducting target to the solar wind when unscreened by the earth's magnetosphere. At frequencies below 3 mHz, observed in the rest frame of the moon, fluctuations of the interplanetary and the geomagnetic tail fields excite eddy currents which penetrate deeper than half the lunar radius. At long wavelength (λ ≫ rM, where rM is the lunar radius) a time‐varying magnetic dipole is induced. Shorter wavelengths excite correspondingly higher‐order magnetic multipoles, but primarily in the outer parts of the moon because of skin depth limitations. The lunar response reaches a peak as frequency increases, diminishing with further increase in frequency. This is interpreted as evidence for the presence of the magnetic quadrupole moment. In the solar wind and magnetosheath the transverse electric mode in the moon is not accompanied by the corresponding transverse magnetic mode, since a bow shock wave is not detected. The latter is probably damped by the nonconducting lunar crust, though the moon is still polarized electrically. It is marginally possible that transient bow wave phenomena appear at times, but because of the high dynamic pressure of the solar wind and magnetosheath, most induced fields are confined to the lunar interior and perhaps the boundary layer. Furthermore, a theorem by Herbert et al. (1976) seems to preclude time‐variable induced magnetospheres. Magnetometer measurements of induction using Explorer and Apollo instruments are reviewed, from both the harmonic and the transient standpoint, and the resulting determination of internal bulk electrical conductivity is discussed. Estimates of both internal temperature and metallized core radius maxima are examined. The closeness of the estimated temperature to the Ringwood‐Essene solidus at 150‐ to 250‐km depth may be indicative of a layer of enhanced conductivity in lieu of high temperature. If so, this suggests a reduction in temperature, bringing the temperature into coincidence with other selenophysical parameters. A reduced core radius estimate with a one‐sigma upper limit of 360 km is reported. Application of inverse theory resolution tests has not been made pending completion of current work involving autoregressive models in attempting to isolate the angular spectrum of real or apparent incident wave normals, upon which the quadrupole response depends. This is also aimed at bypassing current limitations imposed by data gap convolution, data digitization noise, and noise thought to be generated by the interaction of the solar wind with local and regional permanent fields on the lunar surface. Because of length limitations, discussion of lunar electrodynamics has been restricted to the problem of induction, with accompanying subjects such as the flow field and regional electric fields on the moon mentioned only as required. A fuller treatment should include these matters. The review closes prior to ongoing work on high‐frequency induction ...

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“…The maria/highland boundary signifies several additional geophysical and mineralogical transitions: the change in albedo and UV/IR and UV/optical properties already mentionedwhich is tied to composition; an apparent correlation with rille structures corresponding to lava flows draining into mare basins, presumably (Whittaker 1972); and even changes in electrical conductivity properties presumably related to deep basalt concentrations and differing structure and cooling due to the ancient presence of lava (Vanyan et al 1979). The cooling of the maria and highlands were very different (Reindler & Arkani-Hamed 2001), which might lead to a situation in which mascons that tend to underlie the maria that were supported at early times might come to strain the surrounding material as the maria cool.…”

Section: Figure 2 As Well Asmentioning

confidence: 99%

Lunar Outgassing, Transient Phenomena, and the Return to the Moon. I. Existing Data

Crotts¹

2008

Astrophysical Journal

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In Paper I of this series, we show that transient lunar phenomena (TLPs) correlate with lunar outgassing, geographically, based on surface radon release episodes versus the visual record of telescopic observers (the later prone to major systematic biases of unspecified nature, which we were able to constrain in Paper I). In Paper II we calculate some of the basic predictions that this insight implies, in terms of outgassing/regolith interactions. In this paper we propose a path forward, in which current and forthcoming technology provide a more controlled and sensitive probe of lunar outgassing. Many of these techniques are currently being realized for the first time.Given the optical transient/outgassing connection, progress can be made by Earth-based remote sensing, and we suggest several programs of imaging, spectroscopy and combinations thereof. However, as found in Paper II, many aspects of lunar outgassing seem likely to be covert in nature. TLPs betray some outgassing, but not all outgassing produces TLPs. Some outgassing may never appear at the surface, but remain trapped in the regolith.As well as passive remote sensing, we also suggest more intrusive techniques, from radar mapping to in-situ probes. Understanding these volatiles seems promising in terms of their exploitation as a resource for human presence on the Moon and beyond, and offers an interesting scientific goal in its own right. This paper reads, therefore, as a series of proposed techniques, some in practice, some which might be soon, and some requiring significant future investment (some of which may prove unwise pending results from predecessor investigations). These point towards enhancement of our knowledge of lunar outgassing, its relation to other lunar processes, and an increase in our understanding of how volatiles are involved in the evolution of the Moon. We are compelled to emphasize certain ground-based observations in time for the flight of SELENE, LRO and other robotic missions, and others before extensive

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Electrical conductivity anomaly beneath mare serenitatis detected by Lunokhod 2 and Apollo 16 magnetometers

Cited by 12 publications

References 4 publications

The electrical conductivity of the Moon

The electrical conductivity of the Moon

Electromagnetic induction in the Moon

Lunar Outgassing, Transient Phenomena, and the Return to the Moon. I. Existing Data

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