Observations of Moon‐plasma interactions by orbital and surface experiments

Schubert, G.; Lichtenstein, B. R.

doi:10.1029/rg012i004p00592

Cited by 81 publications

(20 citation statements)

References 110 publications

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“…As Schubert and Lichtenstein [1974] have very cogently argued, it is difficult to define a Mach cone with respect to the undisturbed solar wind because of the presence of the limb shocks. The only true Mach cone with respect to the undisturbed solar wind must lie outside of these compressional features.…”

Section: Resultsmentioning

confidence: 99%

“…The Explorer 35 spacecraft and the Apollo 15 and 16 subsatellites [ Ness , 1972; Schubert and Lichtenstein , 1974, and references therein] provided the first observations of the lunar plasma wake. Explorer 35 surveyed the wake at distances of 1000–10,000 km from the surface of the Moon, while the Apollo subsatellites provided limited coverage in a region ∼100–160 km above the lunar surface.…”

Section: Introductionmentioning

confidence: 99%

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Electrons and magnetic fields in the lunar plasma wake

Halekas¹

2005

J. Geophys. Res.

141

155

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[1] Earth's Moon, lacking both a global magnetic field and any significant atmosphere, presents an ideal location to study plasma flow past a solar system body in one of its simplest incarnations. Despite its relative simplicity, however, the lunar wake interaction displays a rich array of physics, with both fluid and kinetic aspects. We present a new study of the lunar wake, using measurements from Lunar Prospector (LP) to determine the magnetic field, electron density and temperature, and electrostatic potential. We use these data and Wind key parameter data to characterize the wake near the Moon. At 85-115 km above the Moon we observe a ''classical'' wake signature, with enhanced magnetic fields in the central wake and reduced fields near the boundary. The magnetic signature at these altitudes responds clearly to changes in solar wind parameters, while that at 20-45 km depends mainly on crustal fields. We also observe an ambipolar potential drop across the wake boundary (resulting in central wake potentials of about À300 V relative to the solar wind) and greatly reduced electron density and increased electron temperature in the wake. The wake morphology, in terms of both electron parameters and magnetic fields, is well described by self-similar solutions for plasma expansion into a void and the resulting diamagnetic current system, but only if Kappa functions are used to describe the solar wind electron distributions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrons and magnetic fields in the lunar plasma wake

Halekas¹

2005

J. Geophys. Res.

141

155

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“…The interaction between the Moon and solar wind has been studied since the 1960s (see the review by Schubert and Lichtenstein [1974], and references therein).…”

Section: Introductionmentioning

confidence: 99%

Moon‐related nonthermal ions observed by Nozomi: Species, sources, and generation mechanisms

Futaana¹

2003

J. Geophys. Res.

245

102

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The 3‐D velocity distribution functions of nonthermal ions observed in the vicinity of the Moon have been analyzed to understand the interaction between the solar wind and the Moon. The observation was made during the lunar swing‐by of the Nozomi spacecraft, and the closest approach was about 1.6 RL from the Moon's surface. Both Nozomi and the Moon were located in the solar wind, and nonthermal ions were observed only when the spacecraft was very close to the Moon. The nonthermal ions were measured by a Particle Spectrum Analyzer/Ion Spectrum Analyzer (PSA/ISA) on board the Nozomi. After analyses and careful examination of the 3‐D velocity distribution of the nonthermal ions, the characteristics of the nonthermal ions were revealed as follows: The nonthermal ions have a partial ring structure in the phase space, they are protons, their source location is the dayside of the Moon, and they have large velocities when they are generated. We propose the following scenario of a solar wind interaction with the Moon: The electromagnetic field in the vicinity of the Moon must have a dynamic structure, possibly a miniature bow shock associated with a local magnetic anomaly, where some of the solar wind protons are deflected violating their first adiabatic invariant. After the deflection, they move under the force of the convection electric field and gyrate around the magnetic field in the solar wind. This motion forms a partial ring structure with large initial velocities in the velocity phase space.

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“…Ness et al 1968;Schubert and Lichtenstein 1974). Figure 2 is a schematic picture of the plasma environment around the moon when the moon is located in the solar wind.…”

Section: Science On the Plasma Waves And Plasma Physics On The Moonmentioning

confidence: 98%

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

et al. 2010

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The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural 146 T. Ono et al. radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.

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Observations of Moon‐plasma interactions by orbital and surface experiments

Cited by 81 publications

References 110 publications

Electrons and magnetic fields in the lunar plasma wake

Electrons and magnetic fields in the lunar plasma wake

Moon‐related nonthermal ions observed by Nozomi: Species, sources, and generation mechanisms

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

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