The sodium and potassium atmosphere of the moon and its interaction with the surface

Sprague, A. L.; Kozlowski, R. W. H.; Hunten, D. M.; Wells, W. K.; Grosse, F.A.

doi:10.1016/0019-1035(92)90004-q

Cited by 93 publications

(77 citation statements)

References 26 publications

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“…The sodium distribution around the Moon, observed by mean wide-angle imaging (Flynn & Mendillo 1993) and the variation in the sodium emission with the altitude (Potter et al 2000) seems caused by the photon-stimulated desorption (PSD), which was proposed as the dominant source mechanism of this element in the lunar exosphere (Sprague et al 1992). Morgan et al (1988) suggested impact vaporization due to micrometeoroids as a source for the steady-state exosphere of the Moon.…”

Section: Introductionmentioning

confidence: 99%

Micrometeoroids flux on the Moon

Cremonese

Borin

Lucchetti

et al. 2013

A&A

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Context. The Moon has a tenuous exosphere consisting of atoms that are ejected from the surface by energetic processes, including hypervelocity micrometeoritic impacts, photon-stimulated desorption by UV radiation, and ion sputtering. Aims. We calculate the vapor and neutral Na production rates on the Moon caused by impacts of meteoroids in the radius range of 5−100 μm. We considered a previously published dynamical model to compute the flux of meteoroids at the heliocentric distance of the Moon. Methods. The orbital evolution of dust particles of different sizes is computed with an N-body numerical code. It includes the effects of Poynting-Robertson drag, solar wind drag, and planetary perturbations. The vapor production rate and the number of neutral atoms released in the exosphere of the Moon are computed with a well-established formulation. Results. The result shows that the neutral Na production rate computed following our model is higher than previous estimates. This difference can be due to the dynamical evolution model that we used to compute the flux and also to the mean velocity, which is 15.3 km s −1 instead of 12.75 km s −1 as reported in literature. Conclusions. Until now, the micrometeoritic impacts have been considered a negligible source for the release of neutral sodium atoms into the exosphere compared to other mechanisms, but according to our calculations, the contribution may be 8% of the photostimulated desorption at the subsolar point, becoming similar in the dawn and dusk regions and dominant on the night side.

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Section: Introductionmentioning

confidence: 99%

Micrometeoroids flux on the Moon

Cremonese

Borin

Lucchetti

et al. 2013

A&A

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“…where z gp = R m z/ (R m + z) is the geopotential height, H * = 300 km is the apparent scale height, and n 0 = 11 cm −3 is the surface number density of the Na atoms (Sprague et al, 1992). The model distribution of Na emission intensity was derived by integrating the number density of Na atoms along the line-of-sight within a distance smaller than 500 Moon radii, including the effects of the umbra and penumbra of the Moon.…”

Section: Resultsmentioning

confidence: 99%

“…A major breakthrough in the study of this exosphere occurred with the discovery of D-line emissions of sodium (Na) and potassium (K) from the ground (Potter and Morgan, 1988;Tyler et al, 1988). Optical remote sensing techniques enable us to investigate the source mechanism of Na atoms in terms of: (1) thermal desorption, (2) micrometeoroid impacts, (3) photodesorption by solar illumination, and (4) sputtering by solar-wind particles, including chemical reactions (see the review by Stern, 1999). These source mechanisms, which give a wide variety of release velocities and ejection rates acting in different surface regions, produce the characteristic distribution and dynamics of the lunar exosphere.…”

Section: Introductionmentioning

confidence: 99%

First optical observation of the Moon’s sodium exosphere from the lunar orbiter SELENE (Kaguya)

et al. 2009

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The first successful observations of resonant scattering emission from the lunar sodium exosphere were made from the lunar orbiter SELENE (Kaguya) using TVIS instruments during the period 17-19 December, 2008. The emission intensity of the NaD-line decreased by 12±6%, with an average value of 5.4 kR (kilorayleighs) in this period, which was preceded, by 1 day, by enhancement of the solar proton flux associated with a corotating interaction region. The results suggest that solar wind particles foster the diffusion of sodium atoms or ions in the lunar regolith up to the surface and that the time scale of the diffusion is a few tens of hours. The declining activity of the Geminid meteor shower is also one possible explanation for the decreasing sodium exosphere.

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“…Note that the decrease in the ESD cross section from Li + to Cs + (Ageev et al, 1995) suggests that the K + cross section is possibly smaller than that of Na + . The surface number density ratio of Na/K (∼2.9) was derived from the observations of Sprague et al (1992). The PSD yield of K + was thus taken to be 1.2 × 10 3 /cm 2 sec.…”

Section: Desorption Processesmentioning

confidence: 99%

“…They also indicated a strong dependence of vertical column abundance on zenith angle, which was fitted to a cosine-squared curve. Based on the observational results, we calculated the number density n i (h, φ) of the alkali atmosphere i at an altitude z and a zenith angle φ by using the geopotential altitude z gp (Sprague et al, 1992). n i (h, φ) is given by…”

Section: Ionization Of the Lunar Alkali Exospherementioning

confidence: 99%

Estimation of picked-up lunar ions for future compositional remote SIMS analyses of the lunar surface

Yokota

Saito

2005

Earth Planet Sp

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In situ measurement of Moon-originating ions picked-up in orbit round the Moon is expected to provide valuable information regarding the thin lunar atmosphere and surface. Secondary ions sputtered by the solar wind ions reflect the surface abundance. Global composition mapping of the lunar surface may be thus achieved by measuring the sputtered ions as one would perform laboratory SIMS. We studied the dynamics of picked-up lunar ions when the Moon was exposed to the solar wind. Our model's source mechanism involved photoionization of the lunar exospheric atoms, photon-stimulated ion desorption, and ion sputtering. We propose that an intense flux of picked-up lunar ions (10 4 /cm 2 sec) exists at an altitude of 100 km, for nearly a quarter of the orbit. The ion flux originating from the lunar surface is mono-directional and mono-energetic, and is distinguishable from that of lunar atmospheric origin whose energy spectra correspond to their spatial distribution. Our calculation suggested that ion measurements in orbit round the Moon enable remote SIMS analyses.

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The sodium and potassium atmosphere of the moon and its interaction with the surface

Cited by 93 publications

References 26 publications

Micrometeoroids flux on the Moon

Micrometeoroids flux on the Moon

First optical observation of the Moon’s sodium exosphere from the lunar orbiter SELENE (Kaguya)

Estimation of picked-up lunar ions for future compositional remote SIMS analyses of the lunar surface

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