Chemistry of impact events on the Moon

Berezhnoy, A. A.

doi:10.1016/j.icarus.2013.05.030

Cited by 26 publications

(14 citation statements)

References 63 publications

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“…Ca-bearing molecules in impact vapor plumes are more likely to be produced than Ca atoms [Berezhnoy and Klumov, 2008]. These molecules get dissociated quickly [Berezhnoy and Klumov, 2008;Berezhnoy, 2013] releasing energetic Ca atoms [Burger et al, 2014;Christou et al, 2015;Killen, 2016;Killen et al, 2005]. Such a scenario would be consistent with recent observations and models of micrometeoroids at Earth showing that there is a strong dawn enhancement in the impactor flux [Janches et al, 2006;Pifko et al, 2013].…”

Section: Introduction and Motivation For The Current Worksupporting

confidence: 72%

Investigation of the possible effects of comet Encke's meteoroid stream on the Ca exosphere of Mercury

et al. 2017

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The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) observations of the seasonal variability of Mercury's Ca exosphere are consistent with the general idea that the Ca atoms originate from the bombardment of the surface by particles from comet 2P/Encke. The generating mechanism is believed to be a combination of different processes including the release of atomic and molecular surface particles and the photodissociation of exospheric molecules. Considering different generation and loss mechanisms, we perform simulations with a 3‐D Monte Carlo model based on the exosphere generation model by Mura et al. (2009). We present for the first time the 3‐D spatial distribution of the CaO and Ca exospheres generated through the process of micrometeoroid impact vaporization, and we show that the morphology of the latter is consistent with the available MESSENGER/Mercury Atmospheric and Surface Composition Spectrometer observations. The results presented in this paper can be useful in the exosphere observations planning for BepiColombo, the upcoming European Space Agency‐Japanese Aerospace Exploration Agency mission to Mercury.

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Section: Introduction and Motivation For The Current Worksupporting

confidence: 72%

Investigation of the possible effects of comet Encke's meteoroid stream on the Ca exosphere of Mercury

et al. 2017

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“…Using a similar model calibration to that used here, Pokorný et al () found that the amount of predicted impact vaporization flux on Mercury's surface is two orders of magnitude larger for species such as Mg than the estimated values derived from the MErcury Surface, Space ENvironment, GEochemstry, and Ranging (MESSENGER) spacecraft observations (Merkel et al, ). In order to find agreement between the dynamical meteoroid model and the observations, the authors suggested that the impact vaporization relation (equation ) may overestimate the contribution of higher impact velocities V imp > 20 km/s to the total vapor because of losses to other phases (Berezhnoy, ). If that is the case, both the total impact vaporization rates and the LT dependence of the impact‐derived exosphere will be different.…”

Section: Meteoroid Impact Effects On the Lunar Surfacementioning

confidence: 99%

Meteoroids at the Moon: Orbital Properties, Surface Vaporization, and Impact Ejecta Production

et al. 2019

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We use a dynamical model to characterize the monthly and yearly variations of the lunar meteoroid environment for meteoroids originating from short and long‐period comets and the main‐belt asteroids. Our results show that if we assume the meteoroid mass flux of 43.3 tons per day at Earth, inferred from previous works, the mass flux of meteoroids impacting the Moon is 30 times smaller, approximately 1.4 tons per day, and shows variations of the order of 10% over a year. The mass flux difference is due to the combined effect of the smaller cross‐section of the Moon (factor of 13.46) and Earth's larger gravitational focusing (factor of 2–2.5). The lunar surface is vaporized by these impactors at an average impact vaporization flux of 11.6 × 10−16 g·cm−2·s−1, providing a significant source for the rarefied lunar exosphere. Our model predicts acceptable vaporization rates and reproduces the local time dependence of observations of the dust ejecta cloud, measured by the Lunar Dust Experiment on board NASA's Lunar Atmosphere and Dust Environment (LADEE) satellite. However, the predicted density of the lunar ejecta cloud is four orders of magnitude larger than reported values by LADEE. This discrepancy might be attributed to a much lower yield from meteoroid impacts on fluffy lunar regolith and/or a lower detection efficiency of the LADEE dust detector. We suggest an upper limit of 30 cm per million years for the soil gardening rate from small meteoroids.

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“…Comprehensive reviews of photodissociation cross sections of molecules of astrophysical interest have been published (Huebner et al 1992;Huebner & Mukherjee 2015;Heays et al 2017). Simple molecules can be delivered to the exospheres of Mercury and the Moon during meteoroid bombardment (Berezhnoy & Klumov 2008;Berezhnoy 2013). Volcanic eruptions are main sources of chlorides and fluorides of alkali elements in the atmosphere of Io (Schaefer & Fegley 2005).…”

Section: Introductionmentioning

confidence: 99%

Photolysis of diatomic molecules as a source of atoms in planetary exospheres

Valiev

Berezhnoy

Гриценко

et al. 2020

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We calculated the cross sections of photolysis of OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF molecules using quantum chemistry methods. The maximal values for photolysis cross sections of alkali metal monoxides are on the order of 10−18 cm2. The lifetimes of photolysis for quiet Sun at 1 astronomical unit are estimated as 2.0 × 105, 28, 5, 14, 2.1 × 105, 225, 42, 52, 2 × 106, 35 400, 486, and 30 400 s for OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF, respectively. We performed a comparison between values of photolysis lifetimes obtained in this work and in previous studies. Based on such a comparison, our estimations of photolysis lifetimes of OH, HCl, and HF have an accuracy of about a factor of 2. We determined typical kinetic energies of main peaks of photolysis-generated metal atoms. Impact-produced LiO, NaO, KO, NaCl, and KCl molecules are destroyed in the lunar and Hermean exospheres almost completely during the first ballistic flight, while other considered molecules are more stable against destruction by photolysis.

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Chemistry of impact events on the Moon

Cited by 26 publications

References 63 publications

Investigation of the possible effects of comet Encke's meteoroid stream on the Ca exosphere of Mercury

Investigation of the possible effects of comet Encke's meteoroid stream on the Ca exosphere of Mercury

Meteoroids at the Moon: Orbital Properties, Surface Vaporization, and Impact Ejecta Production

Photolysis of diatomic molecules as a source of atoms in planetary exospheres

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