![]() ![]() Enigma simulator online code#The ballistic part of the code includes the perturbative effects of the gravitational potentials of the earth and sun, resonant scatter of solar photons, charge exchange reactions with solar wind and terrestrial magnetosphere ions, photo-ionization, photo-dissociation, and escape. Enigma simulator online free#The basic task performed by LExS is to track a free atom or molecule through a sequence of random ballistic trajectories and intervening encounters with the lunar surface. Briefly, LExS can be thought of as a generalized subroutine that can be incorporated into a Monte Carlo program that, in turn, collects statistical data on the behavior of any neutral atomic or molecular species in the lunar exosphere. ![]() The code, which will be described in a forthcoming paper, can be obtained from the author for collaborative use. The LExS project is part of the planning effort for the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission. The present model of the interaction of solar wind ions with the lunar regolith is embedded in code known as the Lunar Exosphere Simulator (LExS) toolkit. The lunar hydrogen enigma is resolved by showing that exosphere simulations, based on the velocity distribution of transmutative neutral H emerging from the regolith, are compatible with the hydrogen limit of Feldman and Morrison. can be explained by a solar wind-regolith interaction model that includes rapid charge exchange neutralization of incident protons, an inter-atom transport model for fast H in the surface layers of soil grains and rocks, and multiple encounters of free H with loosely packed soil grains. Subsequent discussion will show that the energetic neutral H spectrum reported by Wieser et al. , shed new light on the fate of solar wind protons impinging on the lunar surface. These discoveries, coupled with the very low fluxes of reflected protons reported by Saito et al. The key to resolving the hydrogen enigma lies in recent reports of unexpectedly high fluxes of reflected energetic neutral hydrogen detected by instruments on IBEX and Chandrayaan-1. The purpose of this paper is to challenge the notion that H 2 plays any role in the balance of hydrogen on the moon. This suggestion was followed by Monte Carlo simulations of an H 2 exosphere by Hodges and by Hartle and Thomas, both of which indicated that H 2 concentrations would be so low that the hypothesis of Fastie et al. advanced the notion that protons encountering the lunar regolith might be converted to, and escape as, H 2. Noting that the atomic hydrogen limit is orders of magnitude below preliminary expectations, Fastie et al. A careful reanalysis of the data by Feldman and Morrison raised the terminator limit to 17 cm −3. set the upper bound of H at 10 atoms cm −3 near the terminator. ![]() The initial analyses of the UVS data by Fastie et al. ![]() One of the long-standing puzzles of the Apollo era is the failure of the far-ultraviolet spectrometer (UVS) on the Apollo 17 Command Module to detect resonantly scattered Lyman- α in the lunar exosphere that would confirm the common wisdom that solar wind protons that impact with the lunar surface are released to the exosphere as thermalized neutral hydrogen atoms. The remaining 0.5%, which exit as neutral H atoms with sub-escape speeds, form a tenuous exosphere that is compatible with the levels of Lyman- α allowed by Apollo 17 observations. Overall, the theory indicates that roughly 1% of solar wind protons incident on the lunar regolith surface exit as energetic protons, and about 98.5% exit as neutral H with super-escape speeds. A new theory for the interaction of solar wind with the lunar regolith surface is tested by comparing simulated spectra of reflected energetic neutral hydrogen and protons with analogous neutral spectra from Chandrayaan-1 and proton data from the Kaguya mission. The recent discovery, by instruments on the IBEX and Chandrayaan-1 spacecraft, of significant fluxes of energetic hydrogen atoms escaping from the moon suggests that there are flaws in the common wisdom regarding the interaction of solar wind with lunar regolith that have prevailed in attempts to explain the failure of the Apollo 17 far-ultraviolet spectrometer to detect neutral H in the lunar exosphere. ![]()
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