moons 0.0.3

Moon celestial simulation crate for the MilkyWay SolarSystem workspace
Documentation 
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use sciforge::hub::prelude::constants::elements::atomic_mass;

pub struct ExosphereSpecies {
    pub name: &'static str,
    pub symbol: &'static str,
    pub molar_mass_kg_mol: f64,
    pub column_density_m2: f64,
    pub scale_height_m: f64,
}

pub struct ExosphereEndpoint {
    pub body_radius_m: f64,
    pub species: Vec<ExosphereSpecies>,
}

fn he_molar() -> f64 {
    atomic_mass(2) * 1e-3
}
fn ne_molar() -> f64 {
    atomic_mass(10) * 1e-3
}
fn ar_molar() -> f64 {
    atomic_mass(18) * 1e-3
}
fn na_molar() -> f64 {
    atomic_mass(11) * 1e-3
}
fn k_molar() -> f64 {
    atomic_mass(19) * 1e-3
}
fn h_molar() -> f64 {
    atomic_mass(1) * 1e-3
}

impl ExosphereEndpoint {
    pub fn moon() -> Self {
        Self {
            body_radius_m: crate::MOON_RADIUS_M,
            species: vec![
                ExosphereSpecies {
                    name: "Helium",
                    symbol: "He",
                    molar_mass_kg_mol: he_molar(),
                    column_density_m2: 4e13,
                    scale_height_m: 420_000.0,
                },
                ExosphereSpecies {
                    name: "Neon",
                    symbol: "Ne",
                    molar_mass_kg_mol: ne_molar(),
                    column_density_m2: 2e13,
                    scale_height_m: 250_000.0,
                },
                ExosphereSpecies {
                    name: "Argon-40",
                    symbol: "Ar",
                    molar_mass_kg_mol: ar_molar(),
                    column_density_m2: 1e14,
                    scale_height_m: 100_000.0,
                },
                ExosphereSpecies {
                    name: "Sodium",
                    symbol: "Na",
                    molar_mass_kg_mol: na_molar(),
                    column_density_m2: 1e13,
                    scale_height_m: 120_000.0,
                },
                ExosphereSpecies {
                    name: "Potassium",
                    symbol: "K",
                    molar_mass_kg_mol: k_molar(),
                    column_density_m2: 1e11,
                    scale_height_m: 90_000.0,
                },
                ExosphereSpecies {
                    name: "Atomic hydrogen",
                    symbol: "H",
                    molar_mass_kg_mol: h_molar(),
                    column_density_m2: 1e12,
                    scale_height_m: 1_000_000.0,
                },
            ],
        }
    }

    pub fn density_at_altitude(&self, species_symbol: &str, altitude_m: f64) -> f64 {
        self.species
            .iter()
            .find(|s| s.symbol == species_symbol)
            .map(|s| {
                let n_surface = s.column_density_m2 / s.scale_height_m;
                n_surface * (-altitude_m / s.scale_height_m).exp()
            })
            .unwrap_or(0.0)
    }

    pub fn total_column_density(&self) -> f64 {
        self.species.iter().map(|s| s.column_density_m2).sum()
    }

    pub fn sodium_glow_intensity(&self) -> f64 {
        self.species
            .iter()
            .find(|s| s.symbol == "Na")
            .map(|s| s.column_density_m2 * 1e-13)
            .unwrap_or(0.0)
    }
}