marss 0.0.3

Mars celestial simulation crate for the MilkyWay SolarSystem workspace
Documentation 
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use sciforge::hub::domain::astronomy::orbits::escape_velocity;
use sciforge::hub::domain::common::constants::G;

pub struct Impactor {
    pub mass_kg: f64,
    pub velocity_m_s: f64,
    pub density_kg_m3: f64,
    pub angle_deg: f64,
}

impl Impactor {
    pub fn asteroid(diameter_m: f64, velocity_km_s: f64) -> Self {
        let density = crate::STONY_ASTEROID_DENSITY;
        let radius = diameter_m / 2.0;
        let volume = (4.0 / 3.0) * std::f64::consts::PI * radius.powi(3);
        Self {
            mass_kg: density * volume,
            velocity_m_s: velocity_km_s * 1000.0,
            density_kg_m3: density,
            angle_deg: 45.0,
        }
    }

    pub fn iron_asteroid(diameter_m: f64, velocity_km_s: f64) -> Self {
        let density = crate::IRON_ASTEROID_DENSITY;
        let radius = diameter_m / 2.0;
        let volume = (4.0 / 3.0) * std::f64::consts::PI * radius.powi(3);
        Self {
            mass_kg: density * volume,
            velocity_m_s: velocity_km_s * 1000.0,
            density_kg_m3: density,
            angle_deg: 45.0,
        }
    }

    pub fn kinetic_energy_j(&self) -> f64 {
        0.5 * self.mass_kg * self.velocity_m_s.powi(2)
    }

    pub fn kinetic_energy_mt(&self) -> f64 {
        self.kinetic_energy_j() / crate::MT_TNT_TO_JOULE
    }

    pub fn impact_velocity(&self) -> f64 {
        let v_esc = escape_velocity(G * crate::MARS_MASS, crate::MARS_RADIUS);
        (self.velocity_m_s.powi(2) + v_esc.powi(2)).sqrt()
    }

    pub fn crater_diameter_m(&self, target_density: f64) -> f64 {
        let g = crate::SURFACE_GRAVITY;
        let angle_rad = self.angle_deg.to_radians();
        let d_projectile =
            (6.0 * self.mass_kg / (std::f64::consts::PI * self.density_kg_m3)).cbrt();
        1.161
            * (self.density_kg_m3 / target_density).powf(1.0 / 3.0)
            * d_projectile.powf(0.78)
            * self.velocity_m_s.powf(0.44)
            * g.powf(-0.22)
            * angle_rad.sin().powf(1.0 / 3.0)
    }

    pub fn fireball_radius_m(&self) -> f64 {
        let energy_kt = self.kinetic_energy_j() / crate::KT_TNT_TO_JOULE;
        55.0 * energy_kt.powf(0.4)
    }

    pub fn ejecta_volume_m3(&self, target_density: f64) -> f64 {
        let crater_d = self.crater_diameter_m(target_density);
        let crater_depth = crater_d / 5.0;
        std::f64::consts::PI / 6.0 * crater_d * crater_d * crater_depth
    }

    pub fn ejecta_escape_fraction(&self) -> f64 {
        let v_esc = escape_velocity(G * crate::MARS_MASS, crate::MARS_RADIUS);
        let ratio = self.velocity_m_s / v_esc;
        (ratio * 0.05).min(0.5)
    }
}

pub fn hellas_impactor() -> Impactor {
    Impactor::asteroid(500_000.0, 10.0)
}

pub fn typical_mars_crosser() -> Impactor {
    Impactor::asteroid(100.0, 8.0)
}