ba1212361f
Commit the previously-untracked standard directories and catalog them in the
root README alongside proof:
- aac/ — communication cargo class: portable boards + a ten-level
offline-first cascade (Apache-2.0 code / CC-BY-4.0 spec).
- map/ — geospatial cargo class: range-requestable signed tilesets +
an F0–F4 fidelity cascade (Apache-2.0 code / CC-BY-4.0 spec).
- sandbox/— isolated, metered, attested execution across the heterogeneous
compute fabric (Apache-2.0 code / CC-BY-4.0 spec).
- jouleclaw-otel-authz, jouleclaw-trust — new jouleclaw reference crates.
Root README now lists aac, map, sandbox, and proof in the catalog, the tree,
and the contribution guide.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
91 lines
3 KiB
Rust
91 lines
3 KiB
Rust
//! SGP4 physical constants from Vallado's "Revisiting Spacetrack Report #3" (2006).
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//!
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//! WGS-72 constants used by the SGP4 propagator for compatibility with
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//! NORAD TLE element sets. WGS-84 constants used for geodetic transforms.
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use std::f64::consts::PI;
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// ── WGS-72 constants (SGP4 propagator) ──────────────────────
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/// Gravitational parameter of Earth (km^3/s^2), WGS-72 value.
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pub const MU: f64 = 398600.8;
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/// Earth equatorial radius (km), WGS-72.
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pub const EARTH_RADIUS_KM: f64 = 6378.135;
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/// XKE = 60.0 / sqrt(a_E^3 / mu) where a_E in km, mu in km^3/s^2.
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/// This is sqrt(GM) in units of earth-radii^1.5 / min.
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pub const XKE: f64 = 0.07436685316871385;
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/// KE = sqrt(GM_Earth) in earth-radii^1.5 / min (same as XKE for WGS-72).
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pub const KE: f64 = 0.0743669161;
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/// Velocity conversion: km/s per (earth-radii/min).
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pub const VKMPERSEC: f64 = EARTH_RADIUS_KM * XKE / 60.0;
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/// J2 zonal harmonic, WGS-72.
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pub const J2: f64 = 1.08262998905e-3;
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/// J3 zonal harmonic, WGS-72.
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pub const J3: f64 = -2.53215306e-6;
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/// J4 zonal harmonic, WGS-72.
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pub const J4: f64 = -1.61098761e-6;
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/// J3 / J2 ratio (used frequently in SGP4).
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pub const J3OJ2: f64 = J3 / J2;
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/// CK2 = 0.5 * J2 * a_E^2 (in SGP4 normalized units).
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pub const CK2: f64 = 0.5 * J2;
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/// CK4 = -3/8 * J4 * a_E^4 (in SGP4 normalized units).
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pub const CK4: f64 = -0.375 * J4;
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// ── General constants ────────────────────────────────────────
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/// Two pi.
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pub const TWOPI: f64 = 2.0 * PI;
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/// Minutes per day.
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pub const MINUTES_PER_DAY: f64 = 1440.0;
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/// Seconds per day.
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pub const SECONDS_PER_DAY: f64 = 86400.0;
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/// Degrees to radians conversion factor.
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pub const DEG_TO_RAD: f64 = PI / 180.0;
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/// Radians to degrees conversion factor.
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pub const RAD_TO_DEG: f64 = 180.0 / PI;
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// ── WGS-84 constants (geodetic transforms) ──────────────────
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/// Earth equatorial radius (km), WGS-84.
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pub const EARTH_RADIUS_WGS84: f64 = 6378.137;
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/// Earth polar radius (km), WGS-84.
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pub const EARTH_POLAR_RADIUS: f64 = 6356.752314245;
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/// WGS-84 flattening.
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pub const FLATTENING: f64 = 1.0 / 298.257223563;
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/// WGS-84 first eccentricity squared: 2f - f^2.
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pub const EARTH_ECCENTRICITY_SQ: f64 = 2.0 * FLATTENING - FLATTENING * FLATTENING;
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/// WGS-84 second eccentricity squared: (a^2 - b^2) / b^2.
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pub const EARTH_ECCENTRICITY_SQ2: f64 =
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(EARTH_RADIUS_WGS84 * EARTH_RADIUS_WGS84 - EARTH_POLAR_RADIUS * EARTH_POLAR_RADIUS)
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/ (EARTH_POLAR_RADIUS * EARTH_POLAR_RADIUS);
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/// Earth rotation rate (rad/s), WGS-84.
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pub const OMEGA_E: f64 = 7.292115e-5;
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/// Threshold for near-earth vs deep-space branching (minutes).
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/// Satellites with period >= 225 minutes use SDP4.
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pub const DEEP_SPACE_THRESHOLD_MIN: f64 = 225.0;
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/// Small value for floating-point comparisons.
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pub const SMALL: f64 = 1.0e-12;
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/// Maximum iterations for Kepler's equation solver.
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pub const MAX_KEPLER_ITERATIONS: u32 = 10;
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