# Project Structure
Structure map for the Titans crate.
```text
Titans/
├── README.md # Project overview and usage
├── LICENSE # MIT license
├── ChangeLog.md # Version history
├── ComingSoon.md # Planned features
├── Contributing # Contribution guidelines
├── lastest_versions.sh # Restore wildcard dependency versions
│
├── src/
│ ├── main.rs # Entry point — Titan diagnostics: orbit, thick atmosphere, methane cycle
│ ├── lib.rs # Library root, TITANMASS (1.35e23 kg), radius 2 575 km, constants
│ │
│ ├── environment/ # Surface environment
│ │ ├── mod.rs # Exports dust, radiation, thermal
│ │ ├── dust.rs # Tholin haze particles settling, organic sand grain transport
│ │ ├── radiation.rs # Dense atmosphere shields surface — minimal GCR/particle flux at ground
│ │ └── thermal.rs # Surface 94 K uniformly, 1.5 atm N₂/CH₄ atmosphere, greenhouse + anti-greenhouse
│ │
│ ├── exosphere/ # Atmosphere model (dense N₂/CH₄ atmosphere, not tenuous exosphere)
│ │ ├── mod.rs # Exports charging, escape, species
│ │ ├── charging.rs # Ionospheric interaction with Saturn magnetosphere, upper atmosphere
│ │ ├── escape.rs # Hydrodynamic escape of H₂, photochemical CH₄ destruction in upper atmosphere
│ │ └── species.rs # N₂ (95%), CH₄ (5%), C₂H₆, C₂H₂, HCN, tholin haze (>100 identified species)
│ │
│ ├── geodata/ # Geographic reference data
│ │ ├── mod.rs # Exports coordinates, elevation, landing_sites, regions
│ │ ├── coordinates.rs # Planetocentric lat/lon, IAU Titan-fixed frame
│ │ ├── elevation.rs # Cassini RADAR altimetry/SAR-derived topography through opaque atmosphere
│ │ ├── landing_sites.rs # Dragonfly target (Selk crater region), Huygens landing (Adiri)
│ │ └── regions.rs # Xanadu continent, Kraken/Ligeia/Punga Maria (north polar seas), Belet Sand Sea
│ │
│ ├── geology/ # Surface and interior geology
│ │ ├── mod.rs # Exports craters, erosion, mountains, regolith, volcanism
│ │ ├── craters.rs # Menrva (392 km), Selk (90 km) — very few craters, young surface
│ │ ├── erosion.rs # Methane rain erosion, fluvial channels, coastal erosion at lake margins
│ │ ├── mountains.rs # Mithrim Montes (~3.3 km), Doom Mons (cryovolcano candidate), ice ridges
│ │ ├── regolith.rs # Organic tholin-coated ice grains, water-ice bedrock beneath
│ │ └── volcanism.rs # Possible cryovolcanism — Doom Mons/Sotra Patera, ammonia-water lavas
│ │
│ ├── interactions/ # Gravitational interactions
│ │ ├── mod.rs # Exports earth_tides, saturns, orbital_dynamics
│ │ ├── earth_tides.rs # Earth–Titan perturbation (negligible at 9.5 AU)
│ │ ├── saturns.rs # Saturn gravitational influence, 4:3 resonance with Hyperion
│ │ └── orbital_dynamics.rs # Eccentric orbit (e = 0.029), tidal interaction with Saturn
│ │
│ ├── lighting/ # Illumination model
│ │ ├── mod.rs # Exports eclipses, saturnshine, solar_position
│ │ ├── eclipses.rs # Saturn shadow transits, ring shadow bands, atmosphere scattering
│ │ ├── saturnshine.rs # Negligible at surface — dense haze blocks all direct/reflected light
│ │ └── solar_position.rs # ~0.1% surface illumination (through haze), 15.95 d orbital period
│ │
│ ├── missions/ # Exploration missions
│ │ ├── mod.rs # Exports landers, orbiters, relay
│ │ ├── landers.rs # Huygens probe (landed 2005-01-14), Dragonfly rotorcraft (~2034 arrival)
│ │ ├── orbiters.rs # Cassini (127 Titan flybys, RADAR mapping), future orbiter concepts
│ │ └── relay.rs # Cassini relay for Huygens, Dragonfly direct-to-Earth link
│ │
│ ├── observation/ # Remote observation
│ │ ├── mod.rs # Exports communications, saturn_view, navigation
│ │ ├── communications.rs # Deep-space link budget, 9.5 AU light-time delay (~79 min)
│ │ ├── saturn_view.rs # Saturn not visible from surface (opaque haze), RADAR mapping only
│ │ └── navigation.rs # Atmospheric navigation, RADAR ground tracking, Doppler wind measurement
│ │
│ ├── physics/ # Orbital and impact mechanics
│ │ ├── mod.rs # Exports collisions, orbit, rotation, tides
│ │ ├── collisions.rs # Atmosphere decelerates impactors, few craters survive
│ │ ├── orbit.rs # a = 1 221 870 km, e = 0.0288, period 15.95 d, vis-viva
│ │ ├── rotation.rs # Synchronous rotation, super-rotation of atmosphere (~4%)
│ │ └── tides.rs # Tidal deformation of ice shell, ocean detection via tidal Love number k₂
│ │
│ ├── rendering/ # Visual rendering pipeline
│ │ ├── mod.rs # Exports atmosphere_scattering, clouds, dust, materials, shaders
│ │ ├── atmosphere_scattering.rs # Rayleigh/Mie scattering through Titan’s thick atmosphere
│ │ ├── clouds.rs # Methane cloud rendering
│ │ ├── dust.rs # Tholin haze particle rendering, orange atmospheric scattering
│ │ ├── lod.rs # Pixel-precise adaptive LOD
│ │ ├── materials.rs # PBR organic sand (dunes), methane lakes (specular), icy bedrock
│ │ ├── mesh.rs # Icosphere subdivision, vertex data
│ │ └── shaders.rs # GPU shader programs — atmospheric haze layers, methane lake reflection
│ │
│ ├── resources/ # Extractable resources
│ │ ├── mod.rs # Exports minerals, regolith, water_ice
│ │ ├── minerals.rs # Organic tholin deposits, complex prebiotic chemistry products
│ │ ├── regolith.rs # Organic sand grains, tholin-coated pebbles, Huygens surface data
│ │ └── water_ice.rs # Water-ice bedrock beneath organics, subsurface ammonia-water ocean
│ │
│ ├── surface/ # Surface mapping
│ │ ├── mod.rs # Exports heightmaps, mapping, zones
│ │ ├── heightmaps.rs # Cassini RADAR/SAR altimetry through opaque atmosphere
│ │ ├── mapping.rs # RADAR-dark (smooth) and RADAR-bright (rough) terrain maps, VIMS composites
│ │ └── zones.rs # Equatorial dune seas, polar lake districts, Xanadu highlands, labyrinth terrain
│ │
│ ├── temporal/ # Time systems
│ │ ├── mod.rs # Exports calendar, epoch, time_scale
│ │ ├── calendar.rs # Titan calendar — 15.95 d orbital period, Saturn year (29.5 yr), methane seasons
│ │ ├── epoch.rs # J2000 epoch, Huygens landing (2005-01-14), Dragonfly arrival timeline
│ │ └── time_scale.rs # TDB/UT1/TAI conversions at 9.5 AU light-time delay
│ │
│ └── terrain/ # Terrain mesh generation
│ ├── mod.rs # Exports lod, mesh, texturing
│ ├── lod.rs # Level-of-detail streaming for dune fields and lake shorelines
│ ├── mesh.rs # Spherical mesh, radius 2 575 km (second-largest moon)
│ └── texturing.rs # Cassini RADAR/VIMS composite drape, organic surface textures
│
├── tests/ # Integration tests
│ ├── environment_tests.rs # Tests 1.5 atm pressure, 94 K surface, tholin settling rate
│ ├── exosphere_tests.rs # Tests N₂/CH₄ atmospheric profile, photochemical destruction rate
│ ├── geodata_tests.rs # Tests coordinate transforms, Kraken Mare shoreline, Selk crater
│ ├── geology_tests.rs # Tests methane fluvial erosion, dune morphology, crater scarcity
│ ├── interactions_tests.rs # Tests Hyperion 4:3 resonance, Love number k₂ ocean detection
│ ├── lighting_tests.rs # Tests haze attenuation (~0.1% surface), Saturn shadow timing
│ ├── missions_tests.rs # Tests Huygens descent profile, Cassini flyby parameters
│ ├── observation_tests.rs # Tests RADAR mapping resolution, Doppler wind measurement
│ ├── physics_tests.rs # Tests orbital period, atmospheric super-rotation, tidal amplitude
│ ├── rendering_tests.rs # Tests haze scattering model, methane lake specular reflection
│ ├── resources_tests.rs # Tests tholin composition, methane lake volume estimates
│ ├── surface_tests.rs # Tests RADAR altimetry resolution, terrain unit classification
│ ├── temporal_tests.rs # Tests methane season cycle, epoch conversions
│ └── terrain_tests.rs # Tests mesh accuracy, LOD transitions at lake shorelines
│
└── examples/ # Runnable examples
├── check_landing_site.rs # Evaluate Dragonfly Selk crater region for rotorcraft operations
├── crater_sim.rs # Menrva/Selk formation through dense atmosphere impactor deceleration
├── eclipse_sim.rs # Saturn shadow transit timing through opaque atmosphere
├── exosphere_sim.rs # N₂/CH₄ atmospheric column, photochemical haze production
├── saturn_observation.rs # Saturn hidden by haze — RADAR-only observation geometry
├── orbital_sim.rs # 15.95-day orbit propagation, Hyperion resonance effects
├── radiation_sim.rs # Atmospheric shielding — minimal surface radiation dose
├── resource_survey.rs # Tholin organic deposit and methane lake distribution mapping
└── tidal_effects.rs # Tidal Love number — subsurface ocean detection via deformation
```