{
  "tool": "cargo-mass-optimizer",
  "author": "calvin-jacobs",
  "version": "1.0.0",
  "description": "Payload vs. buffer tradeoff optimizer for extreme-route logistics. Applies Tsiolkovsky rocket equation to compute feasible payload given dry mass, specific impulse, and delta-v requirement.",
  "formula": {
    "equation": "m₀ = m_dry × exp(Δv / (I_sp × g₀))",
    "variables": {
      "m₀": {
        "symbol": "m₀",
        "description": "Initial total mass (vehicle + propellant + payload)",
        "unit": "tonnes"
      },
      "m_dry": {
        "symbol": "m_dry",
        "description": "Dry mass (structure + engines + avionics, no propellant)",
        "unit": "tonnes"
      },
      "Δv": {
        "symbol": "Δv",
        "description": "Required velocity change",
        "unit": "m/s"
      },
      "I_sp": {
        "symbol": "I_sp",
        "description": "Specific impulse (engine efficiency)",
        "unit": "seconds"
      },
      "g₀": {
        "symbol": "g₀",
        "value": 9.80665,
        "description": "Standard gravity",
        "unit": "m/s²",
        "source": "CODATA 2018"
      }
    },
    "derived": {
      "exhaust_velocity": "v_e = I_sp × g₀",
      "mass_ratio": "MR = m₀ / m_dry = exp(Δv / v_e)",
      "propellant_mass": "m_prop = m₀ − m_dry",
      "payload_capacity": "m_payload ≤ m₀ × (target_pct / 100) − m_dry × overhead_factor"
    }
  },
  "constraints": {
    "min_isp": 200,
    "max_isp": 1000,
    "typical_isp_options": [
      {"profile": "LOX/LH₂ sea-level", "isp": 310},
      {"profile": "LOX/LH₂ vacuum", "isp": 363},
      {"profile": "Nuclear thermal", "isp": 450},
      {"profile": "Ion thruster", "isp": 3000}
    ],
    "structural_overhead_default": 0.05,
    "viability_threshold": "payload ≥ 0.1 × dry_mass"
  },
  "analogs": {
    "terrestrial": {
      "vessel": "Paul R. Tregurtha",
      "class": "Laker freighter",
      "draft_capacity_tonnes": 12000,
      "operational_constraint": "ice thickness vs. cargo weight",
      "source_url": "https://www.pexels.com/photo/paul-r-tregurtha-cargo-ship-on-great-lakes-5049941/"
    },
    "mission_profiles": [
      {"name": "Low Lunar Orbit insertion", "dv_km_s": 2.58, "notes": "Earth departure + LOI burn"},
      {"name": "Lunar surface ascent", "dv_km_s": 2.38, "notes": "LSA to LLO"},
      {"name": "Trans-Mars injection", "dv_km_s": 3.6, "notes": "LEO to TMI"}
    ]
  },
  "links": {
    "homepage": "https://calvin-jacobs.4ort.net/",
    "parent_tool": "https://calvin-jacobs.4ort.net/route-buffer-calculator.html",
    "inventory_protocol": "https://calvin-jacobs.4ort.net/inventory-protocol.html"
  },
  "license": "CC0-1.0",
  "created": "2026-07-17T19:00:00Z"
}