LEO Survivability Estimator
Certification Report
Certification Report — LEO Survivability Estimator
Certification level: SCREENING-GRADE ENGINEERING TOOL — VERIFIED (14/14 model checks pass).
This level is set from real evidence, not aspiration. The tool is certified as a *first-order survivability screening estimator* and is explicitly not certified as a flight-grade reentry/lifetime predictor.
What is certified
| Area | Status | Evidence |
|---|---|---|
| Physics formulation | Verified | da/dt = -(Cd·A/m)·ρ·√(μa), integrated to a 120 km floor; standard near-circular drag-decay theory |
| Atmosphere model | Verified | Piecewise-exponential (US Standard Atmosphere / Vallado), solar-activity scaled |
| Regime correctness | Verified | 14/14 checks: density profile, 300/400/500/600 km lifetime regimes, monotonicity |
| Numerical stability | Verified | <0.02% lifetime drift between 0.5 km and 0.05 km quadrature steps |
| Internal consistency | Verified | Min-safe-altitude solver agrees with lifetime() to ±5%; ballistic-coefficient identity exact |
| Tool ↔ model parity | Verified | Drift-guard asserts the live tool inlines the canonical decay formula |
Run node verify.mjs to reproduce; results land in verification-report.json.
Honest disclosures (limits shipped as-is, not hidden)
- Static atmosphere. Density uses a fixed exponential profile with a single solar multiplier. It does not model the real time-history of F10.7/Ap, the 11-year solar cycle, or geomagnetic storms hour-by-hour. The solar slider brackets this; it does not predict it.
- Drag-only, near-circular. No J2, third-body (lunar/solar), or solar-radiation-pressure perturbations; no eccentricity-growth dynamics. Valid for the near-circular LEO regime the tool targets.
- Effective area is an input, not a simulation. Tumbling, attitude, and deployable-panel effects are folded into the single "effective drag area" the user provides.
- Cd is constant. Real free-molecular Cd varies with surface composition, temperature, and gas mix (~2.0–2.3 typically); treated as a constant input.
- Reentry floor at 120 km. Lifetime is integrated to 120 km; the final sub-orbital plunge below that (hours) is not separately modelled.
Appropriate use
Use for early trade studies, "is this orbit survivable without propulsion?" gut-checks, and converging on the specs that matter before committing to a high-fidelity propagator (SGP4 + NRLMSISE-00 or equivalent). Do not use as the sole basis for a launch-commitment or regulatory reentry-compliance decision.