Ballistic and gas dispersion simulation

🇫🇷 Version française : LISEZMOI.md

▶️ Launch the simulation — 📖 technical documentation (French)

One single standalone HTML file — no dependency, no installation, no server.

Dispersion simulation tool for the Guiana Space Centre (CSG / Kourou) and other launch pads worldwide. It computes the fallout path of ballistic debris and the atmospheric dispersion of HCl released by the boosters. User interface in French.

Files

File	Description
dispersion_v62.html	Main application — open it directly in the browser
dispersion_doc.html	Full technical documentation (architecture, ETS, models), in French

Features

Module	Description
Launch pads	CSG (ELA-4, ELV, ELS), Florida, Vandenberg, Baikonur, Plesetsk, Vostochny, Wenchang, Jiuquan, Xichang, Tanegashima, Sriharikota
RK45 ballistics	Adaptive Dormand-Prince integrator · tabulated Cd(Mach) · 7-layer ISA atmosphere · Coriolis force
Gas dispersion	Pasquill-Gifford model, classes A→F automatic · Turner σ (1970) · AEGL-1/10 HCl threshold = 0.1 mg/m³
Real-time weather	Open-Meteo vertical profile (wind, pressure, humidity) — HTTPS GET request, no personal data
Mapping	Esri World Imagery + Esri labels, no key, no API · fallout zones · AEGL contours · wind barbs
Touch map	One-finger pan, pinch-to-zoom
Web Workers	Parallel non-blocking computation
Security	Strict CSP · watchdog · built-in sanity checks

Deployment

Open the link above, or download dispersion_v62.html and open it in a modern browser. No installation, no server, no administrator rights required.

Only two outgoing network calls:

Destination	Purpose	Data sent
api.open-meteo.com	Vertical wind profile	Launch pad lat/lon only
server.arcgisonline.com	Esri map tiles (no key)	Tile coordinates (zoom/x/y)

Security & IT audit

Source code in clear — not minified, not obfuscated. Readable in any text editor.

• No external library · no CDN · no supply-chain attack surface
• No cookie · no localStorage · no disk write
• All computation data in RAM only

Physical models

• Atmosphere — standard 7-layer ISA
• Integrator — adaptive RK45 Dormand-Prince
• Aerodynamics — tabulated Cd(Mach)
• Coriolis — force included in the state vector
• Dispersion — Pasquill-Gifford A→F · Turner coefficients (1970) · 6 classes
• Operational threshold — AEGL-1/10 = 0.1 mg/m³ (HCl)

History

Version	Change
6.0	RK45 ballistics, Pasquill-Gifford, open-meteo wind profile, Web Workers, strict CSP
6.1	Touch map: one-finger pan, pinch-to-zoom
6.2	Esri base map without key or API, CARTO tiles removed
6.3	AZS visual identity (app and documentation), link back to www.azs.fr, light / dark documentation

Disclaimer

This tool is an operational decision aid. It does not replace the official safety systems of the CSG nor the regulatory procedures in force. Results must be interpreted by qualified staff.

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© Eric Perret 2026 · v6.3 · www.azs.fr