🌐 English · 한국어
See which satellites are flying over each country, in real time.
Quick Start
🛰️ Live: satlas.space
▶ Watch the demo on YouTube
Existing satellite tracking tools answer one of two questions:
| Perspective | Representative Tools | Question Answered |
|---|---|---|
| Observer-based | Heavens-Above, Stellarium | "Can I see this satellite from my location?" |
| Ownership-based | UCS Satellite Database | "Which country built this satellite?" |
Satlas takes a third perspective — country-based: "Which satellites pass over this country, and when?"
Before Satlas, answering this required walking through each satellite's orbit manually or fitting coordinate-based tools to a national boundary. Satlas reduces it to a single country click.
This project was inspired by an aircraft surveillance display I came across during my service in the Air Force, which shows aircraft activity around a country in real time. The framing — what's flying over our sky right now — stuck with me. Years later, on a night walk, I noticed bright dots moving overhead. Most of them turned out to be satellites. Searching online, I found 3D globes that placed satellites in orbit and 2D tools that traced individual orbits, but nothing that answered the same question in satellite terms: which satellites are over this country right now. With launches accelerating, the gap felt worth filling.
- 🗺️ Click any country on a 2D world map → every satellite currently overhead
- 🏷️ Filter by category — Starlink, GPS, weather, science, military, ...
- 📅 Upcoming passes for the next 24 hours, grouped by 1 h / 6 h / 24 h windows
- 🛰️ Track a satellite — its real-time footprint and 95-minute ground track on the map
- 📊 Global dashboard — active catalog totals, category breakdown, most-overflown countries today, recent launches
Click a country — every satellite currently overhead, with category filters and a 24-hour pass schedule.
Dashboard — active catalog totals, category breakdown, most-overflown countries today, recent launches.
Track a satellite — real-time position, footprint, and 95-minute ground track.
| Layer | Technologies |
|---|---|
| Backend | Python 3.11 · FastAPI · PostgreSQL · Redis · Celery · APScheduler · SGP4 |
| Frontend | React · Vite · TypeScript · Leaflet · satellite.js |
| Infra | Docker Compose · Fly.io · Vercel · GitHub Actions |
| Data | CelesTrak (TLE + SATCAT) · Natural Earth (country polygons) |
Every significant architectural choice is recorded as an ADR — what was decided, what alternatives were rejected, and what trade-offs were paid. Full index: docs/adr/ (25 ADRs).
Selected highlights:
- ADR-005 — TLE storage strategy: twice-daily snapshots + phased pre-computation
- ADR-014 — Deployment platform: Fly.io (backend) + Vercel (frontend)
- ADR-018 — Overhead refresh: server-side window prediction + client-side gating
- ADR-024 — Chunked recompute + Redis list schema (fixes the OOM cliff past 15k satellites)
- ADR-025 — IP-geo language pick + per-locale OG image variants
| Source | Purpose | License |
|---|---|---|
| CelesTrak | TLE orbital elements + SATCAT metadata (operator country, launch date, object type). Fetched twice daily as GP JSON | Free public service, no API key |
| Natural Earth | Country boundary polygons for satellite-over-country intersection | Public Domain |
Space-Track.org (US Space Force) is being evaluated as a supplementary historical TLE source and may be added in a future phase. Registration is free but required.
- 🌐 Custom domain (satlas.space) + locale-aware OG image previews + first-visit IP-geo language pick — ADR-025
- 🔍 SEO baseline — robots.txt, sitemap.xml, JSON-LD WebApplication schema, Google Search Console
- 📋
/aboutpage — friendly intro, sources, limits, privacy - 📊 Dashboard — global catalog, category bars, top-overflown countries, recent launches
- 📅 24-hour pass schedule — 1 h / 6 h / 24 h grouping, panel tab toggle
- 💧 Chunked recompute + Redis list schema — bounds memory regardless of catalog size — ADR-024
- 🚀 Public launch — Fly.io + Vercel + GitHub Actions push model
- Space and satellite enthusiasts curious about what's overhead right now
- Students learning orbital mechanics, satellite operations, or space situational awareness
- Researchers analysing satellite pass patterns over specific countries
Contributing guidelines will be available in CONTRIBUTING.md.
Bug reports and feature requests are welcome via Issues.