Perigee MCPサーバー

perigee-mcp

An MCP server for Perigee, the open-source 3D viewer of the artificial objects orbiting the Earth, the Moon and Mars and of the spacecraft crossing the solar system. It lets an AI assistant (a teaching assistant, for example) answer questions such as “how far is Mars from the Earth on 1 December 2026?”, “where is the ISS now?” or “what is Lucy's mission?”, and hand the student a live 3D view, with how each number was obtained, from which data, how fresh and how accurate.

Educational use only: not for navigation, collision avoidance or conjunction assessment.

Use it

Claude Desktop (claude_desktop_config.json) or any MCP client that starts servers over stdio:

{
  "mcpServers": {
    "perigee": { "command": "npx", "args": ["-y", "perigee-mcp"] }
  }
}

Claude Code: claude mcp add perigee -- npx -y perigee-mcp. Node.js 20 or later.

Hosted, nothing to install: the same tools at https://perigee-mcp.perigeeinfo.workers.dev/mcp (Streamable HTTP, no account, a budget of 60 units a minute per address, a tool call costing 1 to 4). Claude.ai: Settings → Connectors → Add custom connector with that URL; Claude Code: claude mcp add --transport http perigee https://perigee-mcp.perigeeinfo.workers.dev/mcp. Distance series are limited to 100 samples, pass searches to 3 days and event searches to 31 days there. The hosted endpoint keeps a short usage log (tool, object asked about, outcome; never your address or place coordinates; see the privacy page).

Tools

Every computed answer has a provenance list: the model (SGP4 from CelesTrak GP or supplemental GP elements, Hermite interpolation of JPL Horizons vectors, two-body extrapolation, VSOP87 for planets, analytical or mean-element moons), the data state (fresh, interpolated, stale, extrapolated, hidden, modelled, none), when the data were fetched, the age of the orbital elements, the ephemeris window, and a typical accuracy with its basis.

Data

Positions are computed on your machine with the same code as the web app, from the data Perigee publishes at https://perigee.info/data/ (CelesTrak elements refreshed every 4 hours, JPL Horizons ephemerides daily). Each dataset version is downloaded once and kept in a cache (%LOCALAPPDATA%\perigee-mcp, ~/Library/Caches/perigee-mcp or ~/.cache/perigee-mcp; PERIGEE_MCP_CACHE overrides it). The server never contacts CelesTrak or Horizons. PERIGEE_SITE points it to another Perigee deployment.

Credits: CelesTrak (T.S. Kelso) / 18th & 19th SDS via Space-Track, NASA/JPL-Caltech Horizons, astronomy-engine (MIT), satellite.js (MIT); catalogue images under the licence given with each. Code: MIT, https://github.com/dlamarre-dev/Perigee.