Science

Two-Body State Vector Propagator

Propagate a spacecraft/satellite state vector (r₀, v₀) to time t₀+Δt under two-body gravity via the universal-variable (f-and-g) method, and derive the classical orbital elements

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Quick start

Call this tool from your code in three languages.

cURL

curl -X POST 'https://api.elysiatools.com/en/api/tools/two-body-state-vector-propagator' \
  -H 'Content-Type: application/json' \
  -d '{"centralBody":"earth","customMu":0,"distUnit":"km","r0":"7000,0,0","v0":"0,7546,0","dt":3600}'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/two-body-state-vector-propagator

Parameters

Name	Type	Required	Description
centralBody	select	No	—
customMu	number	No	—
distUnit	select	No	—
r0	text	Yes	—
v0	text	Yes	—
dt

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-two-body-state-vector-propagator": {
      "name": "two-body-state-vector-propagator",
      "description": "Propagate a spacecraft/satellite state vector (r₀, v₀) to time t₀+Δt under two-body gravity via the universal-variable (f-and-g) method, and derive the classical orbital elements",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=two-body-state-vector-propagator",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "two-body-state-vector-propagator",
    "arguments": {
  "centralBody": "earth",
  "customMu": 0,
  "distUnit": "km",
  "r0": "7000,0,0",
  "v0": "0,7546,0",
  "dt": 3600
}
  }
}

Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

Questions or issues? Contact [email protected]

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