> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rotastellar.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Tick Session

> Advances the simulation by a given duration and returns the updated state

<Note>
  **Base URL:** `https://sim.rotastellar.com`
  — No API key required.
</Note>

### Path Parameters

| Parameter   | Type   | Description                                 |
| ----------- | ------ | ------------------------------------------- |
| `sessionId` | string | The session ID returned from Create Session |

<RequestExample>
  ```bash theme={null}
  curl -X POST https://sim.rotastellar.com/v1/sessions/ses_abc123/tick \
    -H "Content-Type: application/json" \
    -d '{
      "duration_s": 60
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json 200 OK theme={null}
  {
    "session_id": "ses_abc123",
    "epoch": "2026-03-10T12:06:00Z",
    "tick_count": 6,
    "duration_s": 60,
    "satellites": [
      {
        "id": "sat-001",
        "name": "RS-LEO-1",
        "position": { "lat_deg": 33.8, "lon_deg": -114.5, "alt_km": 548.6 },
        "velocity_km_s": 7.59,
        "sunlit": true,
        "subsystems": {
          "power_w": 116,
          "thermal_c": 22.6,
          "comms_dbm": -81,
          "memory_used_mb": 1028
        },
        "faults": []
      }
    ],
    "isl_links": [
      { "from": "sat-001", "to": "sat-002", "distance_km": 1235, "latency_ms": 4.1, "active": true }
    ],
    "events": [
      { "epoch": "2026-03-10T12:05:30Z", "type": "isl_handover", "from": "sat-002", "to": "sat-003" }
    ]
  }
  ```
</ResponseExample>