Initial commit

backend/services/satellites.py

@@ -0,0 +1,105 @@
+from skyfield.api import load
+import asyncio
+
+SATELLITE_GROUPS = {
+    "military":   "https://celestrak.org/NORAD/elements/gp.php?GROUP=military&FORMAT=tle",
+    "stations":   "https://celestrak.org/NORAD/elements/gp.php?GROUP=stations&FORMAT=tle",
+    "navigation": "https://celestrak.org/NORAD/elements/gp.php?GROUP=gnss&FORMAT=tle",
+}
+
+GROUP_LIMITS = {
+    "military":   800,
+    "stations":   50,
+    "navigation": 120,
+}
+
+satellites_data: dict = {}
+
+
+def load_satellites():
+    """
+    Blocking I/O: loads TLE data from Celestrak.
+    Must be called via asyncio.to_thread to avoid blocking the event loop.
+    """
+    global satellites_data
+    try:
+        ts = load.timescale()
+        loaded = {}
+        for group, url in SATELLITE_GROUPS.items():
+            try:
+                filename = f"{group}.tle"
+                sats = load.tle_file(url, filename=filename)
+                loaded[group] = sats
+                print(f"[SPACE] {group}: {len(sats)} satellites loaded.")
+            except Exception as e:
+                print(f"[SPACE] Failed to load {group}: {e}")
+        satellites_data = {**loaded, "ts": ts}
+    except Exception as e:
+        print(f"[SPACE] Critical load failure: {e}")
+
+
+def _compute_positions_sync(sats: list, category: str, t, limit: int) -> list:
+    """
+    CPU-bound position computation — runs in a thread executor.
+    Returns dicts, does NOT mutate shared state.
+    """
+    positions = []
+    for sat in sats[:limit]:
+        try:
+            geocentric = sat.at(t)
+            subpoint = geocentric.subpoint()
+            lat = subpoint.latitude.degrees
+            lon = subpoint.longitude.degrees
+            alt = subpoint.elevation.m
+
+            if not (-90 <= lat <= 90) or not (-180 <= lon <= 180):
+                continue
+
+            positions.append({
+                "id":       sat.model.satnum,
+                "name":     sat.name,
+                "lat":      lat,
+                "lon":      lon,
+                "alt":      alt,
+                "category": category,
+                "type":     "satellite"
+            })
+        except Exception:
+            pass  # skip satellites with bad TLE data
+    return positions
+
+
+async def get_satellite_positions() -> list:
+    if "ts" not in satellites_data:
+        # First run: load everything in a background thread
+        await asyncio.to_thread(load_satellites)
+
+    if "ts" not in satellites_data:
+        print("[SPACE] Satellite data unavailable.")
+        return []
+
+    t = satellites_data["ts"].now()
+    all_positions = []
+
+    for group, limit in GROUP_LIMITS.items():
+        if group in satellites_data:
+            result = await asyncio.to_thread(
+                _compute_positions_sync,
+                satellites_data[group],
+                group,
+                t,
+                limit
+            )
+            all_positions.extend(result)
+
+    print(f"[SPACE] {len(all_positions)} satellite positions computed.")
+    return all_positions
+
+
+if __name__ == "__main__":
+    load_satellites()
+    positions = asyncio.run(get_satellite_positions())
+    print(f"Total: {len(positions)}")
+    from collections import Counter
+    for cat, count in Counter(p["category"] for p in positions).items():
+        print(f"  {cat}: {count}")