Read a satellite's launch year from one TLE parser

The catalog stored the designator on satrec.intldesg for
internationalDesignatorYear, while the active-TLE lookup parsed the same
columns with tleLineLaunchYear. Each catalog entry now keeps launchYear from
tleLineLaunchYear, which moves to src/sources/tle.js beside the other TLE
field readers, and internationalDesignatorYear goes.

A blank designator now reads as an unknown year in both lookups; the
active-TLE lookup read it as 2000.

src/layers/satellites/catalog.js

@@ -1,6 +1,6 @@
 import * as Cesium from 'cesium';
 import { twoline2satrec } from 'satellite.js';
-import { noradIdFromSatnum } from '../../sources/tle.js';
+import { noradIdFromSatnum, tleLineLaunchYear } from '../../sources/tle.js';
 import {
   DENSE_REFRESH_FRAMES,
   DENSE_GROUP_PATH,
@@ -114,8 +114,6 @@ export function createCatalog({ state: layerState, services, parts, source }) {
           const entry = entries[i];
           const satrec = twoline2satrec(entry.line1, entry.line2);
           if (!satrec || satrec.error !== 0) continue;
-          // satellite.js omits the designator the launch-year match reads.
-          satrec.intldesg = entry.line1.slice(9, 17).trim();
           const noradId = noradIdFromSatnum(satrec.satnum);
           if (layerState._catalog.has(noradId)) continue; // core catalog keeps priority
           const pos = parts.orbits.propagatePosition(satrec, now);
@@ -125,6 +123,7 @@ export function createCatalog({ state: layerState, services, parts, source }) {
             name: entry.name,
             satrec,
             group: 'dense',
+            launchYear: tleLineLaunchYear(entry.line1),
           });
           const point = layerState._pointCollection.add({
             position: Cesium.Cartesian3.fromDegrees(

src/layers/satellites/ingestion.js

@@ -1,7 +1,7 @@
 import { twoline2satrec } from 'satellite.js';
 import * as Cesium from 'cesium';
 import { msg } from '../../i18n/index.js';
-import { noradIdFromSatnum } from '../../sources/tle.js';
+import { noradIdFromSatnum, tleLineLaunchYear } from '../../sources/tle.js';
 import { CATALOG_GROUPS, ISS_NORAD, POINT_STYLES } from './policy.js';
 
 export function createIngestion({
@@ -119,8 +119,6 @@ export function createIngestion({
         for (const entry of allEntries) {
           const satrec = twoline2satrec(entry.line1, entry.line2);
           if (!satrec || satrec.error !== 0) continue;
-          // satellite.js omits the designator the launch-year match reads.
-          satrec.intldesg = entry.line1.slice(9, 17).trim();
 
           const noradId = noradIdFromSatnum(satrec.satnum);
           if (seen.has(noradId)) continue;
@@ -131,6 +129,8 @@ export function createIngestion({
             name: entry.name,
             satrec,
             group: entry.group,
+            // satellite.js does not keep the designator the year match reads.
+            launchYear: tleLineLaunchYear(entry.line1),
           });
 
           coreStale ||= entry.stale;

src/layers/satellites/ingestion.test.mjs

@@ -1,6 +1,6 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { parseTleText } from '../../sources/tle.js';
+import { parseTleText, tleLineLaunchYear } from '../../sources/tle.js';
 import { createIngestion } from './ingestion.js';
 import { createOrbits } from './orbits.js';
 
@@ -98,3 +98,24 @@ test('a mission payload does not match a loaded satellite from another launch ye
   assert.equal(track('2026-06-29T02:25:00Z')?.noradId, 69728);
   assert.equal(track('2030-06-29T02:25:00Z'), null);
 });
+
+test('a satellite with a blank designator keeps matching by name', async (t) => {
+  t.mock.method(console, 'log', () => {});
+  t.mock.method(console, 'warn', () => {});
+  const { state, update } = ingestionFor(
+    [
+      'SXM-11',
+      '1 69728U          26208.65166678  .00000015  00000+0  00000+0 0  9990',
+      '2 69728   0.0784 264.9826 0001797 240.4588 273.9506  1.00271527   440',
+    ].join('\n'),
+  );
+  await update();
+  const { getSatelliteOrbitTrack } = createOrbits({ state });
+  assert.equal(tleLineLaunchYear('1 69728U          26208.65166678'), null);
+  assert.equal(
+    getSatelliteOrbitTrack('Sirius SXM-11', {
+      launchTime: '2030-06-29T02:25:00Z',
+    })?.noradId,
+    69728,
+  );
+});

src/layers/satellites/orbits.js

@@ -8,7 +8,11 @@ import {
   twoline2satrec,
 } from 'satellite.js';
 import { findNextSatellitePass } from '../../data/satellitePass.js';
-import { noradIdFromSatnum, parseTleText } from '../../sources/tle.js';
+import {
+  noradIdFromSatnum,
+  parseTleText,
+  tleLineLaunchYear,
+} from '../../sources/tle.js';
 import { ORBIT_PATH_STEPS, ISS_NORAD } from './policy.js';
 
 export function createOrbits({ state: layerState, services, parts, source }) {
@@ -258,13 +262,6 @@ export function createOrbits({ state: layerState, services, parts, source }) {
     return score;
   }
 
-  function internationalDesignatorYear(satrec) {
-    const match = String(satrec?.intldesg || '').match(/^(\d{2})/);
-    if (!match) return null;
-    const shortYear = Number(match[1]);
-    return shortYear >= 57 ? 1900 + shortYear : 2000 + shortYear;
-  }
-
   function lookupTleEntries(tleText) {
     if (tleText !== layerState._lookupTleText) {
       layerState._lookupTleText = tleText;
@@ -273,12 +270,6 @@ export function createOrbits({ state: layerState, services, parts, source }) {
     return layerState._lookupTleEntries;
   }
 
-  function tleLineLaunchYear(line1) {
-    const shortYear = Number(String(line1 || '').slice(9, 11));
-    if (!Number.isFinite(shortYear)) return null;
-    return shortYear >= 57 ? 1900 + shortYear : 2000 + shortYear;
-  }
-
   function orbitTrackFromRecord(name, satrec) {
     const referenceDate = new Date();
     const current = propagatePosition(satrec, referenceDate);
@@ -350,7 +341,7 @@ export function createOrbits({ state: layerState, services, parts, source }) {
         : null;
       let bestScore = 0;
       for (const [id, sat] of layerState._catalog) {
-        const designatorYear = internationalDesignatorYear(sat.satrec);
+        const designatorYear = sat.launchYear ?? null;
         if (
           launchYear !== null &&
           designatorYear !== null &&
@@ -379,7 +370,6 @@ export function createOrbits({ state: layerState, services, parts, source }) {
     getNextSatellitePass,
     resolveSatelliteForPass,
     scoreSatelliteNameMatch,
-    internationalDesignatorYear,
     lookupTleEntries,
     tleLineLaunchYear,
     orbitTrackFromRecord,

src/sources/tle.js

@@ -72,3 +72,16 @@ export function tleCatalogNumber(line) {
   const field = String(line).slice(2, 7);
   return decodeCatalogField(field.replace(/^ +/, ''));
 }
+
+/**
+ * Launch year from TLE line 1's international designator (columns 10-11);
+ * null when the designator is blank.
+ * @param {string} line1
+ * @returns {number|null}
+ */
+export function tleLineLaunchYear(line1) {
+  const digits = String(line1 || '').slice(9, 11);
+  if (!/^\d{2}$/.test(digits)) return null;
+  const shortYear = Number(digits);
+  return shortYear >= 57 ? 1900 + shortYear : 2000 + shortYear;
+}