Orbit — Live Satellite Tracker (Android)

A clean 3D globe showing real satellites orbiting Earth in real time, plus a live panel of the GNSS satellites your phone is actually using right now, and next-pass / next-rise countdowns for your location. Free, no ads, no in-app purchases, no accounts.

• 3D globe — three.js (WebGL) inside a native WebView. Rotate/zoom with touch.
• Real orbits — Two-Line-Element (TLE) data from Celestrak, propagated on-device with SGP4 (satellite.js).
• "Your phone is using" — Android GnssStatus API, shown as a live sky-plot + count.
• Tap a satellite — country, operator, purpose, NORAD id, altitude, speed, sub-point, look-angle from you, and next pass. Taps go to whichever dot is nearest your finger, at any zoom; a satellite your phone is receiving is shown under its real name, glowing on its own dot.
• The n3d look — the same neumorphic light/dark design as the other n3d apps and sites, following the phone's dark-mode setting live.
• Categories — toggle GPS, GLONASS, Galileo, BeiDou, ISS/Stations, Starlink, Weather, Science.
• No ads, no tracking — the only servers it ever talks to are Celestrak, for orbital data, and n3d-store.com, to check for a new version. Your location is used on-device and never transmitted.

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1. Open & run on your Galaxy S24 (over USB)

1. Install Android Studio (Ladybug or newer).
2. File ▸ Open → select this SatelliteTracker folder. Let Gradle sync (it downloads the Gradle wrapper, AGP, and dependencies automatically the first time).
3. On the S24: Settings ▸ About phone ▸ Software information → tap Build number 7× to enable Developer options. Then Settings ▸ Developer options ▸ USB debugging: ON.
4. Plug the phone in via cable, accept the "Allow USB debugging?" prompt on the phone.
5. In Android Studio pick your device in the toolbar and press ▶ Run.

The debug build installs as a separate app id (com.kotatko.sattracker.debug), so it can sit alongside the release build without either replacing the other.

From the command line instead:

export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"
export ANDROID_HOME="$HOME/Library/Android/sdk"
./gradlew assembleRelease

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2. Distribution

The app is published as a signed APK at https://n3d-store.com/apps.html and linked from the portfolio — not through the Play Store. assembleRelease signs it with the shared n3d release key from ~/.android/n3d-release.properties; without that file the build still succeeds, just unsigned.

Nothing needs replacing before you build. There are no ad ids, no product ids and no API keys anywhere in the project.

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3. The app updates itself (v1.2.0)

Orbit is not on Play, so nothing would otherwise tell anybody a new version exists. Since 1.2.0 the About sheet carries an Updates block that asks n3d-store.com/api/apps/orbit/update what the newest build is, downloads /apk/orbit.apk if it is newer, checks it against the SHA-256 the store published and against this app's own signing certificate, and hands it to Android's package installer — which still shows its own confirmation.

update/Updater.kt is the whole of it and is the same file in all five published apps, differing only in the slug and package name. MainActivity pushes every state change into the sheet through SatBridge.onUpdate(), so the JavaScript holds no update state of its own.

It also looks by itself, at most once a day, silently — no spinner and no error if the phone is offline. That is switchable in the sheet.

4. Ads and in-app purchases were removed (v1.1.0)

Up to v1.0.0 this app carried an AdMob banner and a one-time "remove ads" Play Billing purchase, both wired up with Google's sample/test ids. Both were taken out completely in v1.1.0, because neither can work outside the Play Store: sideloaded, the banner would only ever have shown test ads and the purchase button could not have completed at all.

What went, so nothing here is half-removed:

Removed	Where
play-services-ads, billing-ktx dependencies	app/build.gradle.kts
BillingManager.kt	deleted
SatApp.kt (existed only to call MobileAds.initialize)	deleted, and android:name dropped from the manifest
AdView field, setupAds(), adaptiveBannerSize(), applyProState(), ad lifecycle calls	MainActivity.kt
buyPro() / restorePurchases()	WebAppInterface.kt (both sides of the bridge)
com.google.android.gms.permission.AD_ID, the AdMob <meta-data>, admobAppId placeholder	AndroidManifest.xml / build.gradle.kts
admob_banner_unit_id, pro_product_id	strings.xml
adContainer banner slot	activity_main.xml, now a plain FrameLayout around the WebView
"Remove ads" button, purchase sheet, state.isPro, SatBridge.onPro	globe.html / globe.js

One thing deliberately kept: the CSS class .btn.pro was doing double duty as the lit state of the GNSS and log toggles, so it was renamed to .btn.active rather than deleted — deleting it would have silently killed the highlight on two buttons that have nothing to do with ads.

The settings sheet, which used to be the purchase sheet, is now a short About panel with the data attribution in it.

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5. If you ever do publish it to Play

• Build a signed App Bundle (Build ▸ Generate Signed Bundle / APK) rather than an APK.
• Host a privacy policy URL — mandatory because the app requests location. PRIVACY_POLICY.md is a filled-in starting point.
• Complete the Data safety form: Location, used on-device, not shared, not collected.
• Content rating, category (Tools or Education), screenshots, feature graphic, icon.
• The app no longer uses an advertising id, so that whole branch of the questionnaire is a "no".

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6. Architecture

WebView (assets/globe.html · globe.js · styles.css)   ← 3D globe + all UI, orbit math (SGP4)
        ▲  window.SatBridge.*            window.Android.*  ▼
MainActivity (Kotlin)
 ├─ GnssTracker        → live "satellites in use" (GnssStatus)
 ├─ LocationProvider   → observer lat/lon (FusedLocation)
 └─ TleRepository      → Celestrak TLE fetch + disk cache + assets fallback

• three.js, OrbitControls, satellite.js and the Earth texture are bundled locally in assets/lib/ and loaded as plain <script> tags — no CDN, no ES-module import map. This is required so the app loads correctly from file:///android_asset and works fully offline. (An earlier version loaded these from a CDN as ES modules; that fails in a real WebView loaded from file://, leaving the app stuck on the loading screen.)
• A watchdog in globe.html force-clears the loading overlay after 12 s and surfaces any script error, so the app can never hang silently on boot.
• TLE data is cached for 3 h (TleRepository.CACHE_TTL_MS) to respect Celestrak's fair-use policy. On first launch with no network, the app falls back to the bundled snapshots in assets/tle/.

7. Data sources & attribution

• Orbital elements: Celestrak (T.S. Kelso). Please keep within their access policy.
• Propagation: satellite.js (MIT). Rendering: three.js (MIT).
• Satellite metadata (country/operator/purpose) is a curated best-effort map in globe.js (resolveMeta). For richer data, integrate the Celestrak SATCAT or UCS Satellite Database.

8. Known limitations / next steps

• GNSS "in use" satellites can't be matched 1:1 to catalog objects (PRN vs NORAD id), so they're shown in their own sky-plot rather than highlighted on the 3D globe. This is technically correct.
• Starlink is capped (see CATEGORIES[].cap in globe.js) to keep the globe readable and fast.
• Regular phones (incl. the S24) don't route calls/data through comms satellites, so only positioning (GNSS) satellites are genuinely "in use." Everything else is tracked/visualized.

License

MIT — see LICENSE. Built by Danny (K0tatkoo); installable builds are on n3d-store.com/apps.