PhosphorOrbit

PhosphorOrbit transforms your iPhone into a Cold War-era space surveillance terminal. Built around a real-time polar radar scope, it tracks every catalogued object in Earth orbit using official NORAD data from CelesTrak and the US Space Force 18th Space Defense Squadron.

The app renders satellite positions on an azimuth/elevation polar projection centred on your location. The International Space Station, Starlink constellations, dead Soviet-era satellites, Chinese rocket body debris — everything currently overhead appears as a phosphor blip on your personal radar scope, updating every few seconds via SGP4 orbital propagation.

RADAR SCOPE
The primary display is a full-screen polar radar showing all tracked objects above your horizon. Pinch to zoom up to 6x magnification and drag to pan across crowded orbital shells. Objects are classified by type — space stations, active payloads, Starlink satellites, rocket bodies, and debris — each with distinct glyphs and colour coding. Tap any object for detailed orbital data including altitude, velocity, azimuth, elevation, and range. Filter by classification to focus on what matters.

PASS PREDICTIONS
A comprehensive pass predictor computes upcoming visible satellite passes for your location over the next 24 hours. Passes are grouped by date with estimated apparent magnitude, maximum elevation, and visibility status. Tap any pass to open a detail view featuring a sky track polar diagram — a mini radar plot showing exactly where the satellite will travel across the sky from rise to set, with compass bearings at every point. If a pass is currently in progress, a live tracking dot shows the satellite's real-time position on the arc.

GROUND TRACK
A Mercator projection displays the selected satellite's ground track with past and future orbit traces, the day/night terminator line, and your observer position with its visibility circle.

ORBITAL DENSITY
A shell histogram visualises object density by altitude band, colour-coded by type. See at a glance where the most congested orbital shells are — the 550km Starlink band, the sun-synchronous corridors around 800km, and the debris-choked zones in between.

KESSLER DASHBOARD
The existential dread panel. Tracks total catalogued objects, the debris-to-payload ratio, spatial density in critical altitude bands, and a composite Kessler Index illustrating how close major orbital shells are to runaway debris cascading. Includes a timeline of major debris-generating events and current Starlink collision avoidance manoeuvre rates.

OFFLINE RESILIENCE
TLE orbital data is cached locally. When connectivity drops, the app continues operating from cached data — SGP4 propagation remains accurate for days. A live network monitor detects reconnection and automatically refreshes data. Clear indicators show data source status at all times.

CRT AESTHETIC
PhosphorOrbit is part of the Phosphor suite of apps sharing a signature retro display aesthetic. Choose from phosphor green, amber, or white colour themes. Metal shader scanlines, phosphor glow effects, and monospace typography complete the look — SHADO's Space Intruder Detector from UFO (1970), except real, running on your iPhone.

All orbital data is freely available from CelesTrak. No account or subscription required.
Position calculations use SGP4/SDP4 — the same propagation model used by space agencies worldwide.