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Technology

The technical stack behind Call a Satellite — from orbital data ingestion to real-time voice conversations with spacecraft.

01

Orbital Data

Call a Satellite ingests Two-Line Element (TLE) datasets published by CelesTrak, sourced from the NORAD satellite catalog maintained by the 18th Space Defense Squadron. These datasets contain the orbital parameters for every tracked object in Earth orbit, updated multiple times per day.

  • TLE datasets from CelesTrak with regular updates
  • NORAD catalog numbers for unique satellite identification
  • Keplerian orbital elements: inclination, eccentricity, RAAN, argument of perigee, mean anomaly, and mean motion
02

Orbit Propagation

Satellite positions are computed using the SGP4 (Simplified General Perturbations 4) algorithm, implemented via the satellite.js library. SGP4 takes TLE data as input and outputs precise position and velocity vectors at any point in time, accounting for Earth's oblateness and atmospheric drag.

  • SGP4 propagation algorithm for position and velocity computation
  • satellite.js — a JavaScript implementation of SGP4/SDP4
  • Accurate predictions for low-Earth and medium-Earth orbit satellites
03

Real-Time Tracking

Once propagated, each satellite's telemetry is presented in real time. The system continuously recalculates orbital state to deliver live updates throughout every call.

  • Current latitude, longitude, and altitude
  • Orbital velocity and ground speed
  • Ground track projection on the globe
  • Overhead satellite detection relative to the user's location
  • Orbital period, apogee, and perigee
04

AI Conversation Engine

Each satellite has a unique conversational persona powered by an AI language model. The conversation engine receives live orbital telemetry and translates it into natural, personality-driven responses so the spacecraft can describe what it sees and where it is.

  • GPT-4o-mini for low-latency, context-aware dialogue
  • Persona-based responses unique to each satellite's mission
  • Real telemetry woven into natural conversation
05

Voice Interface

Call a Satellite supports full voice interaction. Users speak naturally and hear the satellite respond with synthesized speech, creating an experience that feels like a real phone call with a spacecraft.

  • Web Speech API for browser-native speech recognition
  • ElevenLabs text-to-speech for high-quality voice output
  • Low-latency voice pipeline for natural conversation flow
06

3D Globe Visualization

An interactive 3D globe renders the satellite's position, orbit path, and ground track in real time. Users can see exactly where the spacecraft is relative to continents, oceans, and their own location.

  • CesiumJS for hardware-accelerated 3D globe rendering
  • ArcGIS satellite imagery basemap
  • Real-time orbit path and ground track overlays