A Two-Line Element set (TLE) packs an entire orbital description into 69 characters per line. It looks cryptic — but once you know the column layout, you can read orbit altitude, inclination, shape, and epoch directly from the text.
A Two-Line Element set (TLE) packs an entire orbital description into 69 characters per line. It looks cryptic — but once you know the column layout, you can read orbit altitude, inclination, shape, and epoch directly from the text.
Line 1 identifies the object and when the elements were measured.
Line 2 contains the six Keplerian-like mean elements that define the orbit's shape, orientation, and timing.
You don't need to memorise column numbers. Here are the practical quick-reads:
From these three numbers alone, you know: the ISS orbits at about 51.6° inclination, completes ~15.5 orbits per day (~93 minutes each), and has a nearly circular orbit. The altitude is approximately 420 km — derivable from the mean motion.
You now know enough to glance at a TLE and read the orbit type, altitude class, shape, inclination, and data freshness. On Orbital Radar, this is the raw data behind every satellite you see on the globe.