two-line element set

The term two-line element set (TLE) refers to a data format used to record and report the position and orbits of artificial satellites orbiting Earth, providing the data necessary for prediction of a satellite's position at a future time. The format includes information to identify the spacecraft, its orbital elements, and information regarding characteristics of its motion at a point in time, including its orbital decay. The format was developed in the 1960s when data processing was introduced to assist in tracking satellites. The format was designed to be appropriate for 80-column punched cards (using two of them for a TLE), i.e., with columns assigned to fixed-length fields. The format has undergone some adjustments over time but still fits in 160 bytes.