// ORBITAL LOGISTICS AND PROPULSION TERM
Two-Line Element
A Two-Line Element, often shortened to TLE, is a specific format of data that provides all the essential information needed to calculate and predict the path of an orbiting object. It's called "two-line" because the data is presented in two lines of text.
TECHNICAL DEFINITION
A Two-Line Element (TLE) is a specific, compact data format, typically generated by NORAD, that encapsulates a satellite's orbital parameters (e.g., epoch, inclination, right ascension of the ascending node, eccentricity, argument of perigee, mean anomaly, mean motion) for propagation and state vector determination.
BACKGROUND
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. It is the largest telescope in space, and is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, distant, or faint for the Hubble Space Telescope. This enables investigations across many fields of astronomy and cosmology, such as observation of the first stars and the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets.
READ MORE ON WIKIPEDIASYNONYMS & ALIASES
- TLE
- NORAD TLE
- orbital element set
- satellite element data
USAGE NOTE
Software tools use Two-Line Elements to propagate satellite orbits and generate ephemerides.
DEVELOPERS
Organizations developing technology related to Two-Line Element.
The 18th Space Defense Squadron (part of Space Delta 2) is responsible for maintaining the Space Catalog and providing Two-Line Element (TLE) data for all trackable objects in Earth orbit. They are the primary source for public TLE data.
LeoLabs develops and operates a global network of radars to track objects in low Earth orbit (LEO), providing high-resolution orbital data, space situational awareness services, and often compares and refines TLEs, as well as generating more precise ephemerides.
Through its Space Safety Programme and Space Debris Office, ESA performs space surveillance and tracking (SST) activities, including monitoring space objects, maintaining a catalogue, and performing conjunction analysis, all of which heavily rely on orbital data formats like TLEs.
Ansys Government Solutions (formerly AGI) develops Systems Tool Kit (STK), a widely used software for space mission analysis, design, and operations. STK extensively uses TLEs for propagating orbits, performing conjunction analysis, and simulating space scenarios.
Planet Labs operates the world's largest fleet of Earth observation satellites. They utilize TLEs and other orbital data formats for tracking their own satellites, predicting their positions, managing their constellation, and performing collision avoidance maneuvers.
SpaceX operates the Starlink satellite constellation and develops reusable launch vehicles. They are heavily involved in satellite tracking, collision avoidance, and orbital management for their vast constellation, which inherently involves the use and processing of TLEs and other precise orbital data.
Astroscale is a company focused on on-orbit servicing and space debris removal. Their operations require extremely precise knowledge of satellite orbits and debris trajectories, utilizing TLEs as a baseline and often generating more refined ephemeris data for rendezvous and proximity operations.
As a major aerospace and defense technology company, Northrop Grumman is involved in satellite manufacturing, space situational awareness (SSA) systems, and related space technologies. They utilize TLEs and other orbital data for mission planning, operations, and defense applications.