This document contains confidential data and is not intended to be shared outside of SAGE!
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| Last Updated | 10/12/2025, 12:48:54 PM |
| Last Author | Kai Berszin |
What is TLE
Two-Line Elements (TLE) is a data format used to encode a list of orbital elements at a given time. The Format has its origins in early space exploration and was intended to be saved on two 80-column punch cards. The information in a TLE can be used to propagate the trajectory using the appropriate tools.
Orbit Determination with publicly available TLEs
The website space-track.org provides two-line elements (TLEs) to the public. SPACETRACK is maintained by the U.S. Air Force Combined Space Operations Center (CSpOC), which until recently was known as the Joint Space Operations Center (JSpOC). CSpOC maintains a catalog of space objects and freely provides TLEs and other space situational awareness data for these objects. This data can be obtained via a simple API.
Example API query for the most recent TLE
The space-track.org website provides a query builder and a list of example queries. In most cases, we are only interested in retrieving the most recent TLE for SAGE.
Important: should not be called more than once per hour by an automated script to avoid rate limiting
SAGE NORAD Catalog ID
After SAGE has been successfully deployed in space, CSpOC will assign SAGE a unique identification code known as a NORAD_CAT_ID. This ID can be used to retrieve SAGE's TLE and other data via the API.
SAGE Placeholder Sattelite IDs
These are three sattelites with similar characteristics (size, orbit) to SAGE. These can be used to test the pipeline until SAGE is launched.
PREFIRE-1 NORAD: 59965 Incl: 97.48 Apogee: 521 Perigee: 504 Info: Small NASA Science Mission
JILIN-01-10 NORAD: 43946 Incl: 97.48 Apogee: 515 Perigee: 502 Info: Chinese earth observation sattelite
JAY-D1 NORAD: 62669 Incl: 97.44 Apogee: 517 Perigee: 507 Info: Canadian military observation sattelite
Additional CubeSat ID's can be found at the following website.
SAGE Credentials
To query the space-track.org API (for a TLE, conjunction messages, etc.), the user or script must provide a username and password. A Login is easily created on their website and confirmed within minutes. For information on the Login or to use existing credentials, please contact Daniel Gotsmann(MOPS Team) (not created as of 5.may 2025).
TLE retrieval code
The space_track_tle_retrieval function takes a NORAD_ID and a type (tle for now) and returns the latest TLE from space_track.org. The tle is returned as a RetrievedTLE class object. This object also contains the source and time of retrieval
Changelog
| Date | Revision | Change |
|---|---|---|
| 2025/02/21 | 01 | Initial commit. |
| 2025/04/03 | 02 | additional info on TLEs, API Login and placeholder sattelites |
| 2025/05/07 | 03 | updated info on code and API requests |