Two Line Element Set

Learning more about TLEs

We previously talked about Satellite Tracking and mentioned Two-Line Element (TLE) sets.

At this point, my understanding of TLE is that it’s an old-fashioned data format created in the 70s, which the Space Industry is stuck with. From Wikipedia: “The TLE format is a de facto standard for distribution of an Earth-orbiting object’s orbital elements”.

SpaceTrack provides an API that lets you query the TLE of most non-classified space objects. It even provides an easy-to-use Query Builder tool!

I just used SpaceTrack’s Query Builder to craft this query. The json response contains the TLE of the ISS (fun fact: Zarya is the name of the first module of the ISS).

ISS (ZARYA)
1 25544U 98067A   98324.28472222 -.00003657  11563-4  00000+0 0  9996
2 25544 051.5908 168.3788 0125362 086.4185 359.7454 16.05064833    05

I used Python library TLE-tools to parse that TLE data.

SpaceTrack json output	TLE parsed with `TLE-tools`

I’m still digesting TLE, but I already know what will be my first space-related API: a TLE parser. More on that soon!