TLE Satellite Catalog Number

Hi all,

After talking with some colleagues, they told me about the possibility that the Satellite Catalogue Number (SCN) for TLE could be changed from 5 digits to 9 digits. The reason is that the 5-digit format may soon no longer be sufficient to support the growing number of space objects.

So I did some research and came across an article from 2013 showing that this format change is planned for 2019 1. I also came across a Twitter post from March 2020 saying that OneWeb had fun using the 9-digit format for their TLE on Spacetrack 2.

Currently, the official format is still 5 digits. However, if it had to be changed to 9 digits, the modification, certainly trivial to achieve, should be done in Orekit.

As I’m not a big TLE user and I know that there are a lot of people using TLE on this forum :wink:, I wonder if you have any information about this possible change of format?

Thank you,

I’ve heard of various proposals along those lines, but I haven’t heard of one being officially implemented by 18 SPCS, though T. S. Kelso would probably be the first to know and implement it if it happened.


As Evan said, I’ve heard lots of chatter about it for some time but I’ve seen nothing concrete yet.

Dr. T. S. Kelso is very active on Twitter, he would surely let everyone know too!

Dr. T. S. Kelso has published a new article related to this, on May 27th 2020.