NoradID/TLE Readin Issue

Orekit development
1

All

Now that the Norad ID system is coming close to hitting 70000, space-track is going to be using a new type of NOID called “alpha-5”. An example is:

0 HAWK-15A
1 J2931U 21006CW  26148.66506944  .00003931  00000-0  11826-3 0 99991
2 J2931 097.2338 194.0330 0004500 272.5331 128.7187 15.34417975009998

Question 1: Does Orekit currently have the ability to read alpha-5 TLEs?
Question 2: If the answer to Question 1 is “no”, then can we write a patch to add the ability to read alpha-5 TLEs before SpaceTrack hits ths 70000 NOID? And where would this go - patch-13.1.6?

Thanks
Brianna

2

Hi Brianna,

The alpha 5 parsing has been a feature in Orekit for 5 years or so. Courtesy of Mark Rutten I believe.

Cheers,
Romain.

3

@Serrof Yes I took a better look and I see it now. But I’ve been talking with my team about their request, and it looks like it’s a bit more specific than I initially thought. Right now we have a function in propagation.analytical.tle.TLE that supports reading in a TLE by entering the individual components:

public TLE(final int satelliteNumber, final char classification,
               final int launchYear, final int launchNumber, final String launchPiece,
               final int ephemerisType, final int elementNumber, final AbsoluteDate epoch,
               final double meanMotion, final double meanMotionFirstDerivative,
               final double meanMotionSecondDerivative, final double e, final double i,
               final double pa, final double raan, final double meanAnomaly,
               final int revolutionNumberAtEpoch, final double bStar)

However, we do not have a similar function that accepts a String input in place of the int input for the satelliteNumber value. Would there be any objection by the development team if I put in a work order for this and then wrote a patch-MR to include in patch-13.1.6?

4

Issue #1159 has been completed on the develop branch, providing users with a public method to decode Alpha 5 (conversion from String to int). I guess it could be included in the patch, although it’s more a feature

5

Maybe I could add it as a feature to v14 and then just have my team use a private patch until v14 actually comes out?

6

I’m not super up to another constructor with a gazillion arguments. Is it not satisfactory in your case to chain the decoder from issue #1159 with the existing constructor?

7

Hey @baubin, this isn’t a direct answer to your question, but if your team are getting the TLE information from space-track then they already have access to the integer form of the NORAD ID. The extended TLE formats (KVN/XML/json) have a “NORAD_CAT_ID” which will always be an integer, even for IDs > 70000. You’ll only see the alpha-5 form in the actual two-line format, which is restricted to 5 digits.

8

@markrutten @Serrof Thanks for the help. I’ve talked with my team, and I think I can use the MR that @rsmarcelinoo wrote a couple of months ago to make a patch verison of 13.1.5 that will hold my team over until v14 comes out. @rsmarcelinoo thanks a ton for taking care of that - you made my life easier :slight_smile: