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The TLE format will soon run out of numbers. The US Space Force is implementing an Alpha 5 scheme where the first byte of the NORAD_ID will be a letter giving nearly 400,000 numbers. After that a 9-digit scheme will be implemented.

The OMM and GP classes, https://public.ccsds.org/Pubs/502x0b2c1.pdf, are Unsigned INT(10) which is a 32 bit unsigned integer field (with 10 visible digits).

What, however is the 9-digit field? Is it a TLE format? XML? JSON? is it bit? base10?

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  • $\begingroup$ different but related (and there may be some helpful links): Will the new “TLE format” be orbitally-mechanically better than traditional TLEs? $\endgroup$
    – uhoh
    Sep 11 '20 at 3:12
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    $\begingroup$ I continue to look into this and I 'think' the answer is that they will abandon the TLE and go with the OMM standard from the CCSDS BlueBook. The following is a excerpt from table 4.3. "NORAD Catalog Number (‘Satellite Number’) an integer of up to nine digits. This keyword is only required if MEAN_ELEMENT_THEORY=SGP/SGP4. " $\endgroup$
    – Barry vT
    Sep 11 '20 at 3:19
  • $\begingroup$ That could be. I don't know, I'm no expert on this myself. But I think others will probably add some more information or post an answer in a day or two. $\endgroup$
    – uhoh
    Sep 11 '20 at 3:25
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You are mixing some topics.

The TLE Format is not running out numbers (directly), the 5-digit NORAD ID is and the TLE-Format is not allowing more than 5 digits in the Satellite catalog number field (columns 3-7).

NORAD / USSF are planning to change their designator to a 9 digit number (allowing up to 999 999 999 designated objects), because more than 99 999 known objects are likely in near future.

To fit a number greater than 99 999 into the 5 digit field of a TLE (in the conversation phase), the first digit is exchanged by a letter. Every letter stands for a number. For example (i do not know the real codes) A=00XXXX, B=01XXXX, C= 02XXXX ... Z = 26XXXX. (ISS NID 25544 would be C5544). Another possible system would be, to change for NID grater 99 999 (A=10XXXX, ISS would stay 25544, object 123456 would be C3456). This would be only needed till the last subsystem is changed from TLEs to its successor. And this is called the Alpha-5 sheme.

The successor is a modified CCSDS OMM, and has no problem handling more than 9 digit numbers, as it is not saved in a fixed column stlye but in whatever computers can read (KVN, JSON, XML...). When this foramt is fully implemented in all subsystem, the alpha-5 notation can be abondoned, which will be the dead of the good old TLE.

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  • $\begingroup$ thank you for the Answer CallMeTom, I believe we can continue this thread in this manner? Regarding the numbering, I believe the USSF assigns the TLE number NORAD_CAT_ID to both debris and launches. Does NASA assign the OBJECT_ID as per an old standard? The Alpha-5 is only good for the TLE methods and the CCSDS says the 9-digit successor is a TLE-only field. Will the longer term future suggest that the OBJECT_ID will be the primary 'key' to the data? $\endgroup$
    – Barry vT
    Sep 12 '20 at 14:55
  • $\begingroup$ I am note really sure, what you mean but the NORAD ID is an upcounting number for every object NORAD identifies. No matter if it is a screw or the Int.Sp.Station. There is an object, they can idetifiy it, it gets an NORAD ID. The other ID, or the "OBJECT_ID" is, if you stick to CCSDS the "international designator" given by COSPAR, a kind of UN Organisation. This "COSPAR ID" consists of the year of the launch, an upcounting number for the launch of that year and an upcounting designator for the object related to this launch. Also the NID is a NORAD-internal development, it gain int. popularity. $\endgroup$
    – CallMeTom
    Sep 12 '20 at 15:06
  • $\begingroup$ Even though the CCSDS puts the 9-digit in a TLE option area within the OMM, do you see it being the primary numbering key for the foreseeable future? The sites are using a 32 bit field for this, so plenty of room if that is the direction. When (not if) the SSA work gets internationalized, do you think the USSF will still assigned the NORAD ID? Are other countries ok with that? $\endgroup$
    – Barry vT
    Sep 12 '20 at 16:49
  • $\begingroup$ In the CCSDS-Standard for OMMs, the field "OBJECT_ID" (Int.Des/Cospar ID) is obligatory, while the "NORAD_CAT_ID" is not. Even the old TLEs had the International Designator in it. On the other hand, the NORAD-ID is handy. I am sure the SF will still assigne NORAD-IDs, for other countries it's swim or sink. The COSPAR-ID will get problems, when objects are found, which cannot be assigned to a specific launch ... Every object, the lauch can be identified will have both. So I would guess, both systems will coexists for the forseeable future. $\endgroup$
    – CallMeTom
    Sep 12 '20 at 19:13

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