I was confused by the displayed launch date for SpinSat which was carried into space aboard CRS-4 in September 2014, since it is listed as November 20, 1998. It was explained that the date refers to the launch date of Zarya - the first module of the ISS, since SpinSat was deployed into space from the ISS (via the Kibo module airlock.)

Looking at CRS-4, I see 40210 which shows a launch date of September 21, 2012, and 40211 showing a launch date of September 21, 2014. Screenshots below. 40211 seems to be a debris object, and the date is the actual launch date of CRS-4.

Question: However, why is the launch date of 40210 shown as September 21, 2012, and not either September 21, 2014 (CRS-4 actual launch) or November 20, 1998 (ISS "launch date")?

Is the system for applying launch dates to objects involved in docking maneuvers, transfers, or even captures and re-deploys described somewhere? In the future those could become more common.

If I could have followed CRS-4 and SpinSat for the past few years, would their displayed launch dates change as their situation changed?

Screenshots shown below are from http://www.n2yo.com/ circa July 2016:

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  • $\begingroup$ "why is the launch date of 40210 shown as September 21, 2012": that looks like a typo, probably 2014 was intended. $\endgroup$
    – Hobbes
    Sep 19, 2018 at 7:32
  • $\begingroup$ @Hobbes I didn't spot that; yes the calendar date "September 21" is the same in both, which strongly suggests a typo rather than something more complicated. If there are no other subtleties here, then that could turn out to be the entire answer. $\endgroup$
    – uhoh
    Sep 19, 2018 at 7:45
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    $\begingroup$ I'm pretty sure @Hobbes is right. I could write it as an answer, but I'd feel a bit of a cheat getting the bounty! $\endgroup$
    – djr
    Sep 19, 2018 at 19:52
  • $\begingroup$ @djr Main goals in SE include writing of good answers and bringing future readers to those answers. Why not add a bit of helpful information to your answer so you'll feel better about it (for example, roughly how many times does 1998-067 appear in raw satcat data? celestrak.com/satcat/search.php) there's a Q&A here somewhere that address what to do when we run out of three-letter suffixes (e.g. 1998-067ZZZ) or some other aspect of the situation you feel would be interesting to future readers. Just a thought. $\endgroup$
    – uhoh
    Sep 20, 2018 at 4:18
  • $\begingroup$ @djr I understand your quandary but the SE bounty mechanism is fairly rigid. I can't withdraw it, so either it gets awarded to an answer or it disappears. If you like I could defer to another answer if an additional one is posted, or not-award it to you if so requested, but it's already out there, so... $\endgroup$
    – uhoh
    Sep 20, 2018 at 4:19

1 Answer 1


What we know:

  • CRS-4 was launched 21 Sep 2014 (Multiple sources).
  • Spinsat was deployed from ISS/Kibo on 28 Nov 2014 (Gunter's)
  • International designator for Spinsat: 1998-067FL
  • NORAD Catalog ID for Spinsat: 40314

As mentioned in the comments, the launch date of "21 Sep 2012" for CRS-4 on n2yo.com is clearly a typo.

As for the broader question of deployments from other vehicles (intentional or not), the "launch date," as was mentioned, is based on the launch date of the deploying vehicle. Thus Spinsat's launch date is listed as 20 Nov 1998 which was the launch date of the first ISS module.

In a similar fashion, all the debris cataloged from the Iridum 33 collision in 2009 has a launch date of 14 Sep 1997.

Because launch date drives the international designators - All ISS deployments are 1998-067## (only at two letters for now). For Iridium they are 1997-051### (the highest it goes is 1997-051ABD). I've verified this on space-track.org which is the web site fed directly from the JSPOC. Celestrak gets its data from space-track.

Interestingly, the NORAD Catalog number is NOT based on launch date, but on catalog order. Thus the ID for Spinsat is 40314 vs CRS-4 which is 40210 If we look at the catalog, 40312 (2014-074A ) is a Soyuz launched Nov 23 2014, just a few dates before Spinsat's deployment. 40313 is the Soyuz rocket body.

Since both space-track and Celestrak capture "launch date" based on the deployer date, rather than the object actually going into space, it becomes hard to find out when something actually launched.

A great resource is Jonathan's space report, which keeps track of actual launch dates, as well as catalog and international IDs. His launchlog file is an unwidely text file, but you can do lots of magic with it in Excel, Matlab, Python or yourfavorite processing code.

  • $\begingroup$ Your answer is complete, as well as chock-full of background information, thanks. I didn't know that Celestrak's source was direct from Space-Track, and I had no idea about the size of 1997-051! In their counting system, would ABD be the 732nd combination? $\endgroup$
    – uhoh
    Sep 20, 2018 at 16:43
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    $\begingroup$ Yeah, I'd never checked 1997-051 either until now. And that is just the stuff they track! $\endgroup$
    – Carlos N
    Sep 20, 2018 at 17:07
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    $\begingroup$ Another piece of evidence for it being a typo is that there were no orbital launches on 21 Sep 2012 (see Jonathan McDowell planet4589.org/space/jsr/back/news.668.txt for the relevant time if you don't want to look at the entire launchlog). $\endgroup$
    – djr
    Sep 20, 2018 at 20:48

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