On a recent episode of the Planetary Radio podcast, the topic of Third-Order Acronyms was brought up. At NASA, there are many Second-order acronyms like SAFER - Simplified Aid For EVA Rescue, where there is an acronym inside of an acronym. Are there any acronyms inside of acronyms inside of acronyms (Third Order) used in space exploration?

EDIT: Initialisms are also accepted.

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    $\begingroup$ Acronyms are a dime a dozen at NASA. I vaguely recall running across a fourth order acronym at some point in my career, but the recollection is vague. All I remember was "Wow. A fourth order acronym." $\endgroup$ Commented Sep 13, 2019 at 17:02
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    $\begingroup$ I know of plenty of (often jocular) infinite-order acronyms. Not necessarily specific to space exploration, but possibly used by some people at NASA. Linux developers seem to love them, e.g. "PINE": "PINE Is Not ELM", or "GIMP": "GIMP Is Mainly Photoshop", etc. (I'm aware they have other meanings, Linux people are just like that sometimes.) Then there was Dilbert's "The TTP Project", where the second 'T' stands for "The TTP Project". $\endgroup$ Commented Sep 13, 2019 at 18:48
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    $\begingroup$ @DarrelHoffman GIMP is a double-infinite acronym! GIMP is also named GNU Image Manipulation Program, where GNU is “GNU’s Not Unix” $\endgroup$ Commented Sep 14, 2019 at 3:25
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    $\begingroup$ @DarrelHoffman: Googling "GIMP Is Mainly Photoshop" returns exactly one result: your comment. $\endgroup$ Commented Sep 14, 2019 at 19:20
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    $\begingroup$ @CourageousPotato: Also: It's time [to] explain the meaning of "Hurd". "Hurd" stands for "Hird of Unix-Replacing Daemons". And, then, "Hird" stands for "Hurd of Interfaces Representing Depth". We have here, to my knowledge, the first software to be named by a pair of mutually recursive acronyms. See here. $\endgroup$ Commented Sep 14, 2019 at 19:22

5 Answers 5



  • NUTI => NASCOM User Traffic Interface
  • NASCOM => NASA Communications
  • NASA => National Aeronautics and Space Administration

Found by parsing this list of over 14,000 NASA acronyms

It also contains a vast number of second order acronyms, but the example above is the only third order acronym I could find through initial analysis.

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    $\begingroup$ That's 14,000 Shuttle acronyms. It isn't a complete list of Shuttle-related acronyms, and it's only Shuttle-related acronyms. $\endgroup$ Commented Sep 13, 2019 at 17:07
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    $\begingroup$ @DavidHammen One black swan disproves the "all swans are white" fallacy. The question asks "are there any", this shows there are. $\endgroup$ Commented Sep 13, 2019 at 17:08
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    $\begingroup$ @OrganicMarble I think David was taking issue with it being described as "NASA acronyms" when it is only a subset of Shuttle acronyms, but if so I'm not sure that hair splitting is relevant. The list is NASA acronyms, it just so happens to be a subset of NASA acronyms that only includes Shuttle acronyms. $\endgroup$
    – called2voyage
    Commented Sep 13, 2019 at 17:55
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    $\begingroup$ By the way, if you change "program=shuttle" to "program=station" in the URL, you got a long list of some Space Station acronyms. $\endgroup$
    – called2voyage
    Commented Sep 13, 2019 at 20:49

I gave an example of one a while back in this answer:

enter image description here

Alternate version by Magic Octopus Urn

enter image description here

Alternate version by Eric Duminil

enter image description here

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    $\begingroup$ Is there any way to draw this diagram that isn't a little bit confusing? $\endgroup$ Commented Sep 13, 2019 at 13:44
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    $\begingroup$ Knock yourself out! $\endgroup$ Commented Sep 13, 2019 at 13:51
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    $\begingroup$ @Hohmannfan I guess if I had drawn it with the 1st acronym at the bottom and run the arrows up, I could have listed the words in forward instead of reverse order. That might have been a better choice. Odds of me redoing it are slim though. $\endgroup$ Commented Sep 13, 2019 at 14:07
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    $\begingroup$ @MadPhysicist that would work too. I'm too top-down, left-to-right biased apparently. $\endgroup$ Commented Sep 13, 2019 at 17:36
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    $\begingroup$ Feel free to use this one if you think it's better. $\endgroup$ Commented Sep 14, 2019 at 19:32

While not exactly space exploration there is at least one fourth order acronym for NASA earth observation systems (mostly earth sensing satellites).

  • EPR - EED2 Program Roadmap
  • EED - EOSDIS Evolution and Development
  • EOSDIS - Earth Observation System(EOS) Data and Information System
  • EOS - Earth Observing System

NASA - EOSDIS Acronym List

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    $\begingroup$ Is the last step really an expansion though? $\endgroup$ Commented Sep 13, 2019 at 21:32
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    $\begingroup$ That’s just a third order - EOS is already expanded in EOSDIS. $\endgroup$
    – Tim
    Commented Sep 13, 2019 at 22:39
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    $\begingroup$ It kind of is, because "Earth Observation System Data and Information System" is lousy grammar, but "EOS Data and Information System" where "EOS" is a proper noun works nicely. So it really kind of "wants" to be unexpanded at the third level. $\endgroup$
    – hobbs
    Commented Sep 15, 2019 at 1:53

There's a conference about satellite sounders called the

ITSC: International TOVS Study Conference

organised by the

ITWG: International TOVS Working Group


TOVS: TIROS Operational Vertical Sounder


TIROS: Television Infrared Observation Satellite


VERITAS mission to Venus (proposed).


VERITAS - Venus Emissivity, Radio science, InSAR, Topography And Spectroscopy

InSAR - Intrerferometric Synthetic Aperture Radar

Radar - Radio Detection And Ranging


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