@Conelisinspace shouldn't the astrobiology tag be for non terrestrial native life forms? I don't think it applies to tardigrades any more than it does to to mold, plants, mice, or people on the ISS. – uhoh 2 hours ago

@uhoh I read that the astrobiology tag is for questions about the study of life outside the Earth. I don't know if ISS is considered to be outside. – Conelisinspace 1 hour ago

@uhoh Should not the description of the tag contain "extraterrestial life" , with the origin of life outside the Earth? – Conelisinspace 1 hour ago

@Conelisinspace let's be practical. Using your definition, we would have to tag every single question on the site that involves biology in space. That's impractical, and it renders the tag to mean just biology in space. What would be the most helpful way for the tag to be used, and how has it been used on this site until now? If people are following the tag, then suddenly using it in a new and clever way may upset the apple cart. – uhoh 31 mins ago

Quoted from: Have water bears ever been studied on the ISS or in Space?

What is the community's thoughts on the astro-biology tag, and the life tag?

Biology shouldn't be aliased to Life?

Personal opinion:

should be used to tag the experimentation with life, from earth, in space or the study of biological processes involving earth, while in space.

should be reserved for the cultivation of intelligent life in space or discovery of extra-terrestrial organisms/life on external planets.

Or visa-versa, they're both kind of synonymous and the descriptions for the tags are ambiguous and (honestly) not very good, I believe they should be updated, but to what I have no idea.


2 Answers 2


Astrobiology is usually used for the study of whether life can/does exist beyond the Earth (see, for example, here). I think we should stick to that usage.

The life tag has been used in a really broad way, but it is pretty consistently used here for the use of Earth life in the space enterprise (though not exclusively used for that). I think we should stick to that usage.

  • $\begingroup$ Hah! So I got them exactly backwards, let me go ahead and swiiitch those around before anyone notices... $\endgroup$ Oct 11, 2018 at 14:45
  • $\begingroup$ So astrobiology could also be used to study if water bears can exist beyond the Earth ? $\endgroup$
    – Cornelis
    Oct 11, 2018 at 15:18
  • $\begingroup$ Agreed, this is the definition of astrobiology as I've always understood it $\endgroup$
    – Jack
    Oct 11, 2018 at 15:45
  • $\begingroup$ @Conelisinspace Technically, the idea is the existence of life not native to Earth. While it is possible water bears are not native, I find that to be unlikely. $\endgroup$
    – called2voyage Mod
    Oct 11, 2018 at 16:40
  • $\begingroup$ So should not the description of the astrobiology tag be extended with "life not native to Earth" to avoid confusion ? $\endgroup$
    – Cornelis
    Oct 11, 2018 at 17:07
  • 1
    $\begingroup$ @Conelisinspace Perhaps, but I think there's a reason even scholarly sources often leave this ambiguous. It may be because we haven't really ruled out the possibility of some form of panspermia yet, though Earth-based abiogenesis is the preferred theory. It is good science to say "How can life exist beyond Earth?" rather than "How can foreign life exist beyond Earth?" because the former does not bias toward a certain outcome (namely, that life on other planets necessarily does not share a common origin with Earth life). $\endgroup$
    – called2voyage Mod
    Oct 11, 2018 at 17:16

The study of life outside of our own biosphere can be divided into three categories:

  1. Life not native to Earth. I would call this "exobiology". We haven't discovered it yet, so it is entirely theoretical and shouldn't (yet) have a tag.

  2. Life native to Earth, surviving in an environment not like Earth. Tardigrades, bacteria, and other species studied in the vacuum of space would all be examples.

  3. Life native to Earth, surviving in an Earth-like environment. This is just simply regular life-support, or terraforming.

The reason we study #2 in the first place is that is gives us many clues about the possibility of #1. Also, should #1 even exist, the chances are far greater that it is in a non-Earth-like environment than an Earth-like environment. Therefore, I would define astrobiology as

The existence or survival of life in an environment that is not like Earth.

which would cover #1 and #2.

  • $\begingroup$ Is gravity part of the environment? In other words, would questions about bone density or muscle loss or blurred vision on the ISS be tagged with astrobiology? Or are those not "existence or survival" questions? I'm thinking that a set of examples might be a helpful way to further define this particular tag. $\endgroup$
    – uhoh
    Oct 21, 2018 at 12:30
  • $\begingroup$ @uhoh: I would count that as "space medicine", a different field. $\endgroup$
    – DrSheldon
    Oct 21, 2018 at 15:38
  • $\begingroup$ Right, me too. And so your current definition is not sufficient as it does not clearly exclude space medicine. It would be great if you could extend it to help come up with a good definition for our tag here. It's a tough problem. $\endgroup$
    – uhoh
    Oct 21, 2018 at 15:44
  • $\begingroup$ "...in an environment that is chemically or biologically distinct from Earth's environment." Let me know if this revision includes or excludes too much. $\endgroup$
    – DrSheldon
    Oct 21, 2018 at 15:58
  • $\begingroup$ I don't know, perhaps other's can add comments and/or vote. $\endgroup$
    – uhoh
    Oct 21, 2018 at 16:38

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