There is at least one question, which really bugs me: How hard is the Lunar surface?

Yes, this is science. Yes, it is planetary science. Yes, it is about space instruments, landings, engineering, data, modelling, understanding space objects and space exploration in the first place. I have a hard time to understand, that there could be a difference between science and exploration. For me, this is awkward and strange. Could someone explain to me, where there could possibly be a boundary?

Space.SE is defined as "Beta Q&A site for spacecraft operators, scientists, engineers, and enthusiasts". I am a scientist. If you guys think that there is a boundary by any definition, I would like to propose to officially broaden the scope and include planetary sciences at the very very least.

(Actually, such stuff would make excellent questions for a geoscience stack exchange. Since there is not any and since this stuff does not fit into astronomy or physics, this is also the only place where someone could ask such a question.)

  • $\begingroup$ I thought geoscience was specific to Earth. $\endgroup$
    – AlanSE
    Aug 23, 2013 at 18:09
  • $\begingroup$ @AlanSE Traditionally, yes. Since Apollo, no. $\endgroup$
    – s-m-e
    Aug 23, 2013 at 18:24
  • 1
    $\begingroup$ I also thought other terms are used for that, e.g. "astrogeology", "exogeology" or "planetary geology"? My problem with using "geoscience" to describe Lunar science is, that it starts with "Geo" (of Gaea / Gaia, i.e. of or relating to the Earth). :O $\endgroup$
    – TildalWave
    Aug 23, 2013 at 19:02
  • 1
    $\begingroup$ @TildalWave Such terms never found broad acceptance. Terrestrial and extraterrestrial guys share journals and conferences. It is usually a traditional geoscience with an attribute (e.g. "planetary geology" or "geochemistry of minor planets"), if a distinction is made. "Geo" remains. Browse though the program of the European Geosciences Union General Assembly. There is a block for "Planetary & Solar System Sciences", but you find such contributions elsewhere in the meeting, too. (EGU is by far the largest European geosciences meeting.) $\endgroup$
    – s-m-e
    Aug 23, 2013 at 20:19
  • $\begingroup$ @ernestopheles - I'll take your word for it. I just didn't know, that's all. I've never been involved with geology anyway (spelunking doesn't really count), only with geodesy. ;) $\endgroup$
    – TildalWave
    Aug 23, 2013 at 21:15
  • $\begingroup$ There is a Geoscience proposal in Area 51, currently in the commitment phase. $\endgroup$
    – user838
    Oct 4, 2013 at 14:25

2 Answers 2


I'll bite: advancement of planetary science is currently the main goal of space exploration. Thus, on-topic at SEx.SE.



  • questions about lithosphere, atmosphere, hydro/cryosphere, ionosphere of Solar System bodies, if these questions can be answered with current or near future technology (regardless of where the scientific equipment is - down here on the Earth, in LEO, in orbit around the body, or on the ground).

  • questions and answers that describe engineering considerations of concrete technologies used to solve planetary science puzzles

  • planetary geography questions

  • paleogeology questions for Solar System bodies that have been answered or can be practically answered in the near future (sigh - near $\approx$ 50 years with the current levels of funding)


  • speculative questions about exo-solar planets (until we have the technical means to narrow down the list of competing hypotheses)
  • questions about exoplanets that can be answered by Astronomy SE folks with the current methods of investigation ("How do we know this planet is a hot jupiter?")
  • questions about Terran geology/atmosphere/hydrosphere insofar they don't relate to exploration of other Solar System bodies (there's an Earth Science SE for that)
  • questions that require in-depth discussion of physics involved without touching upon practical engineering issues (migratable to Physics.SE)
  • questions about relativistic phenomena unless relevant for spaceflight (Physics SE fodder once again)
  • $\begingroup$ I do not mind speculative questions as long as the answers are not speculative. Specifically in terms of exoplanets, it is surprising how far you can stretch current data into interesting results. So it is always worth looking for current papers on the topic in depth before shutting down such questions right at the start ... $\endgroup$
    – s-m-e
    Aug 23, 2013 at 20:46
  • $\begingroup$ @ernestopheles - agree with you on the need for voters to be knowledgeable about the stuff. A lot of exoplanet evidence can have several equally valid interpretations, so I'd better relegate such discussions to Physics.SE. $\endgroup$ Aug 23, 2013 at 20:50

Well, what other questions are we supposed to have? Rocket science, artificial satellites, and their operation? Good, but what purpose would they serve, if not gathering data on the Earth, the Sun, the Moon, and all other celestial bodies, their interactions, and prospects for our use of them to our advantage, beyond merely observing shiny object twinkling on the night's sky?

Planets, asteroids, comets, stars, e.t.c., their interactions, our ability to study them, interpret gathered data, build physical models to which we can test our equipment for further exploration of them, or use of them to explore others. To better our understanding of our celestial neighborhood, protect ourselves from dangers they pose to us, use their resources to our advantage, and build better performing, safer, longer lasting, cheaper,... equipment, procedures, and anything else relating to humankind's space exploration. That, and a lot more even, cannot possibly be irrelevant to space exploration, can it?

Count this answer as agreeing, that a question about the hardness of the Lunar surface is on topic.

If we're to use the Moon to our advantage, be it to mine it for resources, plan future landings there, send surface penetrating probes, use seismographs (which we do), drill (which we did), collect rocks (which we did) and later wonder where they came from, or use it as a low gravity platform to reach other celestial bodies cheaper and faster, maybe even produce the needed rocket fuel there, all of these endeavours will be asking this "how hard is the surface" question, and they'll need an answer.


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