If a product was to be made for use in space, there may be certain materials or certain combinations of materials that might work well on Earth, but be particularly unsuitable for spaceflight applications.

One example that comes to mind are the protein cubes or bars described in the Andy Weir Novel The Martian and to a lesser extent in the film adaptation of the same name, where the simultaneous combination of high G-force and vibration caused the material to dramatically change it's mechanical properties. The phenomenon is described further in Quora and a KSP forum.

So materials that turn to goop during launch (and I mean the protein in cube form, not human form) are automatically out as a class.

But are there others that turn out to be handy on Earth but unsuitable (and especially those that might be unexpectedly so) in spaceflight, so that they would fail either during a cargo delivery or while in microgravity in a commonly used space environment for astronauts?

  • 1
    $\begingroup$ This question is too broad as it stands. What do you mean "best"? What purpose is the material serving? Both of those make a large difference. $\endgroup$
    – PearsonArtPhoto
    Commented Feb 27, 2018 at 10:43
  • $\begingroup$ There is no single best material. A combination of several materials has to be used. For each problem the optimal material has to be chosen. $\endgroup$
    – Uwe
    Commented Feb 27, 2018 at 10:49
  • $\begingroup$ I've substantially rewritten your question, but I think it is now more suited for the Stack Exchange environment. You are welcome to roll-back if you don't like it (click the "edited" indicator and then look for roll back). You can also see how this flies and then ask additional questions. For background information on the site, you can take the tour and visit the help center especially the part Types of questions to avoid asking?. Welcome to Stack Exchange! $\endgroup$
    – uhoh
    Commented Feb 27, 2018 at 15:47
  • $\begingroup$ Gallium's not common, but try getting within 30 ft of a plane with some, much less a launch vehicle $\endgroup$ Commented Sep 10, 2021 at 15:09

2 Answers 2


Any material that outgasses should not be used in a spacecraft. Though this could be a lesser problem for human-flight within a controlled atmosphere.

Any material that is prone to whiskers in soldering also needs to be avoided.

One example that comes to mind is cadmium, which was prohibited in some NASA standards.

Another common complaint is about titanium, which allegedly does not disintegrate in the atmosphere, thus being dangerous to use.

This provides a starting basis for some materials that are banned for space applications. As to what is a good material, that would be a case-by-basis and application-specific analysis.

  • $\begingroup$ Cadmium would be a no-go anyway, because it's hideously toxic. $\endgroup$
    – Vikki
    Commented Sep 9, 2021 at 4:08
  • $\begingroup$ @Vikki : So is hydrazine, but most satellites with propulsion use it. The question is not restricted to manned spaceflight. $\endgroup$
    – Mefitico
    Commented Sep 9, 2021 at 12:41

Granular salt and pepper are not suited for use in free fall because the grains can readily escape and get in crewpersons's eyes and/or nostrils.

To get around this

Polyethylene dropper bottles contain bulk supplies of liquid pepper and liquid salt. The pepper is suspended in oil and the salt is dissolved in water.

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image source

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    $\begingroup$ as is pointed out here as well. $\endgroup$
    – uhoh
    Commented Oct 17, 2020 at 10:17

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