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Graphene would be a great material to build a rocket out of. Graphene is extremely thin. One single atom thin layer of graphene can withstand 15 000 000 pascal . A square meter of this material only weighs 0.77 milligrams. So why doesn’t NASA use it for their rockets? I would think that if they had such a light material that can withstand so much, it would be used for spaceflight.

Sources:

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    $\begingroup$ Actual requirements may include tension, compression, shear, fatigue resistance, etc. One parameter does not a structural material make. $\endgroup$
    – Jon Custer
    May 10 at 14:13
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    $\begingroup$ Add price to the list. $\endgroup$
    – SF.
    May 10 at 14:43
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    $\begingroup$ @GdD Almost every article I read on the potential wonders of graphene is couched with words such as "could" and "might". It appears that graphene is not yet living up to its potential wonders. $\endgroup$ May 10 at 15:38
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    $\begingroup$ A square meter of this material would weigh 0,77 milligrams, but we are very far from producing a full square meter as a a single contiguous sheet. $\endgroup$
    – Uwe
    May 10 at 17:13
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    $\begingroup$ Because NASA is saving their graphene supply for the space elevator, of course :) $\endgroup$ May 11 at 3:38

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The Technology Readiness Level (TRL) of graphene is at 2 or 3 as far as I can tell. And that is TRL as related to making very tiny stuff.

Anything used to build a structure for aircraft or spacecraft must be at TRL 8/9 and highly characterized in that specific application (a large database of statistical evidence of performance over a large range of operational parameters).

Graphene as a structural material is still a pipe dream. This says nothing about the insane costs graphene would entail.

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    $\begingroup$ @BradV - please go back and read our code of conduct. Your behaviour is not what we expect to see here. Others have tried to help you improve your post so that it is of more value to future visitors - as is expressly encouraged on Stack Exchange. space.stackexchange.com/conduct $\endgroup$
    – Rory Alsop
    May 13 at 7:34
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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Rory Alsop
    May 13 at 7:35
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Besides the fact BradV pointed out that we don't have the technology to do this yet, the fact is that graphene on a macroscopic scale would not perform as well as the numbers you cited suggest. All the results indicating insane strengths for graphene are done on a tiny, tiny scale. Bulk materials are always much weaker, because the slightest imperfection is a place where force is concentrated by huge factors.

Graphene will eventually be valuable as a bulk material, I believe, but it won't be as magical as the quoted numbers indicate.

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    $\begingroup$ Also, depending on exactly what properties you are measuring, it is likely that the square-cube law will make bulk materials worse simply because they are larger. $\endgroup$
    – Kevin
    May 11 at 17:56
  • $\begingroup$ @Kevin well that's why materials are compared using intensive properties instead of extensive ones $\endgroup$
    – user253751
    May 12 at 12:52
  • $\begingroup$ @user253751: It nevertheless remains the case that scaling things up is hard and the square-cube law is a major reason for that difficulty. $\endgroup$
    – Kevin
    May 12 at 17:50
  • $\begingroup$ @Kevin ... that's why materials are compared using intensive properties. Scaling things up is the same difficulty for every material. We know how to calculate how much more material you need when you make it bigger. If graphene is stronger than steel (let's say) then a graphene rocket needs to use less graphene than a steel rocket uses steel, full stop. $\endgroup$
    – user253751
    May 13 at 9:59
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    $\begingroup$ @Kevin you are fully correct that graphene is stronger than steel. It is actually 200 times stronger than steel according to this site science.howstuffworks.com/innovation/new-inventions/… $\endgroup$ May 14 at 10:48
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Many processes being used to make graphene only yield small and irregularly shaped flakes with a lot of defects. The size of those flakes is barely enough to render them visible for the naked eye, and that is nowhere near what would be required to build a whole vehicle.

Graphene as a miracle construction material is overhyped in a similar manner to supercapacitors being overhyped as a miracle alternative for batteries. However, we haven't seen any supposed miracles outside of the sketching boards yet.

While pure, large, monolithic graphene sheets remain in the realm of fantasy for now, small and irregularly shaped graphene flakes have their own utility in the context of engineering of materials, as they could be used as a strengthening additive in composite materials. For example, one kilogram of cement can be made 30% stronger by mixing in just one gram of flash graphene flakes (here is the source, which in general talks about the method of obtaining flash graphene from organic materials, like coffee grounds).

In this thread one can find information about how composite materials in general (but not specifically graphene-based ones) are currently being used in rocket construction, and why in most scenarios they are inferior to metals. In short, structures constituting a rocket have to withstand extreme thermal stress, extreme temperature swings, and be resistant to radiation. Composites aren't fulfilling those requirements.

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Just because a substance has impressive specific strength, doesn't mean it has all the properties needed to make it generally useful.

Specific strength, the ratio of strength to weight, is a very important figure of merit for a material since it determines a number of theoretical limits. However, this totally fails to take into account other neccessary properties for a material suitable for more general use. A material should typically also be rigid, be practical to apply loads to evenly, not be subject to fatigue or hidden cracks, not be brittle or subject to catastrophic failure, and should have strength in the directions desired which depends on the application, but always some strength in each direction is desired for rigid components.

A material also needs to be affordable both to produce and to form or machine to the desired shape, and be resistant to the environmental conditions it will experience. While space programs expect and operate with large budgets, they do want to choose a less expensive option even if it is technically not the "best" one.

Ductile metals (steel, aluminum, titanium, etc) have many of the above desired features as well as fairly good specific strength, so they are extremely popular. Historically, the useful advance has often been fabrication techniques rather than fundamental materials, such as careful machining or 3D printing that allows a large, complex part to be made of a single piece of material with skins, structural members, and mounting brackets all combined and no wasted weight.

The Aerospace world is very conservative, even the mavericks like SpaceX.

Simply put, the world of aerospace engineering does not react to trends in technology very quickly at all, and especially not at the rate of hype and rumor. Aerospace projects often take years from beginning of design to completion, and safety concerns and the need for very expensive projects to succeed the first time mean that if an old technology works, a new technology will only be used if it provides a huge benefit or makes something possible or economically feasible that wasn't before.

While SpaceX has been less conservative in a number of respects than the "old guard" aerospace contractors and space agency staff who have historically designed rockets, that doesn't mean they aren't bound by the same conservatism for the same reasons, and moreover SpaceX has often followed the principle of using inexpensive, simple technology where possible to save costs -- for example, making Starship out of ordinary high strength stainless steel.

We're Kind Of Already Using It

Graphene refers to a single sheet of the graphite crystal. Carbon fiber, such as is used in carbon fiber composites, is made of carbon. Depending on the type of carbon fiber, a significant portion of the carbon is indeed in the form of graphene! While carbon fiber composites are a pretty good material and are used in a number of aerospace applications, they have limitations that mean they aren't particularly heavily used in space. Notably, Rocket Lab's Electron uses carbon fiber composite for the main body of the rocket.

Super-Specific-Strength materials tend to be specialized

Looking at Wikipedia's list of materials by specific strength, the highest specific strength materials (higher than ductile metals) listed include mostly:

  • Fibrous materials, which will only produce cloth or rope by themselves (and whose strength is fundamentally tied to their fibrous form)
  • Nanostructures that don't necessarily reflect a practical bulk material
  • A wood that, while very strong and light, resembles styrofoam in its fragility and crushability.

Graphene is a fad (for right now)

Graphene has recently been developed to a form where lots of experimental applications can be tested, but people haven't yet figured out what it is good for in a really practical sense. This is accompanied with a great deal of hype. This is far from new: I remember when carbon nanotubes were the big thing, and occupied roughly the same position in hype. Hopes of space elevators and similar super-engineering were much depressed over time as nobody really succeeded in bonding individual carbon nanotubes into a rope or yarn with strength matching that of the individual tubes.

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  • $\begingroup$ The other thing that could be added to this is all materials are stronger when their dimensions are minute due to reduced numbers of atomic dislocations within the matrix of the material. As the material's dimensions increase the number of dislocations increases reducing it's strength properties. Graphene may have impressive strength properties for minute pieces of graphene, but that does not mean it will have such properties should we ever be able to make graphene in larger sizes. $\endgroup$
    – Fred
    May 15 at 8:49
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    $\begingroup$ This comment isn't fully correct. We have found out what graphene is good for in a practical sense. Batteries is one out of many examples that graphene can be used for. If you read through the links I have sent in my question then you will find more examples and other things. I think you should read a bit before making an answer. I would recommend this site here nanowerk.com/what_is_graphene.php for more information $\endgroup$ May 15 at 10:40
  • $\begingroup$ this answer from ikrase does a fine job spelling out a lot of the factors that go into materials selection for product design. One particular passage stands out to me and bears repeating. ikrase wrote "While space programs expect and operate with large budgets, they do want to choose a less expensive option even if it is technically not the "best" one." I am very familiar product design and have operated in the world of "SWaP-C" which stands for Size, Weight and Power (and) Cost. $\endgroup$
    – BradV
    May 15 at 13:19
  • $\begingroup$ Here is where I was going with this... Another addition to the acronym SWaP-C should be T for timeline. A design team may have a totally great overall solution that meets ALL requirements and is much better than all other solutions. However, this solution would be worthless if it took too long to implement. $\endgroup$
    – BradV
    May 15 at 13:26
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Because it is carbon with high reactivity. It burns at fairly low temperatures in the presence of oxygen: "Graphene combusts at 620 K." Supersonic skin would burn up. Descending through its own exhaust plume would incinerate a returning stage, etc.

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    $\begingroup$ Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. $\endgroup$
    – Community Bot
    May 12 at 17:17
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    $\begingroup$ Just to make it clear this here was James first post. Be friendly and kind. $\endgroup$ May 13 at 4:46
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    $\begingroup$ I edited and provided a source. I assume that there are more downsides to graphene: How do its mechanical properties change when very hot or very cold, as happens in a vacuum? How does it cope with lateral loads -- does it crack like my carbon fiber bicycle frame? Etc. But I have no time right now to do an in-depth research. $\endgroup$ May 13 at 11:58
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    $\begingroup$ Plenty of useful materials, such as some composites and aluminum, have similar temperature limitations. $\endgroup$
    – ikrase
    May 15 at 5:33

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