Question: What material are rockets made out of?

Alessio Spampinato answered on 11 Oct 2022: last edited 11 Oct 2022 11:13 am

This is an interesting question. In a rocket (and in general in spacecraft) we can use many different materials. Typically, we use titanium, aluminium and even stainless steel. It depends a lot on the particular application of the component you want to make, like highest/lowest temperature or if it is meant to resist to high pressures (like a fuel tank).

In general, if you need something capable to resist the mechanical loads associated with a launch into space, you want to make sure you use the right material for the right level of stress. For instance, titanium is great as it is very strong and light in comparison with other materials. However, you would do some simulations on your component and see whether you actually need to use something as strong as titanium, or if using aluminium (as an alloy) is good as well.

Then, there are considerations to make on the temperature range that component will experience in its life, plus considerations on corrosion and compatibility with the the materials making the other components it is in contact with.

Finally, apart from the metals I mentioned, nowadays we start seeing more composites materials (like ceramic matrix composites) used for space application. These are great, as they can be quite light and strong. However, they might have some issues with outgassing (this is the release of gas from the material when it is in vacuum, like in space) and they tend to break without any warning. To explain the latter better, a metal typically deforms under a high load and might deform enough to develop a crack and start breaking (basically it loses elasticity at first and then can’t cope anymore). With a composite material, the deformation is typically lower and a crack could develop all of a sudden, leading to an unexpected breakage.