We know a lot of elements and metals to make spacecraft out of. We also tried many options regarding so to make spaceflight as safe and inexpensive as possible. It is not often we find a material that completely revolutionises the way we see space exploration - one that could change everything.
This material is not one but many, and they are called nanomaterials. Nanomaterials are materials with at least one dimension in the 1 to 100 nanometer range, which is extremely, extremely small. This size gives these materials unique properties different from their normal-sized counterparts.
Launching anything into space is really expensive. That’s why shaving off even a single gram can save you thousands of dollars. Even the most efficient, reusable, and most used rocket, SpaceX’s Falcon 9, costs 2,720 USD to launch a single kilogram into orbit. If you make the object you are launching lighter, you save thousands, or you can fit more payload for the same price.
That’s where nanomaterials come in. They are extremely light, without any sacrifices to their strength. That makes them the ideal contender for spacecraft design. Examples of such materials are carbon nanotubes or graphene. They serve as the main material the spacecraft is made of, making it clearly superior to its counterparts. Let’s say you wanted to launch a perfect cube of stainless steel weighing precisely 1 kilogram into space. The same volume of graphene would only weigh 281 grams. And now the most surprising part – if you count by Ultimate Tensile Strength (UTS), graphene is around 325 times stronger than steel. If you measure by stiffness, graphene is 5 times stronger.
That’s why they are currently being used (although in only a few) in satellites, rockets or space stations.
But sometimes, steel cubes aren’t the object being launched – humans are. And if you get high enough above the surface, Earth’s magnetosphere protection is out of the equation, and our modern spacesuits cannot safely protect humans outside of their spacecraft.
However, nanomaterials can help with that too. They can very effectively protect from radiation, whilst being as light and strong as previously mentioned. They can be added into spacesuits, making them more radiation resistant and lighter too.
They are also being used on space stations (most notably on the ISS) as near-perfect water filters. Their microscopic size makes it possible to capture an incredibly large spectrum of debris – anything from bacteria and viruses to remains of medicine or heavy metals.
Their radiation resistance may also hint at their thermal capabilities, as they are truly very heat resistant. They can be added into rocket engine nozzles or any part that is exposed to extremely high temperatures (1,500 degrees Celsius and more) to make them more resistant. With rockets’ first stages becoming slowly more and more reusable, having engines that are capable of being reused as well is beneficial. Nanomaterials might help with that.
They can also be added into rocket fuels for a more complete and faster reaction. Their incredible surface-to-volume ratio makes them perfect for this task. Nano-aluminium or nano-boron particles are being added into fuel mixtures.
We’ve also seen mini-satellites (such as the CubeSat) popping up more often. They would not be possible without these materials. Their body has to be incredibly light but also endure the harsh environment of space. Their electronics have to be incredibly tiny (more on that later), and their batteries can be more efficient with nanomaterials.
Electronics are getting smaller and smaller. We have now reached a point where processors have entered the nano worlds. Transistors are so small we cannot even comprehend it. We can also use them to make sensors so sensitive that they can detect single molecules or incredibly low levels of radiation. These are key for extraplanetary exploration.
Ultimately, nanomaterials have one more ability that is specific to them. Imagine all the debris that is in orbit (or don’t imagine and see SNW #44: All you need to know about Space Debris) flying around at very high speeds. This is what a 14-gram piece of space debris can do to a block of solid aluminium.
You can forget that you need to be going a certain speed to remain in orbit, and if two objects with this velocity collide, it can be a real problem. Luckily, nanomaterials can (as with everything mentioned here) help with that. Small cracks or holes can appear on the exterior of spacecraft or space stations due to these small particles. Normally, that would take an astronaut outside with all his tools for multiple hours – and that’s the best-case scenario aboard the ISS, where repairs are possible. If it weren’t for nanomaterials, the damage would be stuck there.
When a crack forms, the impact from the collision breaks the material itself but also tiny nano-capsules embedded into the material. These capsules contain a healing agent (usually polymer) that will heal the damage caused by the impact. This is a one-time-only solution, and it will only work for small cracks, but it is better than nothing.
As we can see, nanomaterials have loads of benefits. They seem like the best solution to each problem regarding space. They have only one downside, though, and that is their price. They are way more pricey than standardly used materials, which makes them a latter choice for spacecraft designers. But can we somehow make them cheaper? Is it possible to see a future where nanomaterials play such a key role in space exploration that we cannot imagine it without them? We can only wait and see.
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