What is the latest technology of materials for space applications? For example, what will you use to make the next generation of spacesuits? Or a spacecraft to take it to an exoplanet? For our purposes, let us avoid what is about to happen; no one wants to read information about atomizers, or the kind of unwise gimmicks that look glamorous but end up killing people. Here, we will only cover what is being used, or at least what is being beta tested in this area.

There are several different types of technological developments. Broadly speaking, the recipes and manufacturing methods we use to make new materials have evolved together, and the things we try to do with our materials have become more ambitious. We are facing greater dangers, and we must have a corresponding degree of mastery of the composition and performance of the materials used.

There are also several basic materials. Advanced composite materials layer different materials together, while alloys melt or dissolve substances together to obtain a uniform finished product.

Consider ceramics. The classic definition of ceramic is a very hard and brittle oxide, nitride or carbide material, that is to say, if you receive a large enough physical impact, it will crack. Ceramics are generally strong under compression, but weak under tensile and shear stress. But when ceramic materials are heated to be as viscous as spinning sugar and then blown into fibers through nozzles, they can be processed into soft and elastic fabrics, such as ceramic cotton, silicon felt and "flexiramics." These materials do not burn at all, so they are very useful when used in soft, shock-absorbing and flame-retardant liners.

Glass-ceramic is a little more familiar to most of us. If we change the name: Gorilla Glass, it is very common in smartphones today. It is an aluminosilicate glass formed by nucleating molten glass around ceramic dopant particles that are only soluble at high temperatures. According to Corning, when it cools, this will make your crystallinity reach between 50% and 99%. The resulting material is very similar to glass, except for its transparency. When tempered, the balance between tension and compression makes these things extremely hard. Glass-ceramics also work well with conductive coatings, and engineers use this feature on spacecraft windows to prevent them from freezing and freezing.

Spacecraft windows are an important application of materials science. One way to make windows suitable for space use is fused silica, which is 100% pure fused silica. Another crazy window material is aluminum oxynitride, which is actually the transparent ceramic we use to make bulletproof. In a video made by a manufacturer of aluminum oxynitride bulletproof products (see below), 1.6 inches of AlON is sufficient to completely block 0.50 calories of armor-piercing projectiles. AlON and fused silica were originally a fine powder called glass frit, which was compacted into a mold, and then baked into a transparent superhard material at the most incredible temperature.

Unless you use 100% pure substances (which is impossible in many cases), the idea of ​​doping is at the core of all of this. Stimulants mean adding something special to an otherwise ordinary recipe to take advantage of the benefits of special things without having to deal with the defects of its purity. In many cases, the result of doping has little resemblance to its parent material.

Metallurgy relies heavily on doping, which in this case is called alloying. We can do some very wonderful things with metal. The melting temperature of the aluminum-niobium alloy is sufficient to withstand the thermal environment in the nozzle of the Falcon 9 engine. But this is only because they also use regenerative cooling: the propellant circulates through the cavity of the nozzle wall, cooling the bell and heating the propellant. (This is a heat pump.) Alloys containing gold and brass are useful because they will not corrode, regardless of temperature or chemical extremes. Just like the anti-caking additives in Parmesan cheese, there are even metal alloys that contain silicon, because silicon makes molten metal flow more easily and is therefore more suitable for complex castings.

Friction stir welding physically melts the two materials being welded together, turning them into a structural entity, solving the joinery problem of some of SpaceX's aluminum alloy parts.

We often see new material chemistry in semiconductor research. Recently, the control of dopants has become fine enough to introduce single-atom point defects into the diamond lattice. This manufacturing precision is also important for so-called "high-entropy" alloys, which are mixed mixtures of four, five or more different elements that can greatly improve toughness and make things made from them thinner , Lighter, and more durable. A metallurgist at MIT has created a high-entropy steel-like alloy that is very hard and highly ductile. I and others believe that these properties are mutually exclusive.

Of course, the choice of dopant is very important. Tantalum and tungsten are hard, dense, and radiation resistant metals that are stirred into titanium to make Juno's "radiation bank". The vault protects the precision circuits in the scientific payload, making itself brittle, so that the electronic equipment can last as long as possible.

Radiation hazards can be mitigated by shielding—basically, place atoms between your payload and high-energy charged particles, which can flip bits, corrode metals, and short-circuit connections. Lead is an obvious choice on Earth, but lead is not suitable for space flight because it is too soft to withstand vibration, and it is too heavy to be practical under any circumstances. This is why Juno's radiation library is mainly titanium; it is stronger than aluminum and lighter than steel.

This is actually a major problem, trying to figure out how to keep electronic devices in space for as long as possible. If you don't have a computer, you can't build a spaceship. Although we continue to shrink the size of circuits and reduce their power requirements, at a certain point, there is a physical layer of size and power consumption. Around these thresholds, it is very easy to disrupt the system. Radiation damage, thermal differences, electrical short circuits, and physical vibration can all cause harm to electronic circuits. Spintronics can help advance the development of computers, provide greater computing bandwidth, and be used to perform anything that needs to be done during interstellar voyages. They can also strictly limit electromagnetic hazards, which can be so destructive to electronic devices in strong magnetic fields, such as the magnetic field around Jupiter. But before we make optical circuits or spintronics a reality, we will have to figure out how to make good old electronic devices operate in space, which may involve a good old Faraday cage.

Composite materials are difficult to produce because they usually require extremely specialized manufacturing facilities, huge autoclaves, etc. But when they are good, they are very, very good.

Multilayer Insulating Material (MLI) has both thermal and electrical insulation properties, and NASA can use this material almost anywhere. MLI makes the spacecraft look like it is covered in gold foil. But there is a kind of MLI that is suitable for applications where the entire shebang also needs to be electrically grounded. It uses a metal mesh instead of a gauze-like textile mesh between foil layers.

SpaceX uses rigid composite materials in its vehicle structure, stacking carbon fiber and metal honeycomb layers together to form a structure that is both light and strong. Foams and aerogels can also be made into lightweight, rigid, non-heat-permeable layers.

After retrieval, this is what the Falcon 9 fairing looks like. Note the carbon fiber wraps sandwiching the metal honeycomb.

Composite materials are excellent at resisting physical hazards and stress, but rigid materials are not the only way out. The BEAM inflatable capsule module, which I affectionately calls a canned bouncing castle, is made of flexible composite materials, including a unique glass fabric called beta cloth. Since the end of the 90s, NASA and other agencies have been using test cloths and similar things, and for good reason: these things cannot be scared. It is made of PTFE coated glass fiber in basket woven fabric, which is the crystallization of glass fiber and Teflon. It is almost impossible to cut or even scratch with the hardest and sharpest blade. Because it is flexible, it is shock resistant. Even if it is corroded by free atmospheric oxygen, it will not corrode. Scientists shoot it with a laser, which is why it finally begins to degrade.

Similar to the beta cloth, there is also the flexible Chromel-R metal cloth, which we use for wear-resistant patches on spacecraft fuselages and spacesuits. Chromel-R is like a woven glass mat of beta cloth, but made of hard coated metal wire. In addition, the scientists discovered that the "filled Whipple shield" is a layered candy of ceramic fiber cloth and Kevlar, which has a better effect than aluminum plating. It can prevent ultra-high-speed ceramic particles that simulate space debris by melting or decomposing the particles ( PDF).

Space suits are actually the perfect application of flexible composite materials. No single material can resist everything. But if you sandwich thin layers of several materials together, each of which can resist most things, you will get an all-purpose exterior that can still bend and bend with the wearer. Add a layer of Darlexx or similar, just like SpaceX's next-generation space suit, and cover it with a layer of flexiramic cloth, and you have a fire-resistant pressure suit. There is also a layer of non-Newtonian fluid cushioning and some ceramic alloy wound plates. Now it is a fire-resistant body armor. Then all you need is the HUD in the helmet, and possibly some high-density memory foam in the seat cushion. This is something we can do with the products available today.

Check out our ExtremeTech series of explanations for a deeper understanding of today’s hottest technical topics.

Top image source: SpaceX Dragon V2 interior

Subscribe now to send the latest ExtremeTech news directly to your inbox.

© 1996-2021 Ziff Davis, LLC. PCMag Digital Group ExtremeTech is one of the federally registered trademarks of Ziff Davis, LLC and may not be used by third parties without express permission.

We strongly recommend that you read our updated privacy policy and cookie policy.