Aerogel: The Strange Solid That's Mostly Air
A Cloud You Can Hold
Invented on a dare in the 1930s and nicknamed “frozen smoke,” aerogel is finding new uses everywhere from space missions to winter jackets.
Imagine a material that’s almost lighter than a feather – so light it’s 99.8% air – yet solid enough to support a brick. It looks like a piece of ghostly blue smoke, but you can hold it in your hand. This isn’t science fiction; it’s aerogel, the world’s lightest solid. Aerogel earned the nickname “frozen smoke” for its wispy appearance, and for a time it even held the Guinness World Record for lowest-density solid. Despite being mostly air, aerogel can be remarkably strong and an excellent insulator. In fact, it can protect a flower from the heat of a flame – a visual demo that has captivated many observers. What started as a laboratory curiosity is now a material with out-of-this-world applications (literally – NASA has used it in space), as well as down-to-earth uses here at home.
From a 1930s Bet to “Frozen Smoke”
Aerogel’s story begins in the 1930s with a chemist named Samuel Stephens Kistler. Legend has it that Kistler made a bet with a colleague, Charles Learned, to see if he could remove the liquid from a jelly without shrinking the jelly’s structure. In 1931, Kistler succeeded – he found a way to replace the liquid in a gel with air, creating the first aerogel. He published the feat in a 1931 Nature paper, describing a process called supercritical drying. Essentially, Kistler took a wet silica gel and carefully dried it under high temperature and pressure until the liquid became a supercritical fluid (neither purely liquid nor gas) and could be drawn off without the gel collapsing. The result was a solid network of silica with pores filled with air – the original silica aerogel.
Kistler’s airy invention was remarkable, but it didn’t take the world by storm right away. Making aerogel proved difficult and expensive in those early days. The process required high pressure vessels, careful handling of flammable solvents, and it even carried explosion risks – not very practical for mass production in the 1930s. Early aerogels were also slightly cloudy and not as thermally insulating as later versions, so commercial interest was limited. For a few decades, aerogel was largely forgotten, and Kistler moved on to other work.
Aerogel got a second life starting in the 1980s. Scientists (including a team in France) developed safer, more efficient methods to make aerogels. New formulas and techniques made it easier to produce aerogels in usable forms, sparking renewed interest in this unusual material. Companies and labs began exploring aerogels made not just from silica (essentially glass) but also from other substances: alumina, chromia, carbon, and even polymers. By the 1990s and 2000s, aerogel was back – and ready for real-world applications.
How to Make “Solid Air”
How do you actually create a solid that’s mostly air? The secret lies in making a gel and then removing the liquid without collapsing the structure. It starts with a wet gel – imagine a stiff Jell-O, where a solid microscopic framework is filled with liquid. To turn this into an aerogel, you extract the liquid from the gel and replace it with air. But you can’t just let it evaporate normally, because as the liquid dries, capillary forces would pull the tiny solid strands together and cause the gel to shrivel up. Instead, scientists use Kistler’s trick: supercritical drying.
In supercritical drying, the gel is placed in a special chamber and heated under high pressure until the liquid goes into a supercritical state (a phase where liquid and gas properties blur together). In this state, the liquid can be removed without surface tension forces ripping the gel’s structure apart. Then, the pressure is slowly released, and the supercritical fluid escapes as gas, leaving behind the dry, porous solid. What’s left is an aerogel: essentially the skeleton of the original gel, but with air in all the pores instead of liquid. The process is a bit like drying a sponge from the inside out so that it doesn’t shrink – except the sponge here is made of nanoscale silica strands.
Originally, aerogels were made from silica (silicon dioxide, the same ingredient as glass). Classic silica aerogel is stiff, brittle, and looks like translucent frozen smoke. These silica aerogels can feel a bit like fragile Styrofoam to the touch. Over time, researchers have developed other types: polymer-based aerogels (which can be more flexible like a foam) and carbon aerogels (made from organic gels and carbonized, useful for electronics). But no matter the material, the general idea is the same – create a porous solid network and fill it with air. An aerogel can be incredibly porous: typically 90–99% of its volume is empty space. This extreme porosity is why aerogels are so lightweight and such good insulators.
Aerogel in Action Today
After decades as a lab oddity, aerogel is now being used in a variety of cool and clever ways. Its unique combination of being ultralight, strong, and thermally insulating makes it useful in everything from spacecraft to jackets. Here are just a few of aerogel’s current applications:
Space exploration: Aerogel earned its space cred in 2004 when NASA’s Stardust probe used blocks of aerogel to collect comet dust in space. The probe was equipped with a tennis-racket-sized tray holding aerogel blocks, which allowed it to “soft catch” tiny particles from a comet’s tail without destroying them. High-speed dust that would vaporize on impact with a solid hit the air-filled aerogel and gently embedded in it, intact. In 2006, Stardust returned to Earth with aerogel trays full of comet and interstellar dust – a real-world sci-fi moment. Aerogel also helped the Mars rovers: NASA padded sections of the Spirit and Opportunity rovers with aerogel for insulation, protecting instruments from Mars’ harsh temperatures. Even astronauts benefit – NASA has used aerogel in space suit components to help insulate astronauts in space.
Super insulation for buildings and industry: One of aerogel’s most popular uses on Earth is as an insulating material. Because aerogel almost completely blocks heat conduction and convection (it’s mostly trapped air, after all), it’s an outstanding thermal insulator. Companies now produce aerogel in forms like blankets and boards that can be fitted into homes, pipelines, and appliances to improve energy efficiency. For example, fiber-reinforced aerogel insulation boards can provide the same insulation as traditional materials in half the thickness. This is especially useful for retrofitting old buildings or insulating in tight spaces where bulky fiberglass won’t do. There are also skylights and translucent panels infused with aerogel granules, which let light in but keep heat (or cold) out. In industry, aerogel insulation is used to wrap pipes, line ovens, and even insulate cryogenic (ultra-cold) storage tanks. Wherever you need big thermal performance in a slim, lightweight package, aerogel is finding a role.
Protective clothing and gear: Aerogel’s insulation power is also literally wearable. By the early 2000s, manufacturers found ways to combine silica aerogel with fibers to create flexible aerogel blankets. Now these thin blankets are used in extreme-weather outdoor gear. For instance, mountaineering jackets, winter boots, and gloves have been made with aerogel layers to keep body heat in without bulky padding. (Some winter gloves marketed as “NASA-inspired” use aerogel to stay warm but thin.) One company even sells aerogel insoles (“Toasty Feet”) to put in your boots – they’ll keep your toes cozy hiking in snow or even trekking up Everest. The U.S. Navy tested aerogel-lined diving suits to protect divers from icy waters, and NASA’s rocket scientists have put aerogel in space suit gloves to keep astronauts comfortable during spacewalks. Imagine a superlight winter coat that keeps you warm at −50 °C — that’s the promise of aerogel-enhanced apparel.
Sports and other uses: Even the sports world has dipped into aerogel. Tennis racket maker Dunlop introduced rackets with aerogel in the frame, taking advantage of its strength-to-weight boost. The aerogel-reinforced rackets could be lighter without sacrificing stiffness, giving players a potentially faster swing. Researchers have also experimented with aerogel in bicycle tires and other equipment where weight savings are critical. Beyond sports, aerogels pop up in some unexpected places. They can act as super sorbents to clean up oil spills – the aerogel can absorb lots of oil but repels water. They are used in labs as components of particle physics detectors (because aerogel can slow down high-speed particles for measurement). And in cosmetics and paints, tiny amounts of silica aerogel can serve as thickening agents or matteifiers. New ideas for using aerogel are bubbling up all the time as this once-mysterious material becomes more available.
A flower sits on a piece of silica aerogel above a Bunsen burner flame – and doesn’t catch fire. The aerogel is such a poor heat conductor that it protects the flower from the flame below. Aerogel’s incredible insulating ability is one reason it’s used in everything from house insulation to space suit gloves.
The Future: From Wearables to Clean Energy
Aerogel is impressive today, but the future looks even more exciting as scientists and engineers find new ways to exploit this material’s peculiar properties. Here are a few emerging and future uses of aerogel that have researchers and tech-watchers buzzing:
Wearable tech and electronics: Tomorrow’s gadgets and garments might incorporate aerogel to keep them light and efficient. We’re already seeing the first steps – thin aerogel sheets in jackets and shoes – but future wearable technology could take this further. Think of flexible aerogel padding in smart clothing that keeps you at a comfortable temperature, or ultralight insulating cases that prevent your phone or laptop from overheating. Researchers are even exploring aerogel-based wearable sensors and electronics, since some aerogels (like certain carbon or polymer aerogels) can be made electrically conductive yet remain soft and elastic. These could lead to breathable “e-skin” devices or health monitors that you barely feel on your body. In short, aerogel might help tech disappear into our clothes and surroundings, by making advanced components nearly weightless and invisible.
Building the cities of tomorrow: In construction, aerogel is poised to play a bigger role in making buildings more energy-efficient. Insulation boards and plasters with aerogel are already letting architects super-insulate walls and roofs without enormous bulk, and future building codes could embrace these high-performance materials as their costs come down. Beyond just panels, innovators are mixing aerogel into concrete and other composites to create structural materials that insulate as well as support. Imagine aerogel-infused concrete that makes a house both strong and thermally snug – your walls could be much thinner but lose far less heat. Windows might be made with aerogel between glass layers, allowing light while blocking heat. Some designers even envision aerogel in paint or thin coatings that could turn any surface into an insulator. As cities push for green building solutions, aerogel’s ability to save energy is a big draw. The challenge, for now, is cost – aerogel products are pricier than conventional insulation. However, production is ramping up worldwide, which should drive prices down. Industry analysts forecast a boost in adoption of aerogels for construction and other insulation uses as manufacturing scales up in the coming decade.
Revolutionizing batteries and energy storage: One of the hottest emerging markets for aerogel is in electric vehicles (EVs) and batteries. Automakers and battery makers have discovered that thin aerogel blankets make excellent safety barriers around battery cells. These aerogel liners are superb at resisting heat and flames, so they can prevent a chain reaction known as thermal runaway (when one overheating battery cell causes its neighbors to overheat). By inserting feather-light aerogel insulators between cells, EV designers add crucial fire protection without much weight. This is becoming so important that aerogel use in EV batteries has exploded nearly 20-fold from 2021 to 2024. Major car companies in Asia, Europe, and the U.S. are adopting aerogel for battery safety in upcoming models. In the future, if you buy an electric car, there’s a good chance it will have aerogel guarding its battery pack – potentially saving lives and property by reducing fire risks.
Aerogels are also being explored inside the batteries themselves. For example, carbon aerogels can serve as electrodes or supercapacitor elements. Because aerogels have such a huge internal surface area in a tiny volume, a battery or capacitor made with aerogel can store a lot of charge in a very small package. Researchers have built aerogel-based supercapacitors that are thousands of times smaller than standard capacitors with similar capacity. This could mean future electronics (or electric cars) with lighter, more compact energy storage. And since aerogel materials can be designed to be conductive, they might be used as lightweight current collectors or support structures in batteries, possibly leading to faster-charging and longer-lasting cells. While these technologies are still in the lab, progress is steady, and we may see aerogel-boosted batteries in the next generation of electronics and renewable energy systems.
New frontiers: Beyond the big three of wearables, construction, and batteries, aerogels are finding all sorts of futuristic uses. Scientists are testing aerogel materials for water purification, like special aerogels (so-called “chalcogels”) that can absorb toxic heavy metals from water. Environmental engineers are looking at aerogel substrates to clean up pollution by soaking up oil or chemicals, then being recovered and reused. In aerospace, the push for lighter materials never stops – and here polymer-based aerogels that are stronger and more flexible could lighten everything from airplanes to spacecraft. For instance, prototype drone aircraft have used aerogel insulation to protect sensitive components without weighing the drone down. NASA is investigating aerogels for future missions as well, such as insulating habitats on the Moon or Mars, where every pound of material is precious. And materials scientists are continually tweaking aerogel recipes, sometimes inspired by nature (one recent experiment mimicked dragonfly wings to create a new aerogel drying method). These advances could yield aerogels that are cheaper, more robust, or tailored to specific tasks like soundproofing or even electromagnetic shielding.
Looking ahead, aerogel’s biggest obstacle to everyday use has been its cost – making airy super-material isn’t cheap. But with demand rising and production methods improving, the price is gradually coming down. Aspen Aerogels, one leading manufacturer, now produces millions of square feet of aerogel material per year and has been scaling up output to meet the needs of industries like EV batteries and construction. As manufacturing ramps up, experts predict aerogel will become more accessible and find its way into more products. We may not be far from a future where “frozen smoke” insulates your home, powers your gadgets, and even keeps your coffee hot, all while being almost invisible due to its slim, lightweight form. Aerogel’s journey from a 1930s bet to a cutting-edge material shows how a quirky idea can take time to shine – but it’s now clear that this light-as-air solid has a very solid place in the technology of tomorrow.
The Stardust spacecraft’s dust collector, filled with blocks of blue aerogel in a metal grid, was used to capture tiny comet particles in 2004. The aerogel’s low density let it “soft-catch” cosmic dust: particles flying at 6 km/s burrowed into the aerogel and were gently trapped, rather than shattering on impact. This successful use of aerogel opened the door to many other space and scientific applications.
Sources
J. Heber, “May 1931: Publication of the Creation of the First Aerogel,” APS News (May 16, 2021)
Wikipedia: “Aerogel.” Wikipedia (accessed Jul. 2025)
A. Green, “How The Aerogels Market Will Evolve Over The Next Decade,” IDTechEx (Oct. 2024)
NASA – Stardust Mission: “Aerogel: Capturing Comet Dust” (NASA Science, 2014)
M. Ayers, “The Pioneer: Samuel Kistler,” Lawrence Berkeley Lab (May 2000)
Kiddle Encyclopedia: “Aerogel Facts for Kids” (2025)
Wikipedia: “File:Aerogelflower.jpg” (NASA/JPL, public domain image).
Wikipedia: “File:Stardust Dust Collector with aerogel.jpg” (NASA, public domain image).
