Monday , June 14 2021

A cloud that was invented to win a bet – BBC News



Its airy appearance and lightness make it look as if someone stole a piece from one of the clouds floating in the sky.

However, it is surprisingly strong.

And that makes it perfect for catching stardust.

And because it consists mainly of air, and the air is such a terrible heat conductor, it can even protect the flower against a sharp flame.

They call it "frozen smoke" and "solid cloud"but its official name is airgel.

Challenge

An exotic transparent blue smoke substance was discovered by scientists and a chemical engineer Samuel Stephens Kistler apparently as a result of the competition with Charles Learn to see who can "replace the fluid inside the jar with jam without causing any contraction".

In 1931, Kistler published an article in the journal Nature entitled "Cohending expanded aerogels and gelatins" and continued to study the material he created.

In the early 1940s, Kistler sold the license for the production of silica airgel to Monsanto Corp., which first introduced it to the market.

At the beginning, aerogels were sold as thickeners and used in everything, from makeup and paint to napalmThey were also used as cigarette filters and insulators for freezers.

However, Kistler's method of supercritical drying, although effective, was also dangerous, long and expensiveAll these factors meant that Monsanto ceased to produce them in the 1970s.

The real potential of airgel will not be used for several decades.

A simple recipe

Over time, scientists have created more than a dozen recipes for different types of airgel, but all have a similar process: mixing chemicals, allowing them to settle in a wet gel, and then extract the entire liquid.

The silica-based material forms a solid with a porous and fluffy structure of extremely low density, because it 99.8% volume is empty space.

It means that it is basically made of air, so it is not surprising that it is one of the lightest lumps in the world.

Surprising are the unusual properties and resistance to extreme temperatures.

But this versatility shone only then they came from the hands of NASA researchers.

Bring back memories from space

As reported by NASA, its Jet Propulsion Laboratory (JPL) in Pasadena, California has modified the original recipe for the use of airgel for space exploration, making it durable and can easily support startup and space environments.

So they could use it in rockets and other gadgets whose purpose was to travel away from Earth.

The electronic Mars Pathfinder Sojourner rover, which she explored Mars in 1997 it was isolated, for example, with an airgel.

JPL has also developed an airgel for the trap delicate interstellar particles of dust and comet They travel six times faster than a rifle bullet.

Because the airgel is so strong, you can stop it, but in order not to break up and destroy it, the density of the face they hit is smaller.

But when the particles move inside the sheet, it thickens to slow them down until they stop and are stored until they return to Earth.

Download it from the cloud

These are just some examples of miracles that NASA could do with these solid clouds.

The unique combination of physical properties – thermal, acoustic, optical and electronic – the airgel makes its potential gigantic, not only in space.

But it is still expensive and it was real obstacle.

However, efforts have been made to create cost-effective airgels, and they are already used, for example, in fire-fighting suits, in diving suits, in fireflies, in paintings and in nuclear weapons.


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