I have talked about it before, but it is so incredible that I just have to talk about it again. What is it? Why Aerogel of course, the substance that is made from 99.8% air. It is super light and it's melting point is1200 C or 2200 F. What makes this material so miraculous? It is durable and now has a new formula that makes it even lighter. It has a density of only 3 milligrams per cubic centimeter.

When a piece of foam broke off of the space shuttle it only weighed 1.67 pounds but caused great damage because of the shuttles speed. The foam used on the shuttle weighs about 2.4 pounds per cubic foot. Two different types of foam are sprayed on the fuel tanks of the shuttle. One is a closed cell type known as SLA The purpose of this foam is to keep the liquid hydrogen fuel at minus 423 F and the liquid oxygen at minus 297 F. It takes several weeks to spray on all the foam. The closed cell type foam on the fuel tanks is sprayed on in four different types. I won't go into how and where each type is sprayed because I don't want to put you to sleep but each type of closed cell type foam is sprayed in a different area of the fuel tanks. The foam must endure up to 1200 F on reentry.

Now that we know about the foam on the shuttle, lets look at aerogel again. Aerogel is made from the same material as glass but is far less dense. It is the lightest solid know to exist in the universe. This stuff is so strong that a one half pound block can support over a half ton. If you were to hold aerogel in your hand you would probably be left with dry spots on you skin because of the moisture absorbing qualities of aerogel, but the spots would disappear. Here is where aerogel shines, it prevents any type of energy transfer whether it be thermal, electrical or acoustic. So if we were to make a window that would have the same insulating properties as a one inch thick piece of aerogel, the window would have to be ten panes of glass thick with air in between each pane.

NASA has used aerogel before on some missions. It was used on the Mar's Pathfinder Rover as insulation so that the components of the Rover would be shielded from the temperature changes on the planet. It also was used on the Stardust mission which collected comet dust and material. There is only one problem with aerogel, it is very expensive. But what is expense when you are talking about a multi billion dollar space program? There doesn't seem to be a lot of the material available for use by the public either. It seems that all of the uniformed shaped pieces are reserved by NASA. So how expensive is it? A small one and one half inch tube of fragments is being sold on the internet for $25.00.

Stardust aerogel collection unit

Here we have something that is far lighter than the foam used on the shuttle and is a much better insulator. It is rated to withstand much higher temperatures than the foam that is presently used, and has been used to protect our Mar's rovers from severe temperatures. I ask you, wouldn't it make more sense to use this instead of foam on the shuttle or any space vehicle? If a piece of aerogel ever broke off, it would be far lighter thus causing less or no damage to the vehicle if it hit it. Another key factor is that since it is far lighter than the foam used now, it would take less fuel to launch the shuttle because of its overall lighter weight. Why aren't we using this stuff?

I have heard that aerogel is so good that it could replace the tiles on the shuttle that are used to shield the shuttle on re-entry. If this is true we could save a huge amount of weight and avoid the hazard of tiles coming off. One cubic inch has the theoretical ability to be flattened out so thin that it could cover a football field. As if all this wasn't enough, some scientists believe that aerogel can be made lighter in zero gravity because it is believed that the nanopores in aerogel can be made smaller.

Now with all this, you probably think that aerogel is a recent invention. As hard as it is to believe, it was invented about 75 years ago, in 1931 by two scientists working at universities in California. Aerogel remained pretty static until the 1970s when a couple of French scientists improved the way rocket fuels were stored using high quality silica aerogels. Aerogels are not all the same, there are different types, they include silica aerogels, carbon aerogels and resorcinol-formaldehyde (RF) aerogels.

There is work being carried out to make aerogels completely transparent. If it succeeds and aerogels can be produced more cheaply, then the glass windows we use today may be a thing of the past. It is said that if aerogel is used in computers as an insulator, it will enable processing speeds to double. Someday a computer cpu may be made of aerogel and it will be extremely thin and porous After all, they will be made mostly of air. Aerogel itself is only three times denser than air. Every day scientists are thinking up new uses for aerogel and it seems that it's future will be a bright one.