Frozen Smoke: Scientists discuss implications of Aerogel Research
Frozen Smoke NASA Scientists Discuss Implications of Aerogel
Originally posted March 5, 1997
Updated: June 27, 1997
Your household windows may one day have a whole new look - one that saves energy and money - but you won't be able to see it. NASA scientists from the Space Sciences Laboratory at the Marshall Space Flight Center in Huntsville, Alabama, in collaboration with the Lawrence Berkeley National Laboratory in Berkeley, Calif. led by Dr. Arlon Hunt, are experimenting in space with a fascinating material called Aerogel.
Aerogel is the lightest solid material known - only three times the density of air - and has tremendous insulating capability. However, when made on the ground, it has a hazy or smoky appearance. NASA scientists are experimenting with Aerogel in space and believe that they may be able to learn how to make the foam-like material transparent. A host of new products may result for insulating windows that conserve energy and save money, by lowering heating and cooling costs.
Dr. David Noever, a member of Marshall's three-man Aerogel experiment team, believes results from recent space research indicate that they are on the right track to making the hazy material transparent enough to see through clearly. Aerogel is sometimes called "frozen smoke" because of its appearance. In its current form, Aerogel has been used in the space program as the insulating material aboard the Mars Rover launched last December.
Discovered in the 1930s by a Stanford University researcher, it's the lightest solid known. A block the size of a human weighs less than a pound, but is able to support the weight of a subcompact car or about half a ton.
"To make Aerogel clear is the challenge," said Noever. "Once you make it clear, it becomes a whole new product and it opens up a whole new world of applications. We're trying to advance technology through space research and then pass on the results to American industry for ground production."
A one-inch thick Aerogel window has the same insulation value as 15 panes of glass and trapped air - which means a conventional window would have to be ten- inches thick to equal a one-inch thick Aerogel window.
Aerogel is a good insulator because of the material's large internal
surface area. "Like the radiator in a car," said Raymond
Cronise, a member of the Marshall Aerogel research team, "it disperses
heat throughout its complex structure. It has so many sides and surfaces
that if you could unfold a sugar cube-sized portion of Aerogel, it could
cover a basketball court. This is why it disperses heat so well."
But scientists aren't exactly sure why Aerogel made on the ground is cloudy instead of clear. "We decided to take the challenge to space," said Cronise. Last April, NASA produced 16 test samples of Aerogel aboard a Starfire Rocket in a sub-orbital flight. The launch of the Starfire Rocket is shown here.
"We are very encouraged with the results from these tests," said Dr. Laurent Sibille, a staff scientist with the Universities Space Research Association and a member of the Marshall research team. "So far, the samples produced in microgravity indicate a change in the microstructure of the material compared to ground samples. These results were achieved after only seven minutes of low- gravity."
Noever said his Marshall team is preparing for the January 1998 launch of Space Shuttle Discovery, which will "fly our experiment up to where we'll be able to test Aerogel with longer exposure to low-gravity."
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Apparent density: 0.003-0.35 g/cc
Internal surface area: 600-1000m2/g
% solids 0.13-15%
Mean pore diameters ~20 nm
Primary particle diameter 2-5 nm
index of refraction 1-1.05
Thermal tolerance to 500 C
Coefficient of thermal expansion 2-4x10-6
Poisson ratio 0.2
Young's modulus 106-107 N/m2
tensile strength 16 kPa
Fracture toughness 0.8 kPa*m0.5
Dielectric constant 1.1
Sound velocity through medium 100 m/s
For more information on Aerogel research at NASA, contact
Dr. David Noever
Mail Code ES-71
NASA/Marshall Space Flight Center
Huntsville AL firstname.lastname@example.org
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