aerogel_factsheet.pdf

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The NASA Vision

The NASA Mission

To understand and protect our home planet,

To explore the universe and search for life,

To inspire the next generation of explorers

...as only NASA can

Aerogel

Mystifying Blue Smoke

At first sight, aerogel resembles a hologram. An

excellent insulator, aerogel has the lowest density

of any known solid — one form of this extraordi-

nary substance is actually 99.8 percent air and

0.2 percent silica dioxide (by volume). Aerogels

have open-pore structures similar to honeycomb,

but in fact they are low-density, solid materials

with extremely fine microstructures. Typically sili-

con-based like ordinary glass, or carbon-based like

common organic synthetics, aerogels possess

unique physical properties (see table). The unique

characteristics of aerogels are being applied to

meet new technological demands.

Aerogel was discovered in the late 1930s by

chemist Samuel S. Kistler. Since then, numerous

attempts have been made to further understand

and develop it. At NASA’s Jet Propulsion Labora-

tory (JPL), aerogel technology has found two pri-

mary applications. The first is the capture of dust

particles from comet Wild 2 (pronounced “Vilt 2”)

by the Stardust sample return mission. The par-

ticles gradually decelerate as they bore deeper into

the threadlike silica network of Stardust’s gradient-

density aerogel, so that the samples sustain mini-

mal damage while being collected for return to

Earth for scientific study in 2006.

To improve life here,

To extend life to there,

To find life beyond

JPL’s second application of aerogel is spacecraft in-

sulation. Because aerogel is mostly air, an effective

thermal insulator is contained within its porous

silica network. This presents an excellent thermal

barrier to protect the spacecraft against the ex-

treme cold of deep space. The Mars Pathfinder

mission used aerogel to protect the electronics

of the Sojourner rover against the frigid Martian

environment during Sojourner’s 1997 travels on

the red planet. Each of the twin Mars Exploration

Rovers, scheduled to land on Mars in early 2004,

employs aerogel for thermal insulation of the bat-

tery, electronics, and computer in the chassis, or

warm electronics box.

JPL is currently investigating a variety of future

applications for aerogel. Discussions and experi-

ments are ongoing regarding its use as a thermal

insulation material for light aircraft and spacecraft.

Aerogel’s large surface area makes it a potential

basis for chemical sensors. Aerogel may also find

a home in areas such as sporting equipment and

architectural design through corporate and aca-

demic contacts.

For more information about aerogel, visit

http://stardust.jpl.nasa.gov

Property

Density (kgm

)

Specific Surface Area

/g)

Refractive Index at

632.8 nm

Optical

Transmittance

at 632.8 nm

Coefficient of

Thermal Expansion

1/C at 20–80 deg C

Thermal

Conductivity

(W/mK) at 25 deg C

Sound Velocity (m/s)

Acoustic Impedance

(kg/m

/s)

Electric Resistivity

(ohm-cm)

Dielectric Constant

at 3–40 GHz

Silica Aerogel

5 – 200

500 – 800

Silica Glass

2300

0.1

1.002 – 1.046

1.514 – 1.644

90%

99%

~2 x 10

–6

10 x 10

–6

0.016 – 0.03

70 – 1300

1.2

5000 – 6000

1 x 10

1.008 – 2.27

1 x 10

4.0 – 6.75

Development Timeline

1930

Aerogel discovered.

1940

Aerogel first

marketed commercially.

1980

Scientific uses

of aerogel.

1997

Sojourner insulation.

1999

Stardust

launch.

2004

Mars Exploration

Rovers.

2004

Stardust encounter

with comet Wild 2.

2006

Stardust sample

returns to Earth.

2008

Future uses.

JPL 400-1119 9/03

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