Thermal Design
Warm
Electronics Box (WEB)
Solid Silica Aerogel, sometimes called "Solid Smoke" was designed for capturing cosmic dust (on the Stardust Mission). It has excellent thermal insulation properties in the vacuum of space and the Carbon Dioxide environment of Mars.
This special aerogel is produced only at JPL and is really a lightweight form of glass. The aerogel used on the Rover has a density of approximately 20 mg/cc (or 1/50 that of water).
The aerogel is encased in a low conductivity composite box structure which supports all Rover electronics. The WEB keeps all the components within their design operating range of -40C to +40C.