QUESTION:
What is the name of the product that keeps the rover warm at night?  Is it
something like aerogly?  What company manufactures this product?

ANSWER from David Mittman on August 5, 1997:
Thanks for the question. You can find information on Sojourner's thermal
control system at several places on the Mars Pathfinder Web site. Here are
two extracts which should answer your questions:

http://mpfwww.jpl.nasa.gov/rover/descrip.html
Microrover components not designed to survive ambient Mars temperatures
(-110degC during a Martian night) are contained in the warm electronics box
(WEB). The WEB is insulated, coated with high and low emissivity paints, and
heated with a combination of 3, 1W RHUs, resistive heating under computer
control during the day and waste heat produced by the electronics. This
design allows the WEB to maintain components between -40degC and +40degC
during a Martian day.

http://mpfwww.jpl.nasa.gov/rover/thermal.html
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.

David Mittman

ANSWER from Jake Matijevic:
This fan was added to the SIM rover (the rover you see in the MarsRoom) to
enable continuous operation under room temperature and outdoors (Los
Angeles) conditions. The Warm Electronics Box (WEB) which houses the CPU and
other electronics on all versions of the rover is an excellent insulator
designed to trap heat generated by the electronics. This trapped heat soaks
out during the night on Mars so that through this passive thermal device
(insulation), the electronics are maintained within the WEB between +40degC
to -40degC while externally the rover on Mars experiences a temperature
range of 0degC to -110degC. The WEB on the SIM rover was designed just like
the Mars rover (Sojourner) WEB. Hence there is a need for support cooling
when the external temperature range in the Marsroom or outdoors is between
+40degC to +10degC.

--Jake Matijevic, Microrover Flight Experiment Manager