Craig Cocca wrote:
Richard,

Do you happen to know what the thermal conductivity of BX-250/265 spray
on foam is? This is the foam that NASA uses on the ET. I'm just
curious about how it stacks up against bulk aerogel or the Pyrogel
product.

By the way, you made some really good points regarding the drawbacks of
using aerogel as an insulator on the ET. Thanks for the thoughtful
response...it's something that's often lacking around s.s.s.

Another problem.
Aerogel is generally, due to the way it's made an open-cell foam.
This is very insulating.
However, when you cool one side of it down to a few dozen K, as you would
do when it's installed, you get air condensing in the aerogel.
Aerogel filled with air is an insulator.
Aeorgel filled with liquid air isn't really so good.