"Craig Cocca" writes:
1) The extremely low mass of an aerogel allows for a change in
insulating material without a payload lift penalty

Probably.

2) Being a low density material, an aerogel would minimize the chance
of impact damage to the Orbiter

Probably.

3) Aerogels have extremely low thermal conductivity, even lower than
polyeurethane foam insulation

Yup.

4) Aerogels are known to be highly resilient in high-vibration
environments

They are pretty good this way, too.

However, not that aerogels are very, very, fragile, and exposure to
moisture and various other solvents does bad things to aerogel. I'm
pretty sure that addressing these issues would take enough weight and
complexity to offset the advantages.

Also if you don't want to use them in some sort of bulk fill form
(beads, powder, chunks), it's very, very, very expensive to make large
solid slabs of the stuff. Even the bulk stuff is fairly expensive. I
use a lot of aerogel 1mm beads, and they cost me around $3.5/liter,
and it's a royal pain in the ass to work with cleanly.

Like the oft-mentioned titanium, aerogel is useful stuff, but it's no
wonder-material.

There is a company called Aspen Aerogels that commercially manufactures
aerogel insulation products by the sheet. Perhaps their technology can
be be modified to suit the needs of the shuttle program.

Actually, the Aspen Aerogel product (Pyrogel[tm]) is a fine aerogel
powder embedded in a silica blanket, and it's nowhere near as
insulating as bulk aerogel (conductivity is 14.7 mW/m-K, about 5x that
of regular aerogel, which is good but not overwhelmingly impressive,
especially w.r.t. it's weight). I've got a giant roll of this stuff
in the lab that I use for projects, and I can't imagine this
particular blanket product being useful for something like the ET.

--
Richard W Kaszeta

http://www.kaszeta.org/rich