Aerogel as ET Insulator

Has it ever been suggested to replace to the foam on the ET with an
aerogel insulator? Material science is far from being one of my areas
of expertise, but it would seem that an aerogel insulator would be a
win-win proposition:

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

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

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

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


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.

Any takers?

-Craig

"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

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.

Craig

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.

"Craig Cocca" writes:
Do you happen to know what the thermal conductivity of BX-250/265 spray
on foam is?

Nope. I don't think anyone uses either of those except NASA. (And my
last efforts at getting info on ET foam around the time of the
Columbia incident with my NASA contacts got me nowhe I got
incorrect info).

However, I do know that it's a polyurethane foam, and a good
high-performance polyurethane films can be as good as 0.03 W/m-k,
which is on the same order as aerogel.

--
Richard W Kaszeta

http://www.kaszeta.org/rich

Richard,

On Aspen's web site, they have the thermal conductivity of their
aerogel silica blankets pegged at 0.014 W/m-k. Is this a somewhat
reasonable number, or is that just marketing?

Also, are you familiar with a product called CryoCoat? I found a study
online that suggests that it is usable as a foam replacement for the
ET. Do you know what the pros and cons of using it would be?

Craig

"Craig Cocca" writes:
On Aspen's web site, they have the thermal conductivity of their
aerogel silica blankets pegged at 0.014 W/m-k. Is this a somewhat
reasonable number, or is that just marketing?

That's a fairly reasonable number. (In fact, I may have erred in my earlier
post, it appears that some of the Aspen blankets are much closed to
bulk aerogel than I may have stated).

Also, are you familiar with a product called CryoCoat? I found a study
online that suggests that it is usable as a foam replacement for the
ET. Do you know what the pros and cons of using it would be?

Cryocoat is a much more appropriate product (and, IIRC, it has been
used for cryogenic tank insulation on various launch systems).

--
Richard W Kaszeta

http://www.kaszeta.org/rich

How about something that is really light and just keeps peeling off? On
the pad it might be very thick (2-3 inches) and then during ascent it is
intentionally made to shed in little ash-like deteriorations over the
varying pressures it encounters into orbit?

If its light enough stuff it might even make the ET recoverable. Or
held in a spray tank and applied in space later to make de-orbits
possible for a lot of things..

How about gorilla glue and feathers?


Thanks,

Rick



Richard Kaszeta wrote:
"Craig Cocca" writes:

Do you happen to know what the thermal conductivity of BX-250/265 spray
on foam is?


Nope. I don't think anyone uses either of those except NASA. (And my
last efforts at getting info on ET foam around the time of the
Columbia incident with my NASA contacts got me nowhe I got
incorrect info).

However, I do know that it's a polyurethane foam, and a good
high-performance polyurethane films can be as good as 0.03 W/m-k,
which is on the same order as aerogel.

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

To take this completely off-topic - where from?

Ian Stirling writes:
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.

To take this completely off-topic - where from?

www.cabot-corp.com/nanogel, although you can't buy it in any quantity
less than 200 liter barrels (although if you think you have a real use
for it, they've send me lots of small ~2 liter samples for testing).

--
Richard W Kaszeta

http://www.kaszeta.org/rich