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Foam on the Tank (Home on the Range)
Oh give me some foam, whose pieces won't roam,
from the tank, on which its attached,
with seldom the
sight, of pieces in flight,
the shuttle, it hardly gets scratched.
Foam! Foam on the tank!
Stay stuck, to
the place you're attached!
With seldom the sight, of your pieces in flight,
The shuttle, it hardly gets scratched.
Where the foam is so pure, application so free,
the makeup, so balmy and light,
That I would not so yank,
my foam from the tank,
For all the reasons so right.
Applying the foam, on that bright shining dome,
We shower
each other in streams,
where the graceful white paste, we apply with such haste,
on ourselves more than tank, so it
seems.
The old foam was best - but failed EPA's test*,
It's likely no more to return
To the tanks
of the shuttle which we might have to scuttle -
(Some lessons we just never learn.)
How often at night when the heavens are bright
With the light from the glittering stars
Have I stood there
amazed and asked as I gazed
"is the foam they have there much like ours?"
Foam! Foam on the tank!
Stay stuck,
to the place you're attached!
With seldom the sight, of your pieces in flight,
The shuttle, it hardly gets scratched.
*Environmental Protection Agency
In 1987, the United States and 45 other nations adopted the "Montreal Protocol on Substances that Deplete
the Ozone Layer."
Under the Protocol, class I ozone depleting compounds, such as Chlorofluorocarbon 11 known as CFC 11
-- the Freon-based blowing agent used in the production of the External Tank's foam -- was to be phased out of production
by the end of 1995. Production of these compounds after 1995 is allowed only by "Essential Use Exemption" and must have Montreal
Protocol approval.
After extensive testing the External Tank Project proposed hydro chlorofluorocarbon HCFC 141b as the
CFC 11 replacement. HCFC 141b is a blowing agent more environmental regulation compliant. At the same time, the Environmental
Protection Agency allowed the External Tank program to continue use of stockpiled supplies of CFC 11 until HCFC 141b was certified
for use on the Space Shuttle and phased in.
However, in 1999, the EPA proposed to expand its regulations by implementing a ban on nonessential products
that release class I ozone-depleting substances under section 610 of the Clean Air Act. Under the proposed rule, sale and
distribution of BX 250, used to insulate part of the External Tank, would have been banned because it contains CFC 11. NASA
asked the EPA to revise the proposed rule to provide an exemption for BX 250 and other foam containing CFC 11 used in applications
associated with space vehicles.
The EPA allowed the exemption but limited it to the Thermal Protection System of the Shuttle's External
Tank and only allowed the use of CFC 11 as a blowing agent when no other chlorofluorocarbons are used in the foam product.
The "new" foam containing HCFC 141b was first used on the liquid hydrogen tank aft dome of ET-82 and
flew on STS-79 in 1996. The foam was implemented on the tank's acreage, or its larger portions, beginning with ET-88, which
flew on STS- 86 in 1997. In December 2001, BX-265, which contains HCFC 141b, first flew as a replacement of BX-250. However
BX250 continued to be flown as BX-265 was implemented step wise through the manufacturing process.
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