Do NASA's engines destroy the Ozone Layer

Just to comment, freon is not used to cool rocket engines. Don't know where
the original poster got that idea.

Rocket engines are typically cooled by the fuel or oxidizer brought used to
propel the craft. There's little enough mass margin as is, they can't waste
any on what would be an ineffective coolant.



Freon is used to cool the shuttle itself:

http://www.cnn.com/2002/TECH/space/0...oblem/?related

It is not true that ground relesed freon is "too heavy" to reach the ozone
layer:

http://rpuchalsky.home.att.net/sci_env/dixy_1.txt

1.: Vertical distribution of atmospheric gases

p. 35: "How does CFC rise when its molecules are four to eight times
heavier than air? All experience with freon and related CFCs shows
that they are non-volatile and so heavy that you can pour CFCs from
a container and if some of them spill, they will collect at the lowest
point on the ground where soil bacteria will decompose them. Of
course, some molecules will be caught in upward air eddies or
otherwise carried upwards, but this is a very small fraction of the
total."

This seemingly plausible objection merely demonstrates that the authors [Dixy
Lee Ray and Lou Guzzo]
do not understand the mechanisms of vertical transport in the
atmosphere. It has long been known [Wallace and Hobbs] that gases do
not segregate by weight in the first 80 km of the atmosphere, an
altitude range that extends well above the ozone layer. Molecular
weight is entirely irrelevant for determining the chemical composition
in the troposphere and stratosphere. The mixing of atmospheric gases
takes place by turbulent processes that do not distinguish molecular
masses - the rare heavy particles are carried along by the much more
numerous light ones. Thus, for example, the ratio of oxygen to nitrogen
is constant up to ~100 km (the ozone layer lies between 15 and 50
km.)

Now one might argue that CFC's are quite a bit heavier than most
molecules in the atmosphere; perhaps the mixing mechanisms are strong
enough to keep the O2/N2 ratio constant, but not to sustain the heavier
CFC molecules. Rowland and Molina considered this point carefully in
their 1975 review [Rowland and Molina]. At that time CFC's had not
yet been measured in the stratosphere, so they examined data on
atmospheric concentrations of heavy inert gases. These data showed
that the relative proportions of Krypton (mass 84), Argon (mass 40)
and Neon (mass 20) between 40 and 60 km were within 0.5% of those
measured at ground level. Shortly thereafter, direct measurements of
CFC's themselves as a function of altitude began; the very first such
measurements showed that the CFC mole fraction is virtually
independent of altitude up through the troposphere and lower
stratosphere, then drops off suddenly at altitudes in which the
molecules are exposed to UV radiation. It is a molecule's UV absorption
spectrum, not its weight, that determines its distribution in the
atmosphere. Even more revealing are measurements of the fluorocarbon
CF4. This extraordinarily persistent molecule is not dissociated by the
UV wavelengths that are abundant in the stratosphere, and thus serves
as a tracer for vertical motion. The mole fraction of CF4 has been
measured and found to be essentially independent of altitude all the
way up to the top of the stratosphere at 55 km. [Fabian et al.]
[Zander et al. 1992]


===========================


Anti-environmental myths
http://info-pollution.com/myths.htm
Practical skepticism
http://info-pollution.com/skeptic.htm

On 26 Sep 2003 13:26:09 GMT, (Jim Norton) wrote:

Just to comment, freon is not used to cool rocket engines. Don't know where
the original poster got that idea.

Probably from Nexus Magazine. He's a credophile


thanks to all for the explanations.



Rocket engines are typically cooled by the fuel or oxidizer brought used to
propel the craft. There's little enough mass margin as is, they can't waste
any on what would be an ineffective coolant.



Freon is used to cool the shuttle itself:

http://www.cnn.com/2002/TECH/space/0...oblem/?related

It is not true that ground relesed freon is "too heavy" to reach the ozone
layer:

http://rpuchalsky.home.att.net/sci_env/dixy_1.txt

1.: Vertical distribution of atmospheric gases

p. 35: "How does CFC rise when its molecules are four to eight times
heavier than air? All experience with freon and related CFCs shows
that they are non-volatile and so heavy that you can pour CFCs from
a container and if some of them spill, they will collect at the lowest
point on the ground where soil bacteria will decompose them. Of
course, some molecules will be caught in upward air eddies or
otherwise carried upwards, but this is a very small fraction of the
total."

This seemingly plausible objection merely demonstrates that the authors [Dixy
Lee Ray and Lou Guzzo]
do not understand the mechanisms of vertical transport in the
atmosphere. It has long been known [Wallace and Hobbs] that gases do
not segregate by weight in the first 80 km of the atmosphere, an
altitude range that extends well above the ozone layer. Molecular
weight is entirely irrelevant for determining the chemical composition
in the troposphere and stratosphere. The mixing of atmospheric gases
takes place by turbulent processes that do not distinguish molecular
masses - the rare heavy particles are carried along by the much more
numerous light ones. Thus, for example, the ratio of oxygen to nitrogen
is constant up to ~100 km (the ozone layer lies between 15 and 50
km.)

Now one might argue that CFC's are quite a bit heavier than most
molecules in the atmosphere; perhaps the mixing mechanisms are strong
enough to keep the O2/N2 ratio constant, but not to sustain the heavier
CFC molecules. Rowland and Molina considered this point carefully in
their 1975 review [Rowland and Molina]. At that time CFC's had not
yet been measured in the stratosphere, so they examined data on
atmospheric concentrations of heavy inert gases. These data showed
that the relative proportions of Krypton (mass 84), Argon (mass 40)
and Neon (mass 20) between 40 and 60 km were within 0.5% of those
measured at ground level. Shortly thereafter, direct measurements of
CFC's themselves as a function of altitude began; the very first such
measurements showed that the CFC mole fraction is virtually
independent of altitude up through the troposphere and lower
stratosphere, then drops off suddenly at altitudes in which the
molecules are exposed to UV radiation. It is a molecule's UV absorption
spectrum, not its weight, that determines its distribution in the
atmosphere. Even more revealing are measurements of the fluorocarbon
CF4. This extraordinarily persistent molecule is not dissociated by the
UV wavelengths that are abundant in the stratosphere, and thus serves
as a tracer for vertical motion. The mole fraction of CF4 has been
measured and found to be essentially independent of altitude all the
way up to the top of the stratosphere at 55 km. [Fabian et al.]
[Zander et al. 1992]


===========================


Anti-environmental myths
http://info-pollution.com/myths.htm
Practical skepticism
http://info-pollution.com/skeptic.htm

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