Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!rpi!bu.edu!purdue!mentor.cc.purdue.edu!mace.cc.purdue.edu!dil
From: dil@mace.cc.purdue.edu (Perry G Ramsey)
Newsgroups: sci.space.shuttle
Subject: Re: The shuttle is destroying the ozone layer?
Summary: HCl is just as bad as CFC in the stratosphere
Message-ID: <5868@mace.cc.purdue.edu>
Date: 24 Oct 90 16:58:52 GMT
References: <143360@sun.Eng.Sun.COM> <10314.2711c063@pbs.org> <1990Oct23.030624.7555@cimage.com>
Organization: Department of Earth and Atmospheric Sciences
Lines: 41

In article <1990Oct23.030624.7555@cimage.com>, gregc@cimage.com (Greg Cronau) writes:
> In article <1990Oct19.022310.14985@midway.uchicago.edu> esm1@quads.uchicago.edu (Eric S. Mendelsohn) writes:
> >I heard the other day that each shuttle launch releases an enormous quantity
> >of ozone-destroying gasses into the upper atmosphere, and according to one 
> 
In article <1990Oct23.030624.7555@cimage.com>, gregc@cimage.com (Greg Cronau) writes:
> Yes, this subject was done to death awhile back.
> The facts, as I understand them, are:
> 1.) Clourine (CL) can destroy ozone by combining with it.
> 2.) CFCs (ClouroFlouroCarbons) can destroy ozone at a *MUCH* greater rate due
>     to the fact that the mechanism by which CFCs destroy ozone is catalytic.
>     That is, the CFCs are NOT consumed by the reaction, and a given CFC
>     molecule can destroy many ozone molecules before it is itself destroyed
>     by other processes. I believe that a given quantity of CFC has several
>     orders of magnitude more destructive capacity than the same quanity of CL,
>     when it comes to the break-down of ozone.
> 3.) The shuttle's SRBs produce Hydroclouric acid (HCL) *NOT* CFCs.

Definitions:  Troposphere:  The lower 10 km or so of the atmosphere.
	       There is relatively efficient mixing of the troposphere
              Stratosphere:  The region above the troposphere.  There is
	       little exchange between the stratosphere and troposphere.
	       The ozone layer is in the stratosphere.

Free chlorine in the stratosphere is the problem.  Under most circumstances,
it is difficult for chlorine to get up that high, principally because
it forms a variety of water soluble compounds and gets washed back down.
CFC's are stable and can get that high, where they are broken down by
UV and release free chlorine.  The chlorine catalyzes the destruction
of ozone in a manner similar to the that listed in point 2.  This
free chlorine is usually removed from the stratosphere when it combines
with water to make HCl.  The HCl is then scavenged by water and 
drops to the troposphere.

The shuttle, on the other hand, deposits a large quantity of stuff
directly into the stratossphere.

The SRB's don't produce CFC's, but I'm not convinced that they only
produce HCl.  

Not an expert on stratospheric chemistry: