From: jafoust@cco.caltech.edu (Jeffrey Alan Foust)
Subject: Re: Shuttle bad for the environment?
Organization: California Institute of Technology, Pasadena
Date: Tue, 14 Apr 1992 05:44:35 GMT

	This is a frequently asked question and as such appears in the 
sci.space FAQ list, posted monthly.  It's due to be posed again in a few days,
but here's a sneak preview (well, not exactly a sneak preview: this is from
last month's FAQ list) concerning the space shuttle and its impact on the
environment:

IMPACT OF THE SPACE SHUTTLE ON THE OZONE LAYER

    From time to time, claims are made that chemicals released from
    the Space Shuttle's Solid Rocket Boosters (SRBs) are responsible
    for a significant amount of damage to the ozone layer. Studies
    indicate that they in reality have only a minute impact, both in
    absolute terms and relative to other chemical sources. The
    remainder of this item is a response from the author of the quoted
    study, Charles Jackman.

    The atmospheric modelling study of the space shuttle effects on the
    stratosphere involved three independent theoretical groups, and was
    organized by Dr. Michael Prather, NASA/Goddard Institute for Space
    Studies.  The three groups involved Michael Prather and Maria Garcia
    (NASA/GISS), Charlie Jackman and Anne Douglass (NASA/Goddard Space
    Flight Center), and Malcolm Ko and Dak Sze (Atmospheric and
    Environmental Research, Inc.).  The effort was to look at the effects
    of the space shuttle and Titan rockets on the stratosphere.

    The following are the estimated sources of stratospheric chlorine:

       Industrial sources:    300,000,000 kilograms/year
          Natural sources:     75,000,000 kilograms/year
          Shuttle sources:        725,000 kilograms/year

    The shuttle source assumes 9 space shuttles and 6 Titan rockets are
    launched yearly. Thus the launches would add less than 0.25% to the
    total stratospheric chlorine sources.

    The effect on ozone is minimal:  global yearly average total ozone would
    be decreased by 0.0065%. This is much less than total ozone variability
    associated with volcanic activity and solar flares.

    The influence of human-made chlorine products on ozone is computed
    by atmospheric model calculations to be a 1% decrease in globally
    averaged ozone between 1980 and 1990. The influence of the space shuttle and    Titan rockets on the stratosphere is negligible.  The launch
    schedule of the Space Shuttle and Titan rockets would need to be
    increased by over a factor of a hundred in order to have about
    the same effect on ozone as our increases in industrial halocarbons
    do at the present time.

    Theoretical results of this study have been published in _The Space
    Shuttle's Impact on the Stratosphere_, MJ Prather, MM Garcia, AR
    Douglass, CH Jackman, M.K.W. Ko and N.D. Sze, Journal of Geophysical
    Research, 95, 18583-18590, 1990.

    Charles Jackman, Atmospheric Chemistry and Dynamics Branch,
    Code 916, NASA/Goddard Space Flight Center,
    Greenbelt, MD  20771


Hope this helps!

-- 
Jeff Foust                        Junior, Geophysics/Planetary Science, Caltech
jafoust@cco.caltech.edu   	        	    jeff@seismo.gps.caltech.edu
"..any DEA agent or drug dealer can tell you that 1 pound equals 2.2 kilograms."
                       L.A. Times, page E1, 8 April 1992