23 Do Space Shuttle launches damage the ozone layer?
Description
This article is from the Ozone Depletion FAQ, by Robert Parson rparson@spot.colorado.edu with numerous contributions by others.
23 Do Space Shuttle launches damage the ozone layer?
Very little. In the early 1970's, when little was known about
the role of chlorine radicals in ozone depletion, it was suggested
that HCl from solid rocket motors might have a significant effect
upon the ozone layer - if not globally, perhaps in the immediate
vicinity of the launch. It was immediately shown that the effect
was negligible, and this has been repeatedly demonstrated since.
Each shuttle launch produces about 200 metric tons of chlorine as
HCl, of which about one-third, or 68 tons, is injected into the
stratosphere. Its residence time there is about three years. A
full year's schedule of shuttle and solid rocket launches injects
725 tons of chlorine into the stratosphere. This is negligible compared
to chlorine emissions in the form of CFC's and related compounds
(~1 million tons/yr in the 1980's, of which ~0.3 Mt reach the
stratosphere each year). It is also small in comparison to natural
sources of stratospheric chlorine, which amount to about 75,000 tons
per year. [Prather et al. 1990] [WMO 1991] [Ko et al.]
See also the sci.space FAQ, Part 10, "Controversial Questions",
available by anonymous ftp from rtfm.mit.edu in the directory
pub/usenet/news.answers/space/controversy, and on the world-wide web at:
http://www.cis.ohio-state.edu/hypertext/faq/usenet/space/controversy/faq.html
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