posted 06-19-2001 01:54 AM            

I was lurking and noticed you had a question concerning the plumes
resulting from a shuttle launch.

While this site somewhat answers your
question and is interesting and
easy to understand, it may leave us with more questions and concerns.

I've copied a little of the web site to
give you an idea of what it's about.
Hope you'll have time to check it out.
http://paos.colorado.edu/~gatesa/aerosols/homepage.html

Aluminum Oxide Particles
in the Atmosphere

Amelia M. Gates
ATOC 5600
University of Colorado, Boulder
---------------------------------------------------------
Abstract  Welcome.  This web page was designed to provide information on aluminum oxide particles.  These particles are injected into the atmosphere by solid rocket motors (SRMs) used in many spacecraft today.  While the amount injected is relatively small compared to the background aerosol population, there is has been some speculation that these particles may contribute to local and global ozone loss, and may have some impact on the radiative properties of the atmosphere.  The injected aerosols provide a site on which chlorine activation can occur, increasing the amount of active chlorine in the rocket plume.  The active chlorine can then destroy ozone through a catalytic cycle.  Though the global impact has been shown to be small, there are indications that the local impact of rocket exhaust on ozone is significant.  The contribution to the loss from aluminum oxide aerosols has not yet been absolutely determined.  However, several studies have shown this impact to be small.  There are also indications that these particles may change the radiative properties of clouds.  This web site will hopefully serve to educate you on the importance of understanding the aluminum oxide aerosol and it's contribution to the atmosphere.

Interested in learing more?  Great!  Click on "next" to get started.  Or, follow the contents link at anytime to jump to a section of particular interest.  Arrow over a figure or word in bold to see a brief description.  Enjoy!

Section 1
Introduction

Over the last several decades, solid rocket motors (SRMs) have become a major component of most engines used in current launch vehicles.  For example, the Titan, Delta and Atlas rockets, and the space shuttle all use SRMs.  Due to the launch frequency of vehicles using SRMs, understanding the impact of their exhaust products on the atmosphere is of increasing importance.
The exhaust plume of an SRM can last from a few seconds to hours after the launch, as seen in the picture below.  Although number of aluminum oxide (Al2O3) particles emitted is relatively small, the introduction of new particles into the troposphere or stratosphere may have a significant impact on ambient atmospheric conditions.
The aluminum oxide aerosol can impact the atmosphere in several different ways.  Previous studies have shown that a significant amount of ozone loss can occur in the exhaust plume of an SRM [Ross et al, 1997a; Ross et al, 1997b; Denison et al, 1994; Jackman, 1994].  It has been determined that this loss is due to an increase in the amount of active chlorine in the plume [Brady et al, 1997; Denison et al, 1994].  While the majority of the active chlorine is a result of the afterburning of HCl in the hot plume [Denison et al, 1994], there is some speculation that heterogeneous reactions on the aluminum oxide aerosol surface may contribute to the amount of available active chlorine [Molina et al, 1997].
There are also indications that the aluminum oxide aerosol may affect the atmosphere in a more direct way through it's optical properties. The increase in ambient aerosol loading may impact cloud formation and radiative properties, as well as the radiative properties of the ambient atmosphere. This could have an impact on global warming and cooling.
The main focus of this web-site is to look at the characteristics and possible impacts of the aluminum oxide aerosols exhausted by SRMs on the stratosphere and on cloud formation in the troposphere.