Except at the moment of liftoff, when most of the "cloud" is steam produced
when all the engines (first the SSME's, the three engines attached to the
orbiter vehicle, then also the SRB's, the large rockets on either side of
the stack) ignite. They quickly boil the deluge of water under the launch
platform (the sound suppression system, which protects the launch structure
from dangerous vibrations produced by the shuttle) and so most of what you
first see is just steam. When the solid rockets kick in, you see some
sort of beige-colored cloud, which is the solid rocket booster exhaust,
colored that way mainly by Aluminum, I think. Once away from the pad, the
main engines produce little more than a blue flame and very little visible
exhaust compared to the solids.
--
"Wer meines Speeres Spitze furchtet, durchschreite das Feuer nie!"
Roger Noe ihnp4!att-ih!uniq!rjnoe
Fox Valley Software ihnp4!nwuxf!rjnoe
Uniq Digital Technologies +1 312 510 2105
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