During tests for the first shuttle missions, it was determined that the sound waves created by the massive shuttle stack at launch could possibly damage the shuttle. NASA engineers decided that the best way to "deaden" the acoustics of the noisy launch pad was to use water--and lots of it!

Both shuttle launch pads installed a Sound Suppression Water System, which is essentially a 300-foot water tank that holds 300,000 gallons of water. The water is released just before ignition of the Shuttle's engines and pours from 16 nozzles on top of the launch pad.In addition, water also is sprayed into the primary Solid Rocket Booster exhaust holes providing extra protection to the Shuttle when the SRBs ignite. The splashing water poured onto the launch pad effectively reduces the acoustical levels within the orbiter's payload bay to about 142 decibels, 3 decibels below the design requirement.

In the picture at left, the flowing water can be seen in the lower right hand side, at the very base of the launch pad.