What purpose would a water tank have in the proximity of a space shuttle launch?
Well, believe it or not, it is used to suppress the acoustical energy (sound and rocket exhaust reflected from the flame trench and Mobile Launcher Platform ) during launch.
NASA came up with an ingenious way to suppress the sound – bubbles!
Bubbles are excellent at absorbing the sound. They absorb the acoustic energy and as a consequence of which get heated up. NASA exploited this and sprayed water molecules in the air surrounding the Mobile Launcher Platform. This reduced the sound from the firing of the rockets by almost a half!
The Sound Suppression System
The Sound Suppression System includes an elevated water tank with a capacity of 300,000 gallons (1,135,620 liters). The tank is 290 feet (88 meters) high and is located adjacent to each pad.
The water releases just prior to the ignition of the Shuttle engines, and flows through 7-foot-diameter (2.1-meter) pipes for about 20 seconds. Water pours from 16 nozzles atop the flame deflectors and from outlets in the main engines exhaust hole in the Mobile Launcher Platform, starting at T minus 6.6 seconds.
By the time the solid rocket boosters ignite, a torrent of water will be flowing onto the Mobile Launcher Platform from six large quench nozzles, or “rainbirds,” mounted on its surface.
The peak rate of flow from all sources is 900,000 gallons (3,406,860 liters) of water per minute at 9 seconds after liftoff.
Exquisite, isn’t it?