Sound suppression system

As engine exhaust gasses exceed the speed of sound, they collide with the ambient air and shockwaves are created, with noise levels approaching 200 db.

[2][4] The launch pad built by the Soviet Union beginning in 1978 at the Baikonur Cosmodrome for launching the Energiya rocket included an elaborate sound suppression system which delivered a peak flow of 18 cubic metres (4,800 US gal) per second fed by three ground level reservoirs totaling 18,000 cubic metres (4,800,000 US gal).

[9] The massive white clouds that billowed around the shuttle at each launch were not smoke, but wet steam generated as the rocket exhaust boiled away huge quantities of water.

[10] Launch pad 0 at the Mid-Atlantic Spaceport at NASA's Wallops Flight Facility in Virginia is equipped with a 950,000 litres (250,000 US gal) water tower 307 feet (94 m) above the ground, among the tallest in the world.

[11][12] Additional storage tanks totaling 100,000 US gallons (380,000 L; 83,000 imp gal) may be added for static fire tests.

Water is released onto an MLP at LC-39A at the start of a sound suppression system test in 2004. During launch, 300,000 US gallons (1.1 million litres) of water are poured onto the pad in only 41 seconds.