If you’ve ever watched STS launch (Space Transportation System launch), you would’ve noticed plenty of water flowing right under the rocket. If you have no clue what I’m talking about, watch this STS launch video:
And here’s a screenshot, just in case the video goes down –
This is a sound suppression water system and you can read more about it on NASA’s official website here.
This basically helps to protect the rocket and the platform from all the energy that’s released during the take off.
Here’s a quote from this article:
The water system is designed to protect the Shuttle and its payloads from any damage that may occur from acoustical energy reflected from the Mobile Launcher Platform (MLP) during launch. The water is released seconds before ignition of the orbiter’s three main engines and twin Solid Rocket Boosters (SRB), then flows through parallel 7-foot-diameter pipes to the Pad.
The system includes a 290-foot-high water tank filled with 300,000 gallons of water, and it empties in 41 seconds during a launch. Water pours from 16 nozzles on top of the flame deflectors and from outlets in the Shuttle main engine exhaust hole in the MLP at main engine ignition, which occurs approximately 7 seconds before liftoff.
The system was first installed at the pad when reflective energy from the top of the Mobile Launch Platform was causing minor damage to thermal curtains on the SRBs and putting stress on the wings. After adding the system, the sound pressure was reduced by half.