Ever thought that one day you will come across a heading like this one, where sound will be a threat to you. Every minute we hear different sounds, people gossiping, tick tock of a clock, symphony entering our ears and this list goes on. Before answering the question in the headline let’s first answer the following question. Can the sound of a rocket launch kill you? The simple answer to this intriguing question is a big yes. Now you must be thinking that if this is the case then how the rockets are launched. We will discuss it here but before discussing it we will have a quick review of sound.
Basically sound is the vibration that is produced by some vibrating body and these vibrations need a medium to travel. Thus we can say that sound is a longitudinal, mechanical wave. When the sound is produced then it vibrates the air molecules and a pressure wave is generated. Now this pressure wave is sensed by the sensors which are present in our inner ears. Loudness of the sound is directly proportional to the intensity of the pressure wave.
60 decibels is the normal intensity of human sound. At 90-95 decibels one will start experiencing hearing loss problem. 125 decibels and more than it causes pain in your ears and 150 decibels is enough to burst the ear drums. Now let’s talk about the sound of a rocket. A rocket launch can make a sound up to 200 decibels which is really loud and poses a threat to human life. Also the sound of a rocket launch can destroy the nearby buildings.
SOUND SUPPRESSION SYSTEM
Here we will be answering the question that is our headline too, “why doesn’t the sound of rocket launch kill you”. The answer to this question is sound suppression system. The launching sites are well equipped with sound suppression systems. Sound suppression systems either absorb or deflect the acoustic energy or high intensity sound waves that are produced during a rocket launch.
Different organizations use different methods of sound suppression systems. Some of them are:
NASA- Sound Suppression System
NASA’s earlier sound suppression system was not efficient. So it came up with a new sound suppression system that has proved to be effective. This new system of NASA makes use of water. When the engine lifts up from the launching pad then a huge amount of fire gas is exhausted in the flame trench along with a sound energy of high intensity. This sound energy is sufficient to kill a person or damage the surroundings.
Thus NASA’s launch pads consists of large water tanks. As the rocket is launched these water tanks dumps one million lbs or water onto the launch pad in just forty seconds. When the sound waves meet water, the bubbles of air absorb them. Further these bubbles contract and heat up, hence converting the sound energy into heat energy.
At the base of SRB’s large water bags are located which are made up of nylon. Water bags are one foot wide and one foot deep. Water bags are used to prevent the shock waves. Thus by using these two techniques NASA is able to reduce the intensity of sound waves from 200 decibels to 142 decibels which is equal to that of a jet taking off. This technique of NASA not only protects the surrounding from shock waves but also prevents fires that might be caused by the rockets exhaust.
SOVIET UNION / RUSSIA-Sound Suppression System
Sound suppression system used by Russia is very different from that of NASA. Russia launches its rockets from Baikanour in Kazakhstan, where temperatures are really low. During winters temperature can fall down to -40 degrees. In these conditions the water spray systems will freeze up, causing a great damage to both life and surroundings.
Thus Russia’s launch pad is made above a large flame trench. The flame trench is so large that it do not allow the shock waves to reflect back and damage the surrounding. Using this technique Russia is able to lower down the acoustic pressure that is produced by the engine.