It turns out that the launch volume of “Artemis 1” was higher than expected and it may be necessary to review the environmental assessment | sorae Portal site to space

On November 16, 2022 at 01:47 a.m. EST, NASA’s new rocket “SLS (Space Launch System) is the first mission to be used.Artemis 1Launched. The SLS was the world’s most powerful rocket ever successfully launched, with an estimated launch energy output of 39.1 million Newtons. This is 13% higher than the “Saturn V” used in the Apollo program to send humans to the Moon.

Well, the Saturn 5, which launched more than half a century ago, has been whispered about on the internet as follows.The sound of a Saturn V rocket firing was so intense that its sonic energy melted concrete and scorched grass a mile (1.6 km) away., that’s what it means. However, in a study that scientifically substantiated this urban legend,This phenomenon is impossiblewas the conclusion.

Related: Does the sound of a Saturn V launch melt concrete and burn grass? Seriously check out the urban legend! (September 3, 2022)

One of the reasons this urban legend has been sidelined for so many years is that there have been almost no major rocket launches like the Saturn V in the past half century, and the sound at launch is fresh and modern. There were no observational examples.

【▲ Figure 2: The moment the sound emitted by the SLS rocket engine occurs, you can see the appearance of a white ‘cloud’ that was not created in Figure 1. This was caused by a very loud sound[Credit: NASA]

Research team such as Kent L. Gee of Brigham Young University reported the first report of the launch sound measured at Artemis 1 launch in a paper.

Artemis 1 launched at midnight local time, and it was a wet day. Combined with the bright light on the launch pad in such an environment, the sound waves are easy to see visually. In layman’s terms, sound waves come from changes in air density, and extremely loud sounds like rocket launches create “clouds” due to changes in pressure. Indeed, the Artemis 1 launch video shows just such “clouds”.

[الشكل 3: صور خمس محطات (دبابيس حمراء في الشكل أ) وميكروفونات مثبتة في المحطات (الشكل ب والشكل ج). هذه المرة ، أصبح من الواضح أن جهارة الصوت في جميع النقاط كان أعلى من جهارة الصوت المتوقع (Credit: Gee، et.al.)]

In this study, launch sounds recorded by five microphones located 1.5 km to 5.2 km from the launch pad were analyzed. The SLS launch uses four liquid hydrogen liquid oxygen engines and two solid fuel rocket boosters, and the primary source of sound is assumed to be solid fuel rocket boosters. The loudest recorded sound was about 136 decibels at 1.5 kilometers from the launch pad, and the furthest recorded sound at 5.2 kilometers was about 129 decibels.

Interestingly, in all five recording locations, the sound was louder than previously expected. Before development of the SLS began, NASA was developing another rocket, the Ares V, which was about 40% more powerful than the SLS. An environmental assessment to predict the impact of missile launches on the environment predicted that the Ares V launch sound would be less than 110 decibels at a distance of 4.5 km from the launch site. However, the SLS’s measured firing sound this time around was about 20 decibels louder than the expected value for the Ares V, which was supposed to be a rocket with higher output than the SLS.

Sound evaluation depends on various factors such as waveform and sound frequency, as well as the weather and weather conditions of the day, so it is not easily predictable, which indicates that there is room for improvement.

The recording also revealed other interesting data. How a sound sounds to the human ear depends on its frequency characteristics. In the presence of noise such as rocket firing, it is important to determine the characteristics of the sound. For example, when analyzing with a technique called “frequency-weighted A” (*frequency-weighted characteristics within the range that human hearing can perceive), the noise level at a point 5.2 km from the launch pad is comparable to that of a nearby chain saw or lock. Indicates that a noise equivalent to that of a concert venue has been emitted.

A high-frequency sound, colloquially described as a “crackling”, was also recorded from the high-powered engine. While crackling is sometimes recorded in military jet engines, it has not been recorded in missile engines and has not been studied much. Measurements show that it recorded a crackling sound 40 million times louder than a bowl of grinding grain.

Research on extremely high sounds has not progressed due to the scarcity of their sources. This paper is an early stage analysis of missile firing sounds, and it can be said that many mysteries remain. Further analysis of the recorded sounds and additional data obtained from subsequent SLS launches may have a certain impact on future missile development.

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Text: Rare Aya