(ORDO NEWS) — When the Artemis 1 launch vehicle was launched in November using the NASA SLS space launch system, it became the most powerful in the world, exceeding the thrust of the previous record holder, the Saturn, by 13%. At the start there was a loud roar, audible for many kilometers.
In JASA Express Letters, researchers at Brigham Young University and Rollins College in Florida reported noise measurements during the launch at various points around the Kennedy Space Center.
The data collected can be used to test existing noise prediction models that are needed to protect equipment as well as the environment and the public.
This data will be useful in the development of more powerful launch vehicles, including the SLS series.
The combination of night darkness, humidity and backlight provided a rare opportunity to see propagating pressure waves, which can be seen in the accompanying video.
Artemis-1 was launched using four liquid hydrogen-oxygen engines and two solid rocket boosters (SRBs). According to the authors, SRBs are likely to be the dominant noise source during takeoff.
The researchers studied recordings from microphones located at a distance of 1.5 km to 5.2 km from the launch pad.
All stations were outside the danger zone of the explosion. The maximum noise levels at all five stations exceeded those predicted in the preliminary assessment.
At a distance of 1.5 km from the site, the maximum noise level reached 136 decibels. At 5.2 km, the noise was 129 decibels, almost 20 decibels higher than the pre-launch noise model predicted.
“It speaks to the need to rethink these models,” said author Grant Hart.
A procedure known as A-weighting is often used to assess human exposure to noise. Because we don’t hear as well in some frequency ranges as we do in others, a filter is applied to emphasize the sounds we hear.
Using this method, the researchers found that the noise level at a distance of 5.2 km from the launch pad was about as loud as a chainsaw.
A characteristic feature of rocket launches is the crackling that occurs as a result of shock waves. These thumps are an instantaneous increase in sound pressure that is much louder than the crackling that occurs in everyday life.
Study author Whitney Coyle said: “We found that the Artemis-1 noise level at a distance of 5 km has a cod quality about 40 million times greater than that of a bowl of rice cereal.”
“While this research is an important step forward, we still have a long way to go to understand everything about the generation, propagation and perception of rocket noise,” Gee said.
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