Scientists compared NASA's SLS to a bowl of cereal — here's why

NASA's Space Launch System (SLS), the world's most powerful operational rocket, lifted the Artemis I mission toward the moon and back in November.

SLS outperformed NASA's Apollo Saturn rocket by 13 percent at liftoff, producing a loud boom as it went that could be heard from miles away.

Now, a group of scientists has reported noise measurements of the launch carried out from different locations around Kennedy Space Center. Curiously, they used a bowl of Rice Krispies cereal as a point of reference.

SLS sound study could help to combat misinformation

The new data will help scientists validate existing noise prediction models, which are required to protect expensive equipment as well as environments and communities near launch sites.

After numerous delays, SLS launched during humid nighttime conditions, allowing the researchers to view pressure waves. Take a look at the footage of the launch, shared by NASA, in the video below.

When we go, we go together.

The #Artemis team wants to thank everyone who helped us along the way toward the first launch of the @NASA_SLS rocket and @NASA_Orion. pic.twitter.com/9dBSBzQ6wI

— NASA Artemis (@NASAArtemis) November 16, 2022

The scientists, who published their findings in a paper in the journal JASA Express Letters, also claimed that their new data could help prevent disinformation spread. Last year, they disproved a widely-circulated claim that the sound emitted by Saturn V was loud enough to melt concrete.

"We hope these early results will help prevent the spread of possible misinformation, as happened with the Saturn 5," study author Kent Gee said. "Numerous websites and discussion forums suggested sound levels that were far too high, with inaccurate reports of the Saturn 5’s sound waves melting concrete and causing grass fires."

Comparing SLS to a bowl of cereal

The scientists behind the new study claimed that the SLS rocket's two solid-fuel rocket boosters (SRBs) were likely the largest sound source during liftoff, followed by the launch system's four liquid hydrogen-oxygen engines.

They investigated several sound characteristics of the launch, including a well-documented crackling sound from shock waves during rocket launches. As study author Whitney Coyle explained, "we found the Artemis I noise level at 5 km had a crackling quality about 40 million times greater than a bowl of Rice Krispies."

Overall, the researchers investigated recordings from five microphones — located between 1.5 km to 5.2 km from the launch pad — and found that they all exceeded predicted noise levels, some by as much as 20 decibels. At 1.5 km, the maximum noise level reached 136 decibels, while at 5.2 km, it reached 129 decibels.

"Although this study 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 explained. The scientific community may have a long way to go when it comes to rocket sound models, but at least we know roughly how many Rice Kripies bowls it would take to attain a similar crackling quality to the world's most powerful rocket.

Source: Press statement