Artemis I takeoff was louder than expected

14 Feb. () –

The launch last November of NASA’s Artemis I mission from Florida on the world’s most powerful rocket, the SLS, produced more noise in the environment than the models predicted.

In JASA Express Letters magazineresearchers from Brigham Young University and Rollins College in Florida report launch noise measurements at different locations around the Kennedy Space Center.

The combination of night darkness, humidity, and backlight provided a rare opportunity to see the propagation of pressure waves.

Artemis 1 was launched with four liquid hydrogen-oxygen engines and two solid-fuel rocket boosters (SRBs). According to the authors, the SRBs are likely to be the dominant noise source during takeoff.

The researchers studied the recordings from microphones located between 1.5 km and 5.2 km from the launch pad. All stations were outside the explosion hazard zone. The maximum noise levels at all five stations exceeded those expected in a preliminary assessment.

At 1.5 km from the platform, the maximum noise level reached 136 decibels. 5.2 km away, the noise was 129 decibels, nearly 20 decibels higher than predicted in a pre-launch noise model.

“This suggests the need to re-examine and possibly revise those models.said author Grant Hart.

A procedure known as A-weighting is often used to assess the impact of noise on humans. Because we don’t hear as well in some frequency ranges as in others, a filter is applied to highlight the sounds we do hear. Using this method, the researchers found that noise levels 5.2 km from the launch pad were almost as loud as a chainsaw.

The collected data can be used to validate existing noise prediction models needed to protect equipment, as well as the surrounding environment and community. This data will be useful as more powerful lift vehicles are developed, including the SLS series.

“We hope these early results help prevent the spread of potential misinformation, as happened with the Saturn 5,” said author Kent Gee. “Numerous websites and discussion forums suggested sound levels that were too high, with inaccurate reports that sound waves from the Saturn 5 melted concrete and started grass fires.”