A groundbreaking study on rocket-related noise linked to Vandenberg Space Force Base launches has confirmed wind pattern, seasons, trajectory and other factors contribute to the level of sounds heard around the Central Coast.

“We’re literally writing the physics behind this phenomenon,” Col. James “Jim” Horne, Space Launch Delta 30 commander said during the inaugural Mission Update speakers series in Lompoc Feb. 20.

Horne will hold another Mission Update from 3:30 to 5:30 p.m. Tuesday at the County Planning Commission Hearing Room, 123 E. Anapamu St. in Santa Barbara. Additional Mission Updates are planned in Carpinteria and Ojai in the coming months. 

The noise study involves a partnership between Vandenberg along with Brigham Young University and California State University, Bakersfield. 

The proximity of a rocket’s trajectory or flight path along with when the liftoff occurs can contribute to what people hear.

“So we can launch the same trajectory in the summer and you won’t even hear it,” Horne sad. “But if we launch it in the winter or the spring, you might. You might, not necessarily will, but you might.. You’re more likely to hear it during those times and that’s because of the seasonal wind patterns pushing onshore versus offshore during the summer.”

With sensors dotting areas located between northern Santa Barbara County and Oxnard, some 477 recordings have been collected as of February. 

“We’re learning a lot. We’re learning that our tools are not equipped very well for this phenomenon and now they are,” Horne said. “That’s giving us the opportunity and the information to design policy constraints  and other operational constraints to minimize the noise impacts. 

Kent Gee, from the BYU Physics Department and lead researcher for the study, said they want to place more sensors to collect even more information as they learn about the four phases of launch noise.

He has been surprised to see how variable the sonic booms are as they’re heard and felt over a wide swath spanning from Santa Barbara to Oxnard.

“When we started I didn’t understand exactly what they were experiencing. Now because of the modeling and the measurements we made we actually do understand what that is,” he said. 

The area where the sound waves hit the ground is known as the focus, Gee said.

For one launch studies showed the  most intense sonic booms occurred between Santa Barbara and Carpinteria, Gee said. 

“A lot of people will see a sonic boom, but it’s less intense for them,” Gee said. “So understanding where that focus occurs is one of our key challenges because that’s the people who are most impacted for anything we launch.”

He has placed equipment including a black dome container affectionally known as COUGAR (BYU’s mascot). COUGAR stands for Compact Outdoor Unit for Ground-based Acoustical Recordings that is a weather-proof container for collecting the data.

“Dr. Gee is anxious for data as any scientist is so if you have folks that you know, or if you are interested, in being part of that  study he will gladly put sound equipment in your backyard and add it to his modeling,” Horne said during a recent State of Vandenberg event at the base last week.

Anyone willing to have one of the sensors place on their property can contact Gee by sending an email to kentgee@byu.edu.

Science of Sonic Booms 

Gee has logged some 25 years studying military noise including aircraft, explosives and  rockets, landing him in Lompoc frequently in recent years.

“This is our most extensive work so far,” Gee said of the Central Coast project. “I would say Vandenberg has led the charge.”

Rocket launch noise has various phases with liftoff creating rumbles and crackles. 

“As it accelerates and pitches over and goes downrange you will generate an ascent sonic boom,” Gee said. “That’s one type of sonic boom that’s generated.”

The booster’s flyback to Vandenberg for landing creates what can be clapping sonic booms heard in Lompoc.

Sonic booms are generated by super sonic vehicles traveling faster than the speed of sound. 

“A sonic boom is basically a wave,” Gee said.

So what is noise? 

“Noise is a sound that is unpleasant, disturbing, annoying, unwanted and it has different effects,” he said, adding, “noise is a concern as a possible impact of any military related activity.”

All communities wrestle with determining an acceptable threshold for noise which can lead to a differences of opinion.

“Physics is easy. Psychology is hard,” Gee said.

In addition to analyzing noise impacts on its human neighbors, another study is assessing how noise affects the various endangered species living at Vandenberg.

Rockets launching from Vandenberg generate a significant amount of power at liftoff, Gee said. The energy generated by one liftoff amounts to the equivalent of hundreds of military aircraft,  Gee said.  

One goal of efforts to learn about launch noise is to create tools possible leading to faster, better, more reliable environmental assessments to identify real impacts.

As United Launch Alliance prepares to debut its Vulcan vehicle with a launch later this year on the former Atlas 5 facility, Gee said measurements show the new rocket produces the similar noise as its predecessor. That’s despite the fact Vulcan boasts substantially greater thrust at liftoff. 

“Why? We don’t know yet. But it does suggest that there may be in the future  the possibility of influencing launch vehicle design for the purpose of noise reduction,” Gee said.

Following Tuesday’s Mission Update presentation in Santa Barbara, others are planned from 4-6 p.m. April 22 at the Veterans Memorial Building, 941 Walnut Ave. in Carpinteria and 4-6 p.m. May 6 at the Kent Hall Council Chambers on the Ojai City Hall campus, 111 W. Santa Ana St. in Ojai.