What They Learn In Texas Will Inform Starship Sound Modeling For the Space Coast

As SpaceX’s Starship prepares for an ambitious launch schedule here at on the Space Coast at Kennedy Space Center, residents’ concerns about its acoustic impact on surrounding communities and environments have come to the forefront.

Dr. Kent Gee, a physics professor and Department Chair of the Physics and Astronomy department at Brigham Young University (BYU) leads a team dedicated to understanding the noise generated by this powerful rocket. He and his team of researchers have conducted sound studies for Starship in Texas and the SLS at Kennedy Space Center, yielding some interesting results.

SpaceX has stated that they plan to launch Starship from KSC this year, and indeed, construction of the launch mount for the world’s most powerful rocket continues apace at LC-39A. While a Starship launch from the Space Coast in 2025 may be an ambitious plan, it is safe to say that within the next year the area will see, hear and feel this rocket as it climbs off the launch pad and makes its way to orbit from Florida.

Artemis Testing

“I took the students to church and we were talking to people at Merritt Island,” Dr. Gee related to Talk of Titusville. “They said, oh, you’re from BYU, what are you doing here?”

“Everyone, every single person we talked to said they wanted to tell us that some Falcon 9 launches like rattled their windows and other ones you didn’t hear at all.”

Such stories are common on the Space Coast. Some days, one may barely hear a Falcon 9 in some areas of the region, while others in other places watching the same launch from a different place might report their windows rattling or their dog barking because of the thunder-like sound of the ascending rocket.

Measuring the acoustic impact of rockets like Starship is complex due to factors like atmospheric conditions and the rocket’s trajectory. Dr. Gee’s team utilizes various sound metrics, including A-weighted and Z-weighted Decibels, to capture a comprehensive picture of the noise levels. Their findings suggest that current environmental assessments may underestimate the true acoustic impact of such launches.

Dr. Gee told us “there’s a paper that we published on the Artemis I launch. We went due west [from the launch site.] I had people sitting there [about 30 km] due west.”

“I was on the other side of the Indian River south of Titusville, about 30 kilometers, basically southwest of [the launch pad.] We were about the same distance [as the team that was due west.] I got about 100 decibels where I was.”

The team located due west? Dr. Gee explained, “They didn’t even hear the noise at 30 kilometers.”

That may seem odd, but again, sound propagation is affected by a number of factors: local weather, winds, ambient humidity and of course the direction the rocket is flying.

Dr. Gee explained that the sound he experienced from Artemis was like many other launches with “Low frequencies. It was not quiet, but because it was such low frequencies, it wasn’t like overwhelmingly loud, but it was it was about what I expected, having been to prior launches and guessing.”

Dr. Gee added that “At [some places] 50 km [from the launch site,] it was like 80 Decibels and so it was like it hit like right across the Indian River. Maybe because the land mass was warmer and so you got upward refraction [of the noise] and then it bent back down.

“There’s some complicated stuff going on,” he added.

That would explain the wildly varying accounts of how loud Artemis I was in different parts of the Space Coast region. Some said it was almost quiet, others reported a teeth-chattering experience. It all depended on where the observer was located and whether the local conditions were favorable to sound traveling from the ascending SLS rocket to where they were.

How Loud Will Starship Seem?

Dr. Gee’s research in Texas reveals that a single Starship launch produces noise levels equivalent to 4–6 Space Launch System (SLS) launches or at least 10 Falcon 9 launches. Measurements taken during Starship’s fifth and sixth test flights indicated that even at distances of 10 kilometers, the sound was as loud as a rock concert. At 20 kilometers, it matched the noise level of a table saw or snow blower, and at 30–35 kilometers, it was comparable to a vacuum cleaner or hair dryer. That’s pretty loud.

“It’s got this low-frequency rumble that’s just overwhelming,” Dr. Gee explained. “And then on top of it, you have this kind of high-frequency popping. I call it crackle. It’s a very unique sound experience.”

In their paper, “Starship super heavy acoustics: Far-field noise measurements during launch and the first-ever booster catch“, Dr. Gee and his team notes that the booster return resulted in a louder sound from the sonic boom that heralds the return of the booster.

The highest-amplitude event at all eight stations is the flyback sonic boom which set off car alarms at Stations 2 (10.1 km) and 4 (16.6 km). A prior Falcon 9 study (Anderson , 2024) shows near the landing pad, maximum launch noise exceeds the flyback boom, but that there is a range (∼2 km for the Falcon 9) beyond which the cylindrically spreading boom’s overpressure becomes larger in amplitude than the spherically spreading launch noise. The booster’s flyback boom’s overpressure of 7.1 psf (0.34 kPa) is part of a clean triple-shock waveform that is similar to Falcon 9’s signature (Anderson , 2024), despite the fact that Falcon 9 has a different geometry. An ongoing investigation into the aeroacoustic origins of Falcon 9’s triple boom, when complete, should also provide insights into the Super Heavy flyback boom.

Starship super heavy acoustics: Far-field noise measurements during launch and the first-ever booster catch, Dr. Kent Gee, et. al, JASA Express Lett. 4, 113601 (2024)

Sounds Like Apollo

If that’s reminiscent to old-timers in the area of the venerable Saturn V from the Apollo program, they aren’t far off. Saturn V launches were well known for their low-frequency rumbles, which gave launch spectators the feeling of the Earth shaking below their feet.

The sound power produced by SLS (202.4 dB) is still extremely loud. We compared the launch noise levels recorded at 5 km away from the rocket to the sound levels of a fresh bowl of crackling Rice Krispies® and found that SLS’s noise intensity at this distance from the rocket was approximately 40 million times greater than the crackling of cereal. If this comparison only leaves you more confused, you can think of it being about as loud as operating a chainsaw (but with the rocket over 5 km away).

Taggart Durant, “SLS vs. Saturn V: Which Was Louder?”

Effects On Wildlife?

The intense noise levels in Texas have raised concerns about potential impacts on nearby communities and wildlife there in the lower Rio Grande area and for people here on the Space Coast. Residents have reported instances of car alarms being triggered and windows rattling due to the sonic booms. Dr. Gee emphasizes the need for further studies to understand the long-term effects of repeated exposure to such noise, especially with plans for frequent launches.

Starship Will Be Louder Than Falcon 9

“Titusville, Merritt Island, Cape Canaveral, those, those towns are, are gonna see greater sound levels than what you get with the Falcon 9,” Dr. Gee said.

As for the Starship Heavy noise experienced in Texas, “people are in Port Isabel — about 10 km away in Texas — they’re not reporting broken windows [after a Starship launch,]” he added. 10 km, or about 6.2 miles, is closer than any private property near LC-39A.

“I even suggested that resident surveys in the Boca Chica region would be helpful in assessing long range impacts.” Then Dr. Gee added, “I have to be careful because I don’t want to make people think that I’m calling out SpaceX saying you should XYZ. To me that’s the FAA or whoever’s job to say you ought to be looking at this because you could be gaining additional data that would be helpful in Florida.”

Those sound studies are underway, as part of the Environmental Assessment being completed by the FAA and NASA for the venerable launch complex.

Dr. Gee added, “We’re trying to put out information that we feel, feel like is helpful to provide a, to paint a realistic picture of where this rocket fits in with other rockets and what sound levels might be expected according to at least the propagation over two flights of what we measured in the field.”

The town of Cape Canaveral is embarking on sound studies, according to a recent report in Florida Today. Rick Neale reported in an article “Ahead of Starship’s arrival, Cape Canaveral to study rocket launch noise, vibrations” that:

“In a proactive move, the Cape Canaveral City Council unanimously approved an upcoming $10,019 rocket launch impact study with the Florida Institute of Technology. Researchers will install sensor suites this summer at a handful of municipal and privately owned buildings across the 1.9-square-mile city, collecting data on decibel levels, vibrations and air quality before, during and after every launch through at least May 2026.”

Dr. Gee concluded that more data is needed to fully understand the noise effects of rocket launches, “There’s longer term impacts that we just don’t quite understand yet. And I think that’s, there’s opportunities for the science to catch up.” With the City of Cape Canaveral monitoring every launch from preset locations, models that Dr. Gee and the BYU team create will only be more informative.

One thing is certain: the Eastern Range is only going to get busier as more companies conduct more launches with more powerful rockets. While Starship, SLS, and Falcon 9 get all of the attention, New Glenn and Vulcan are also in the mix, and that’s before Relativity, Vaya Space, and others join the fray.

The LC-39A EIS

The ongoing environmental assessment for Launch Complex 39A (LC-39A) at Kennedy Space Center involves SpaceX’s Starship-Super Heavy launch and landings, with an expected high level of activity at the site.

The Federal Aviation Administration (FAA) is preparing an Environmental Impact Statement (EIS), not an Environmental Assessment (EA), due to changes in the vehicle’s design and operations since the 2019 EA, which found no significant impact.

The EIS process was initiated with a Notice of Intent published on May 10, 2024, and scoping meetings were held in June 2024 to gather public input. A release date for the Draft EA has not yet been announced.

In the document above, the FAA lays out its noise metrics that will be considered for the ongoing EIS.