Bustling a myth: Saturn V rocket wasn’t high enough to melt concrete

Enlarge / Scientists have debunked a myth claiming that the Saturn V rocket tested on the Apollo 4 mission in 1967 was high enough to melt concrete.

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We rarely have time to write about every great science story that comes our way. So this year, we’re releasing a special Twelve Days of Christmas post series every day from December 25th to January 5th, highlighting an overlooked science story in 2022. The sound of the V launch was loud enough to melt the concrete.

The 1967 Apollo 4 mission was an uncrewed flight to test the Saturn V rocket as a viable launch vehicle for future manned missions. The test was a tremendous success and a critical step in the US space program. But the Saturn V was also incredibly loud – so loud that there was a rumor claiming that the acoustic energy was enough to melt concrete. That’s not the case, according to an August article published in a special education issue of the Journal of the Acoustical Society of America (JASA).

“Saturn V has had this kind of legendary, made-up status,” said co-author Kenneth Gee of Brigham Young University. “As part of JASA’s special issue on Education in Acoustics, we felt there was an opportunity to correct misinformation about this tool.” In addition to the author’s analysis, the paper includes several problems for students to solve about the event, including a tongue-in-cheek problem that involves using acoustic heat to make grilled cheese sandwiches.

German rocket scientist Wernher von Braun, who helped build the V-2 rocket, came to work for NASA in 1945 as part of Operation Paperclip. His mission was to share his accumulated knowledge with the Army’s rocket division. But when the Soviets launched Sputnik 1 in 1957, priorities changed and von Braun’s team was tasked with developing an equivalent US rocket. Juno 1 launched the first US satellite in January 1958 and served as a prototype of the Saturn series for deployment for Earth orbit and lunar missions.

The Apollo 4 mission launched with Saturn V at 7:00 am on November 9, 1967. When the five F-1 engines ignited eight seconds before takeoff, the sound pressure produced was so strong that the waves shook the Vehicle Assembly Building, Launch Control Center and press buildings even though the launch pad was more than three miles (five kilometers) away. far. CBS reporter Walter Cronkite and his producer had to hold on to their trailer’s viewing window as the ceiling tiles fell to the floor, fearing that the noise would shatter them. Cronkite later claimed that this was the scariest space mission he had ever undertaken. As one observer observing a Saturn V launch described:

“It’s like thunder all the time, and when you think it can’t get any higher, it gets stronger. I remember the vibration going through my bones… The bird soars, the flames gush and the thunder continues, climbing and finally a sound like a billion sheets of heavy paper tearing lengthwise for a minute. takes it out.”

One memorable thing would inspire several exaggerated claims and unsubstantiated rumors in the years that followed. my god take meat. scoured online forums and discussion boards and was appalled by the amount of disinformation proliferating there. In addition to claiming that the sound level was enough to melt concrete, there were claims that it “blazed the grass a mile away” and was powerful enough to “ignite the hairs of onlookers” and “blast rainbows from the sky”. According to the authors, “Such claims are awe-inspiring to the power of the vehicle that propels people to the Moon, but are still based on an erroneous understanding of the actual acoustic environment.”

Apollo 17 was the last moon landing for NASA’s Apollo program. The Saturn V it launched was the SA-512, the twelfth of the thirteen Saturn Vs to fly.

Their analysis of this acoustic environment includes NASA footage of the Apollo 17 launch digitized by the Discovery Channel for the 2008 documentary. Their physics-based models fixed the acoustic level at 203 decibels. Per Gee, 170 dB is equivalent to ten aircraft engines and 200 dB is equivalent to 10,000 aircraft engines.

Considering that the human threshold for pain is around 130 dB, that’s pretty high. It wasn’t high enough to melt the concrete or set the grass on fire. my god take meat. I think the myth stems from a confusion between sound power (comparable to the wattage of a light bulb) and sound pressure (similar to the brightness of a light bulb). This will lead to erroneous attempts to calculate the acoustic power of a Saturn V launch. If reports of grass burning or concrete melting turn out to be confirmed, it is most likely due to radiative heating from smoke or debris, not the sound of Saturn V.

DOI: Journal of the Acoustical Society of America, 2022. 10.1121/10.0013216 (about DOIs).

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