How high is a rocket launch?

Watch footage of Saturn V launches during NASA’s Apollo program in the 1960s and 1970s, and one thing that may strike you—even more than the polyester-heavy fashions and retro haircuts—is how far removed the spectators are from the main event.

There were several good reasons for this, and noise was one of them: loud noises can kill, and few things built by humans have been as loud as the Saturn V.

When Apollo astronauts blasted off on their missions to the Moon, they did so with more than 3 miles (5.1 km) separating them from the excited crowds of spectators. Even at such distances the noise was incredible. A common myth at the time was that the sound waves from the Saturn V’s engines were so powerful they melted concrete on the launch pad and set grass on fire a mile (1.6 km) away (both were false).

Nasa measurements at the time pegged the launch noise at 204 decibels. Compare that to the sound of a jet plane taking off, which is between 120 and 160 decibels and is considered dangerous to hear if sustained for more than 30 seconds. Even 1.5 miles away, the noise from a Saturn V launch was recorded as being 120 decibels – as loud as a rock concert or a car horn at close range.

“I’m always struck by the physicality of a launch,” says Anthony Rue, a cafe owner in Florida who has watched and photographed launches since the days of the Saturn V. “Back in the 1970s there was a sound device called Sensurround that was used in disaster films like Earthquake to create a subsonic seismic ‘experience’ in the theatre.

“Close-up launches are a bit like Sensurround,” says Rue. “You can feel a slight tremor, then a building rumble in your chest before you can hear any actual sound. The subsonic bass frequencies make your ears crackle. After a few seconds, the sound merges into a roar, like a massive welding torch.”

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Last year, a team of scientists from Brigham Young University in Utah calculated how high Saturn V was. They came up with a remarkably similar finding to Nasa’s own recordings – 203 decibels.

The difference between 160 and 200 decibels may not sound like much in the grand scheme of things, but it is.

“170 decibels would be equivalent to 10 airplane engines. Two hundred would be 10,000 engines,” said Kent Gee, lead author of the study and professor of physics at Brigham Young University at the time. “Every 10 decibels is an order of magnitude increase.”

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