NASA’s Space Launch System rocket, scheduled for first flight early Monday, is a monster.
It’s more powerful than the rockets that have flown from Florida’s space coast for decades. An orange center stage, flanked by bright white solid rocket boosters, helps make it visually unique. And its towering height – 322 feet – makes it about 100 feet taller than other operational vehicles launched from the Eastern Range.
On liftoff, scheduled for 8:33 a.m. EDT Monday, all of these factors and more will combine to make this one of Florida’s strongest and loudest launches to date. At least 100,000 visitors are expected in areas around the Kennedy Space Center for the mission known as the Artemis I, which will take an uncrewed Orion capsule on a 42-day flight to the moon and back. Pad 39B will be the host.
In the event of a delay, two backup opportunities — September 2 at 12:48 p.m. and September 5 at 5:12 p.m. EDT — are available for SLS.
What will Artemis I look like?
A look on social media indicates that some viewers expect SLS to be significantly louder than Saturn V, the Apollo-era rocket that took astronauts to the moon.
But in reality, hearing and feeling the power of SLS – or any rocket for that matter – will depend on a host of factors surrounding viewing sites. Everything from winds to humidity to trees can change what you hear and feel.
“Put That First: It’s Gonna Be Loud” John Blevins, NASA’s chief SLS engineer, told FLORIDA TODAY. “Nobody will be in danger, but it will be as loud as a Saturn V rocket.”
But there will be variations, many of which will depend on location and local weather.
“If you have the same environmental conditions — the same location, humidity, and wind — SLS will be stronger than Saturn V and the Space Shuttle,” Blevins said. “But decibel level is an extremely loud function of where you are.”
The difference in the amount of sound, at least in part, comes down to how powerful SLS is: 8.8 million pounds of thrust is more than Saturn V and the Space Shuttle. Besides the solid rocket boosters, SLS actually uses four old RS-25 Shuttle Motorstherefore some similarities are expected.
On the weather side, almost all factors play a role: humidity, cloud cover, wind direction. More humidity, for example, makes sounds louder. SLS would be about 20% stronger on a day at 90% humidity compared to a day with 10% humidity, Blevins said.
“Sound travels faster in moist air than in drier air. It will be louder on a very humid day than it will be on a drier day from the viewer’s perspective,” Blevins said.
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Wind direction, on the other hand, plays a role in the direction sound travels, while clouds can actually help sound travel long distances. SLS will produce a fair amount of low-frequency rumble from its massive side-mounted solid rocket boosters.
“Let’s just say we had a cloud shelf at 1,000 feet stretching from here to Tampa,” he said. “They would have a huge rumble in Tampa. The sounds would bounce off that cloudy bridge. The noise would just bounce back and forth and continue to travel with the wind.”
But one of the lesser-known impacts, at least from a public perspective, is vegetation.
“After I finished my PhD, I did a lot of aerodynamics and acoustics consulting. We were testing the (Air Force’s) F-22 jet engine in the 1990s and neighbors complained because it was long hours of testing,” Blevins said. “So we literally planted 1,000 acres of 6-foot-tall pines and that drowned out all the noise. Vegetation is a huge brake.”
While these factors impact the experience, there’s no other way to explain it to locals: SLS won’t be shy. Its strongest point, at least when measured by pad instruments, will occur just after liftoff from Pad 39B when rocket thrust interacts with the pad’s infrastructure.
Due to the variety of factors involved, it is difficult to say what level of decibels viewers can expect. But those watching from popular sites at or near KSC will likely experience sounds north of 100 decibels, equivalent to a jackhammer.
Blevins knows the rumble will get him and his team to KSC Launch Control Center proud of their work. But he hopes it will inspire others too.
“It helps all of our industries. It helps our industrial base. People will see these launches and maybe end up designing planes and cars, which is what I was doing coincidentally a few decades ago. It will inspire them to launch in engineering and doing great things with their hands, science and technology,” he said.
What will the Artemis I launch look like?
Florida can often be the butt of jokes for its lack of hills, but that can be an advantage for spectators. Once SLS clears trees and buildings, most townspeople attending the launch should have spectacular views.
That’s not to say outsiders won’t be able to see it as some daytime launches are seen up to a 150-mile radius around KSC, including areas like Tampa, Orlando and Jacksonville. Because Monday’s trajectory takes SLS to the northeast, people in areas like Miami hoping to see it might at best make out a bright spot.
The size of SLS compared to other operational rockets will help make it more visible once in the air:
- SLS: 322 feet, 8.8 million pounds thrust
- SpaceX Falcon 9 and Falcon Heavy: 230 feet, 1.7 million pounds and 5.1 million pounds of thrust, respectively
- United Launch Alliance Atlas V: depending on configuration, 188 to 215 feet and 860,000 pounds to 2.7 million pounds of thrust
But seeing the rocket after liftoff and separation from the massive solid rocket boosters – scheduled for T-plus 2 minutes and 12 seconds as the rocket travels 3,170 mph – will likely come down to local cloud cover. If cloudy conditions are expected near the observation sites, this could easily obscure most of the launch process, although it will still be audible.
Marc Archambault, a Associate Professor from aerospace, physics and space science at Florida Tech, agrees with Blevins: it will all depend on location and local conditions. He expects to see SLS from the university’s main campus in Melbourne, which is about 38 miles from the pad in a straight line.
“Winds for some, atmospheric conditions in general, cloud cover and humidity, and what’s between you and the rocket” will all make a difference, Archambault said. “It’s a very big deal. Those of us in the industry are particularly concerned, but for those who also live here and casually follow this stuff, it’s still a big deal.
Contact Emre Kelly at aekelly@floridatoday.com or 321-242-3715. Follow him on Twitter, Facebook and instagram to @EmreKelly.
Launching Monday, August 29
- Rocket: NASA’s space launch system
- Mission: Artemis I
- Launch time: 8:33 a.m. EDT
- Launch window: two hours
- Launch Pad: 39B at Kennedy Space Center
- Trajectory: North-East
- Duration: 42 days
- Backup Launch Windows: September 2 at 12:48 p.m. and September 5 at 5:12 p.m. EDT
Visit floridatoday.com/space at 5 a.m. on Monday, August 29 for real-time updates and live video.