Sonic boom or thunder? What you need to know as SpaceX ramps up Cape Canaveral landings

Residents and visitors will be hearing more rumbles in the coming months, and we're not referring to one of our afternoon thunderstorms.

SpaceX has announced some changes that will bring more sonic booms not only to sections of Florida's East Coast but stretching into Central Florida

For several years, Falcon 9 booster landings have taken place on drone ships in the Atlantic. Now, those boosters will be landing more frequently at Cape Canaveral Space Force Station.

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What is a sonic boom?

A sonic boom is a thunder-like noise a person on the ground hears when an aircraft or other type of vehicle flies faster than the speed of sound, according to NOAA.

Air reacts like fluid to supersonic objects. As those objects travel through the air, molecules are pushed aside with great force and this forms a shock wave, much like a boat creates a wake in water. The bigger and heavier the aircraft, the more air it displaces.

Are there single, double or triple sonic booms?

All aircraft generate two cones, at the nose and at the tail. How long they take to reach the ground primarily depends on the size of the aircraft and its altitude.

While some people on the ground may perceive the sound as a single sonic “boom,” many sonic booms produced from NASA’s research flights are easily heard as distinct “double” booms.

The Falcon 9 rocket generates a triple boom, though it sounds more like a single boom by the time it reaches spectators.

How many sonic booms are we talking about over Cape Canaveral?

Over the course of a year, there could be half dozen more booster landings at Landing Zones 1 and 2 — and just as many sonic booms when the 162-foot boosters return.

SpaceX launched 61 missions in 2022 from all three of its launch pads — two in Florida and 1 in California — averaging one launch every 6 days last year.

Elon Musk said SpaceX would shoot for 100 launches in 2023.

How far will the sonic booms be heard?

A sonic boom depends upon several factors — altitude, speed and the atmosphere.  The shape, size and weight of the aircraft or rocket also influence sonic booms, according to NASA.

The width of the boom “carpet” is about one mile for each 1,000 feet of altitude. So something flying supersonic at 50,000 feet can produce a sonic boom cone about 50 miles wide, although the sonic boom will be weaker in some areas.

The loudest sonic boom will be directly underneath the aircraft or rocket, and decreases as the distance from the flight path increases, until it ceases to exist. 

What other factors determine where sonic booms can be heard?

The direction of travel and the strength of shock waves are influenced by wind, speed, and direction, as well as by air temperature and pressure.

Why is SpaceX landing at Cape Canaveral instead of on drone ships?

"It's advantageous to get the first stage back to the landing site because then we don't have to worry about recovery weather and the drone ship," said Bill Gerstenmaier, SpaceX's vice president of build and flight reliability.

Previously, there wasn't enough fuel in the booster to make it back to the Cape. Now there's not only enough fuel to reach the Cape but enough to make it with a comfortable margin.

How many times has SpaceX landed the boosters?

Since the first touchdown at the Cape in 2015, SpaceX has successfully landed boosters 192 times.

Are sonic booms dangerous?

Though startling, sonic booms are largely harmless to humans, wildlife, and infrastructure.

However, they can be damaging if "overpressure" is high enough.

Can sonic booms damage your home or break windows?

Sonic booms are measured in pounds per square foot of overpressure, according to NASA. As overpressure increases, the likelihood of structural damage and stronger public reaction also increases. Tests, however, have shown that structures in good condition have been undamaged by overpressures of up to 11 pounds per square foot.

• 1 pound of overpressure: At one pound overpressure, no damage to structures would be expected.
• 1-2 pounds overpressure: Overpressures of 1 to 2 pounds per square foot are produced by supersonic aircraft flying at normal operating alti­tudes. Some public reaction could be expected above 1 psf.
• 2-5 pounds overpressure: Rare minor damage may occur with 2 to 5 pounds per square foot overpressure.

An FAA report on the impact of Falcon 9 launches included a section on sonic booms and concluded the highest overpressure levels, which would occur offshore, could reach 4.6 psf.

A large portion of Florida stretching from south of Orlando to south of Port St. Lucie could see overpressures of 0.1 psf. The majority of the land area within the sonic boom footprint is expected to experience overpressures of 0.25 to 0.5 psf, which is similar to distant thunder, the FAA report said.

The USAF also conducted an independent sonic boom analysis for Falcon 9 polar missions and determinedpredicted damage to public areas is very low and does not pose a safety concern

Do sonic booms register on richter scales?

While most sonic booms are not felt on land, geologists can determine whether it is an earthquake or sonic boom by looking at high-frequency signals and how wide of an area reports are received of the event, according to the U.S. Geological Survey.

Contributor: Emre Kelly, Florida Today