SpaceX has provided a rare update regarding sonic booms in anticipation of the upcoming fifth Starship orbital flight test. This update, shared on July 29, is quite unusual as the company typically reserves such communications for significant events, such as the recent Falcon 9 failure investigation or the results of a Starship test flight.
The update, shared on the company’s website, hints at a notable milestone for SpaceX: a Return to Launch Site (RTLS) Booster landing attempt for the Super Heavy Booster.
This maneuver involves the booster returning to the launch site and being caught mid-air by the “chopsticks”, two arms designed to catch the booster and place it back on the launch mount.
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An expected move
SpaceX’s CEO Elon Musk alluded to this ambitious plan following the latest Starship launch in June 2024.
During that flight, after the successful ascent phase of the launch, Starship successfully executed the “hot-stage” separation, and all the 13 central engines on the Super Heavy booster re-ignited, completing the boostback burn and directing the booster toward the planned landing zone.
The hot staging ring separated from the first stage to reduce weight, and the booster continued its descent without issues until 1 km altitude, where 12 Raptors successfully ignited, simulating a nominal landing burn. Super Heavy then settled on the sea’s surface, splashing down softly in the Gulf of Mexico.
Aiming to try this in late July!
— Elon Musk (@elonmusk) June 15, 2024
Musk’s remarks set the stage for the upcoming RTLS and catch attempt, a critical step toward SpaceX’s goal of full and rapid reusability of the Starship system.
The next Starship flight could potentially take place in late August or early September, according to Musk. This is pending regulatory approval, since the FAA must grant SpaceX a launch license modification which includes the new flight plan and objectives.
The company is also seeking approval for increased Starship launches and landings at its Starbase facility in Boca Chica, TX, as detailed in the FAA’s Draft Tiered Environmental Assessment released on Monday, July 29.
If approved, SpaceX plans to increase the number of Starship launches from five to as many as 25 annually. Additionally, the number of landings would rise from 15 to 50 per year, with 25 each for Starship and Super Heavy.
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So… Why sonic booms?
In the update shared on the website, SpaceX emphasized the importance of reusability for achieving its long-term vision of making life multiplanetary.
“With each flight of Starship and the Super Heavy booster, we get closer to our goal of making life multiplanetary. The most important advancement to make this happen is full and rapid reusability of the entire launch system, operating Starship like an airplane which is fully and rapidly reusable after each flight,” the company stated.
The return of the Super Heavy booster to the launch site will produce sonic booms, described by SpaceX as “a brief, thunder-like noise” caused when an object travels faster than the speed of sound.
This phenomenon occurs as the vehicle slows down from supersonic speeds, resulting in pressure waves that reach the ground. SpaceX explains that the pressure change is “only a few pounds per square foot”, comparable to what one might experience when riding an elevator several floors.
The company further elaborated on the factors influencing the impact of sonic booms, such as the mass, shape, and size of the vehicle, as well as its altitude and flight path. Weather conditions also play a role in determining the intensity of the boom.
SpaceX stated that the effects of sonic booms are typically localized to the area directly beneath the vehicle, concentrated under its flight path and landing site.
SpaceX already gathered data
Historically, as SpaceX wrote, sonic booms in spaceflight have been associated with reusable vehicles, such as SpaceX’s Falcon rockets and NASA’s Space Shuttle. These booms are audible markers of the vehicle’s return from space and have been described as a double clap of thunder.
SpaceX gathered data from the first Super Heavy landing burn and splashdown during Starship’s fourth flight test. Those data suggest that while the Super Heavy’s sonic boom will be more powerful than those generated by Falcon landings, it poses “no risk of injury to those in the surrounding areas”.
The company assured that the strongest effects of the sonic boom would be confined to the vicinity of the Starbase launch pad, which is cleared before launches and designed to “withstand the environments of launching and returning the most powerful rocket ever flown”.
Each successful landing brings SpaceX closer to transforming space travel. The next Starship flight isn’t just a technical test; it marks a step toward the company’s goal of making life multiplanetary, and realizing dreams of exploring the Moon, Mars, and beyond.
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