On its second flight, SpaceX’s Starship reached space for the first time before exploding. The massive blast created supersonic shock waves that opened an unprecedented hole in the ionosphere, a part of the atmosphere where air coexists with free ions and electrons due to solar radiation.
Two high-altitude explosions. On Nov. 18, 2023, Starship successfully lifted off and separated from its booster at an altitude of 56 miles. Shortly after that, the thruster exploded. The spacecraft reached an altitude of 93 miles and burst while flushing out liquid oxygen.
The destruction of the megacraft created one of the largest holes ever recorded in the ionosphere, the ionized layer of the upper atmosphere. According to Russian researchers in a paper published in Geophysical Research Letters, the hole reached a size of thousands of miles and remained for nearly an hour.
A significant disturbance in the ionosphere. Led by atmospheric physicist Yury Yasyukevich of the Irkutsk Institute of Solar-Terrestrial Physics, the researchers analyzed public data from more than 2,500 ground-based GNSS stations for changes in the ionosphere.
Free electrons affect the propagation of radio waves emitted by navigation satellites, which is why these receivers detect holes in the ionosphere. And that’s what happened. Scientists found a huge V-shaped disturbance that propagated northward after Starship’s flight. This was a surprise because these disturbances usually move south, guided by the magnetic field.
Supersonic shock waves. By measuring the cone angle of the disturbance, the scientists found a match with the supersonic speed at which Starship was traveling. As such, the acoustic shock waves generated by the spacecraft were the likely cause of the disturbance.
The spacecraft exploded as it was about to initiate a suborbital trajectory at over 13,000 miles per hour. The shock waves from the explosion, added to those from the fuel, caused an exceptional reduction in the electron content of the ionosphere.
An unprecedented hole. The disturbance in the ionosphere became visible 8 minutes after the spacecraft’s launch. It spread to about 1,200 miles north of the site of the explosions.
Scientists have never observed an ionospheric disturbance of this amplitude and oscillation before, which makes sense since Starship is the largest rocket ever developed. But what’s truly unusual is that the fuel’s chemical reaction didn’t cause the hole. The potent shock waves generated by the explosion created it.
Uncharted territory. According to the study, this is the first time a group of scientists has detected a non-chemical ionospheric hole caused by a space launch. The hole wasn’t as large as the one caused by the eruption of a volcano in Tonga in early 2022 or the meteorite that fell near Chelyabinsk, Russia, in 2013. However, these are natural events, not anthropogenic ones, such as those caused by SpaceX’s spacecraft.
The research provides new insights into how Starship’s monumental size can unexpectedly affect the upper atmosphere. On its third flight, it exploded at an altitude of 40 miles during re-entry over the Indian Ocean. On its fourth, it successfully splashed down, albeit a little burned.
Image | SpaceX
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