SpaceX launch last year punched huge, temporary hole in the ionosphere

Contrary to popular belief, most of the time when a rocket launches, it does not go straight up into outer space. Rather, shortly after launch, most rockets will begin to pitch over into the downrange direction, limiting gravity drag and stress on the vehicle. Often, by 80 or 100km, a rocket is traveling nearly parallel to the Earth’s surface before releasing its payload into orbit.

However, in August of last year, a SpaceX Falcon 9 rocket launch from California did not make such a pitch over maneuver. Rather, the Formosat-5 mission launched vertically and stayed that way for most of its ascent into space. The rocket could do this because the Taiwanese payload was light for the Falcon 9 rocket, weighing only 475kg and bound for an orbit 720km above the Earth’s surface.

As a result of this launch profile, the rocket maintained a nearly vertical trajectory all the way through much of the Earth’s ionosphere, which ranges from about 60km above the planet to 1,000km up. In doing so, the Falcon 9 booster and its second stage created unique, circular shockwaves. The rocket launch also punched a temporary, 900-km-wide hole into the plasma of the ionosphere.

Circular shock waves

Scientists used to think the Sun’s radiation dominated the Earth’s extremely tenuous atmosphere in the ionosphere, but in the last decade they have begun to understand that weather at the planet’s surface can also change conditions far above. Researchers are increasingly interested in the effects of rockets, too. This is because disturbances in the ionized and neutral particles of the ionosphere have consequences for satellites, such as causing errors in Global Positioning System navigation.