Rocket fuel reactions cause unprecedented 'SpaceX Auroras' in sky

Space rocket launches invariably produce undesired effects. Notably, they cause the development of ionospheric holes. As spacecraft traverse the atmosphere, they continuously eject fuel. Upon reaching the ionospheric layer, the fuel dosage triggers a reaction involving ionized oxygen atoms, which transform into gas molecules and emit red light. This occurrence is quite similar to polar auroras, but only transpires on a relatively small scale.

Within SpaceX's operations, this artificial aurora happens twice. Elon Musk's company employs reusable rockets. The Falcon 9 rockets, which currently convey dozens of Starlink satellites, traverse the ionosphere not just during the ascent stage, but also on return.

During their journey, the secondary burners of these rockets discharge additional fuel, which also results in the formation of an ionospheric gap. Although this gap is transient and persists for a shorter duration compared to the event accompanying the launches, the red spot it produces in the sky is distinctive and frequent. Consequently, astronomers have christened it the "SpaceX Aurora".

The "SpaceX Aurora" was initially documented in February of the present year. Yet, with the continuous expansion of the Starlink constellation, this phenomenon has escalated. As of the fall of 2023, astronomers are already witnessing 2 to 5 auroras each month. Reports from the Texas McDonald Observatory state that these auroras are highly luminous and discernible to the naked eye.

The service Spaceweather.com corroborates the claim that "SpaceX Auroras" are easily identifiable. They become visible approximately 90 minutes after each subsequent Starlink series launch. At this point, the Falcon 9 rocket is on its way to splash down in the Atlantic, at an altitude of about 186 miles from Earth. Currently, however, "SpaceX Auroras" only transpire over the south-central region of the United States.

Ionospheric gaps, regardless of how they are generated, pose no harm to humans or the environment. Conversely, they can disrupt short-wave radio communication and affect GPS signals. In the context of "SpaceX Auroras", the frequency of such disruptions is increasing.

Although Falcon 9 rockets do not launch daily—about once a week on average—astronomers report encountering problems due to their frequency. Concerns arise regarding whether such recurrent ionospheric gaps might compromise their observations. This issue goes beyond simple amateur stargazing; it affects extensive research studies that carry profound implications for astrophysics and the entire space industry.

"SpaceX Auroras" are not the only light spectacles provided by Elon Musk's enterprise. Bright trails that accompany SpaceX launches are termed "SpaceX Trails".

Rocket boosters utilized by SpaceX also expel fuel into space, which forms a cloud of ice crystals. When hit by sunlight and reflected towards Earth, they can fashion brilliant spirals in the night sky, a phenomenon known as the "SpaceX Spiral".

The "SpaceX Spiral" occurrence was observed multiple times this year. Initially sighted on the Hawaiian island of Mauna Kea, it was later spotted by Alaskan residents in April.