A brilliant white stripe appeared in the US sky on May 17, catching skywatchers off guard. Initially, scientists thought it was a STEVE (Supernumerary Traction Enhanced Velocity Exclusion) event, but further investigation revealed that the light was actually caused by a rocket stage dumping fuel into space.
LandSpace Technology’s Zhuque-2E Y2 methane-fueled carrier rocket launched six satellites into orbit at 04:12 UTC on May 17. A short time later, the white stripe appeared in the sky, with experts pinpointing it as the result of the rocket’s upper stage releasing methalox fuel into the ionosphere.
Methalox is a type of rocket fuel made from methane and liquid oxygen that has gained attention for its potential benefits, including being cheaper, cleaner, and easier to store. Its use could make crewed missions to Mars more efficient by eliminating the need to carry fuel on the return journey.
Rocket fuel can glow in the upper atmosphere through several mechanisms, one of which involves chemical reactions between the fuel and ionospheric molecules. This reaction produced the brilliant white stripe seen in the sky.
While this phenomenon is rare, it highlights the increasing use of methalox rocket fuel and its potential for future space missions.
Source: https://www.sciencealert.com/bright-streak-appears-over-us-during-aurora-storm-mystifying-skywatchers