Scientists describe seven stages of cosmic bodies turning into meteorites — ScienceDaily

Scientists analyzed videos and photographs of 75 recorded meteorite falls and identified seven stages that cosmic bodies pass through in Earth’s atmosphere before falling to Earth. As ScienceDaily reports, the study showed that the loss of mass by such bodies is primarily determined by melting and fragmentation, rather than simple evaporation.

At the first stage, the body forms a shock wave in front of itself, while its surface and the gas around it heat up and begin to glow. In denser layers of the atmosphere, the meteor’s brightness increases. Periodic changes in its glow may indicate rotation: among the fastest objects considered by the authors, one rotation took from 0.5 to 5 seconds.

Melting removes up to 40% of mass

At the bright fireball stage, melting becomes the main mechanism of material loss. The airflow strips molten particles from the surface, and after separating from the main body, they continue to evaporate. At an altitude of about 60 kilometers, melting reaches a relatively stable regime, while the fireball’s brightness either changes little or increases steadily.

According to the researchers’ estimate, melting alone can remove up to 40% of a cosmic body’s initial mass. The study’s lead author, meteor researcher and astronomer Peter Jenniskens of the SETI Institute and NASA Ames Research Center, noted that solid rocks do not simply evaporate from heating: they first melt and later fragment.

More current news is available on the UA.News Telegram channel Telegram.

Fragmentation begins earlier than previously believed

At the fifth stage, increasing air pressure causes cracks and the separation of fragments, which may be accompanied by repeated flashes. The authors found that fragmentation can begin when the pressure on the front of the body is only about one-fifth of the strength measured in meteorites found on Earth. Atmospheric heating and cracks from previous collisions in space may weaken the rock, according to the scientists.

If the rear part of the main fragment remains intact, it creates a low-pressure zone behind it that draws in smaller fragments. As a result, small meteorites may fall in a narrow strip. The final major fragmentation of the rear part is accompanied by a bright, predominantly red flash and a wider dispersal of fragments.

At the final stage, the fragments slow down enough to stop glowing. After melting ceases, a thin fusion crust remains on their surface, while atmospheric winds can shift the fall trajectory. The findings may also help study airbursts of larger asteroids: Jenniskens noted that the asteroid about 20 meters in diameter that caused the airburst over Chelyabinsk in 2013 went through the same stages.