Experts from the SETI Institute and NASA’s Ames Research Center have described how space objects change as they pass through Earth’s atmosphere. Scientists analyzed photographic and video footage of 75 meteorite falls. Their work helped clarify how the composition of a celestial body influences its fragmentation and mass loss.
The researchers identified seven sequential stages: atmospheric entry; the onset and intensification of luminosity; the formation of a fireball; the beginning of melting; and the fragmentation of the object’s leading section followed by its trailing section. Subsequently, fragments continue to melt and break apart until the light fades, after which air currents scatter the crust-covered remnants. The study’s findings have been published in the journal Meteoritics & Planetary Science.
The authors concluded that rocky bodies do not simply vaporize due to heat in the atmosphere. According to lead author Peter Jenniskens, melting occurs first, followed by fragmentation, which drives the loss of mass. The altitude at which each of the seven phases occurs depends on the meteorite’s composition.
The data obtained could prove useful for developing planetary defense measures and preparing for potential airbursts caused by space objects. Scientists cite the fireball that flew over Chelyabinsk on February 15, 2013, as a notable example. An asteroid measuring approximately 20 meters entered the atmosphere at a speed of 19 km/s and disintegrated at an altitude of roughly 30 kilometers.
The energy of the explosion over the Chelyabinsk region was estimated to be approximately 30 times greater than that of the bomb dropped on Hiroshima. About 1,500 people were injured, primarily by glass shards from windows shattered by the blast. More than 7,200 buildings across six cities sustained damage. Scientists also recalled the Tunguska event of June 30, 1908. They estimate that the bolide measured between 50 and 100 meters in size and that the explosion occurred at an altitude of 5 to 10 kilometers. The shockwave knocked down approximately 80 million trees across an area exceeding 2,150 square kilometers.
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