It is estimated that about 44,000 to 84,000 metric tons of meteoritic material fall on Earth each year. However, the vast majority of this material is in the form of tiny dust particles that burn up in the atmosphere and never reach the ground.
In terms of actual meteorites, which are meteoroids that survive their passage through the atmosphere and impact the Earth’s surface, it is estimated that around 500 to 1000 meteorites larger than 10 grams fall on Earth every year. Most of these meteorites are small and fall in remote areas, such as oceans or uninhabited regions, so they often go unnoticed.
You got the point: there are numerous meteorites falling on our planet.
Eyes set on the Winchcombe meteorite
The Winchcombe meteorite, a rare type of meteorite that fell to Earth in 2021, has revealed that there may be no such thing as a “pristine” meteorite. Changes to the rock’s chemistry occurred within just a few hours of entering Earth’s atmosphere, causing significant contamination from the terrestrial atmosphere and ground. ScienceAlert brings the details regarding the discovery.
The findings could help protect newly fallen meteorites and geological samples brought home from space from terrestrial alteration. The meteorite’s fusion crust was found to have calcite and calcium sulfates formed on it, likely due to damp environments, suggesting that meteorites should be carefully stored to minimize contamination.
Laura Jenkins, an Earth scientist from the University of Glasgow, explained:
The Winchcombe meteorite is often described as a ‘pristine’ example of a CM chondrite meteorite, and it’s already yielded remarkable insights,
However, what we’ve shown with this study is that there’s really no such thing as a pristine meteorite – terrestrial alteration begins the moment it encounters Earth’s atmosphere, and we can see it in these samples which we analyzed just a couple of months after the meteorite landed.
The new study appears in Meteoritics & Planetary Science.