Discoveries in the Sahara: Two Meteorites Linked to the Solar System’s Most Mysterious Rocky Planet

Researchers believe that two meteorites discovered in the Sahara Desert in 2023 might have originated from Mercury, the closest planet to the Sun. If confirmed, these would be the first known pieces of Mercury to reach Earth.

Mercury is often overlooked due to its proximity to the Sun, making it tough for spacecraft to study. Only two unmanned missions have visited it: Mariner 10 in 1973 and MESSENGER in 2004. A third mission, BepiColombo, is set to enter Mercury’s orbit in 2026.

Scientists have struggled to gather information about Mercury’s geology and surface composition. In contrast, there are over 1,100 known meteorites from the Moon and Mars. These meteorites are pieces that drifted to Earth after being ejected during asteroid impacts.

Not every planet can send debris our way. While Venus is closer to Earth, its heavy atmosphere may stop fragments from escaping its gravitational pull. Some astronomers believe that Mercury should still be able to produce meteors, though it’s more challenging due to its closeness to the Sun.

Ben Rider-Stokes, a researcher from the UK, notes that based on models, there should be about ten Mercury meteorites. Yet, since Mercury is so close to the Sun, any material ejected must break free from its gravity to reach Earth. This makes it harder, and none have been confirmed so far.

The two meteorites found—NWA 15915 and KG 022—could provide insights into Mercury if they’re proven to be from there. Rider-Stokes mentions some inconsistencies in their origin. For example, they seem to be older than materials found on Mercury’s surface.

Clues suggest these meteorites may share characteristics with Mercury. Previous candidates, like Northwest Africa 7325, failed to confirm links due to differing compositions. Recent studies have explored aubrites, but these also contradicted what was known about Mercury’s surface.

NASA’s MESSENGER probe provided most details about Mercury’s composition. The new meteorites contain minerals called olivine and pyroxene identified on Mercury, supporting their potential link. However, they lack plagioclase, believed to be dominant on Mercury’s surface.

The age of the meteorites raises questions. Rider-Stokes says they are 4.5 billion years old, while most of Mercury’s surface is about 4 billion years old. He still believes a connection could exist, as estimates on age are based on models that may not be completely accurate.

BepiColombo, launching in a couple of years, aims to uncover more about Mercury, including its formation and whether it has water. Understanding samples from other planetary bodies helps astronomers piece together the early solar system. Finding pieces from Mercury would be key since collecting samples directly from there is a costly and challenging task.

Sean Solomon, a lead researcher from the MESSENGER mission, has expressed doubts about the meteorites being from Mercury. He cites their early formation as a primary concern. Yet, he agrees that the meteorites have value. Their chemical traits hint at what materials Mercury might have originally formed from, suggesting that further study is necessary.

This discussion around the meteorites will continue among scientists. Rider-Stokes plans to share his findings globally, highlighting that until a definitive link is made or disproven, the debate will thrive within the planetary science community.

Understanding these meteorites could help reveal more about how Mercury formed and its place in the solar system’s history.



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planet Mercury, solar system, Martian meteorites, meteorite, surface of Mercury, Ben Rider-Stokes