Jul 15, 2025 02:53 PM
Two meteorites found in the Sahara could be from the solar system’s least studied rocky planet, scientists say
https://edition.cnn.com/2025/07/14/scien...ara-desert
INTRO: Researchers suspect that two meteorites found in the Sahara Desert in 2023 may originally have come from Mercury, which would make them the first identified fragments of the solar system’s innermost planet.
The least studied and most mysterious of the solar system’s rocky planets, Mercury is so close to the sun that exploring it is difficult even for probes. Only two uncrewed spacecraft have visited it to date — Mariner 10, launched in 1973, and MESSENGER, launched in 2004. A third, BepiColombo, is en route and due to enter orbit around the planet in late 2026.
Scientists know little about Mercury’s geology and composition, and they have never been able to study a fragment of the planet that landed on Earth as a meteorite. In contrast, there are more than 1,100 known samples from the moon and Mars in the database of the Meteoritical Society, an organization that catalogs all known meteorites.
These 1,100 meteorites originated as fragments flung from the surfaces of the moon and Mars during asteroid impacts before making their way to Earth after a journey through space.
Not every planet is likely to eject fragments of itself Earth-ward during collisions. Though Venus is closer to us than Mars is, its greater gravitational pull and thick atmosphere may prevent the launch of impact debris. But some astronomers believe that Mercury should be capable of generating meteors.
“Based on the amount of lunar and Martian meteorites, we should have around 10 Mercury meteorites, according to dynamical modeling,” said Ben Rider-Stokes, a postdoctoral researcher in achondrite meteorites at the UK’s Open University and lead author of a study on the Sahara meteorites, published in June in the journal Icarus.
“However, Mercury is a lot closer to the sun, so anything that’s ejected off Mercury also has to escape the sun’s gravity to get to us. It is dynamically possible, just a lot harder. No one has confidently identified a meteorite from Mercury as of yet,” he said, adding that no mission thus far has been capable of bringing back physical samples from the planet either.
If the two meteorites found in 2023 — named Northwest Africa 15915 (NWA 15915) and Ksar Ghilane 022 (KG 022) — were confirmed to be from Mercury, they would greatly advance scientists’ understanding of the planet, according to Rider-Stokes. But he and his coauthors are the first to warn of some inconsistencies in matching those space rocks to what scientists know about Mercury.
The biggest is that the fragments appear to have formed about 500 million years earlier than the surface of Mercury itself. However, according to Rider-Stokes, this finding could be based on inaccurate estimates, making a conclusive assessment unlikely. “Until we return material from Mercury or visit the surface,” he said, “it will be very difficult to confidently prove, and disprove, a Mercurian origin for these samples.”
But there are some compositional clues that suggest the meteorites might have a link to the planet closest to the sun... (MORE - details)
https://edition.cnn.com/2025/07/14/scien...ara-desert
INTRO: Researchers suspect that two meteorites found in the Sahara Desert in 2023 may originally have come from Mercury, which would make them the first identified fragments of the solar system’s innermost planet.
The least studied and most mysterious of the solar system’s rocky planets, Mercury is so close to the sun that exploring it is difficult even for probes. Only two uncrewed spacecraft have visited it to date — Mariner 10, launched in 1973, and MESSENGER, launched in 2004. A third, BepiColombo, is en route and due to enter orbit around the planet in late 2026.
Scientists know little about Mercury’s geology and composition, and they have never been able to study a fragment of the planet that landed on Earth as a meteorite. In contrast, there are more than 1,100 known samples from the moon and Mars in the database of the Meteoritical Society, an organization that catalogs all known meteorites.
These 1,100 meteorites originated as fragments flung from the surfaces of the moon and Mars during asteroid impacts before making their way to Earth after a journey through space.
Not every planet is likely to eject fragments of itself Earth-ward during collisions. Though Venus is closer to us than Mars is, its greater gravitational pull and thick atmosphere may prevent the launch of impact debris. But some astronomers believe that Mercury should be capable of generating meteors.
“Based on the amount of lunar and Martian meteorites, we should have around 10 Mercury meteorites, according to dynamical modeling,” said Ben Rider-Stokes, a postdoctoral researcher in achondrite meteorites at the UK’s Open University and lead author of a study on the Sahara meteorites, published in June in the journal Icarus.
“However, Mercury is a lot closer to the sun, so anything that’s ejected off Mercury also has to escape the sun’s gravity to get to us. It is dynamically possible, just a lot harder. No one has confidently identified a meteorite from Mercury as of yet,” he said, adding that no mission thus far has been capable of bringing back physical samples from the planet either.
If the two meteorites found in 2023 — named Northwest Africa 15915 (NWA 15915) and Ksar Ghilane 022 (KG 022) — were confirmed to be from Mercury, they would greatly advance scientists’ understanding of the planet, according to Rider-Stokes. But he and his coauthors are the first to warn of some inconsistencies in matching those space rocks to what scientists know about Mercury.
The biggest is that the fragments appear to have formed about 500 million years earlier than the surface of Mercury itself. However, according to Rider-Stokes, this finding could be based on inaccurate estimates, making a conclusive assessment unlikely. “Until we return material from Mercury or visit the surface,” he said, “it will be very difficult to confidently prove, and disprove, a Mercurian origin for these samples.”
But there are some compositional clues that suggest the meteorites might have a link to the planet closest to the sun... (MORE - details)