Most metstones that reach Earth come from the asteroid belt between Mars and Jupiter. However, there are around 1,000 met stones that come from the moon and Mars. This is probably the result of an asteroid hitting its surface and ejecting material towards the planet.
It should also be physically possible for such debris to reach Earth from mercury. But so far, it has not been confirmed to come from it. It presents a mystery for many years.
A new study conducted by my colleague and I discovered two metstones that could have Mercurian origins. If confirmed, they could provide an unusual window into Mercury’s formation and evolution, potentially reconstructing understanding of the planets closest to the Sun.
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Mercury is very close to the Sun, so space missions to obtain samples from it are complicated and expensive. Therefore, naturally delivered fragments may be the only practical way to directly study their surfaces. Such discoveries are scientifically invaluable.
Observations from NASA’s messenger mission inferred the surface composition of mercury. This suggests the presence of minerals known as sodium-rich plagioclase (such as part-time jobs), iron-poor pyroxines (such as enstite), iron-deficient olivines (such as forsterite), and sulfide minerals such as aldahamite.
The Meteorite Northwest Africa (NWA) 7325 was initially proposed as a fragment of mercury. However, its mineralogy contains chromium-rich pyroxenes, which contain around 1% iron. This is insufficient to the estimated surface composition of Mercury. As a result of this and other factors, this link is being challenged.
Related: Mercury may have “potentially habitable” areas beneath the surface, suggesting salty glacier
Orbright metstones have also been proposed as potential mercury fragments. Recent modelling of formation suggests origins from large planetary bodies with a diameter of about 5,000 km (similar to mercury) about 5,000 km, which may support this hypothesis.
Orbrites do not show surfaces and chemical or spectra of mercury (a study of how light is decomposed by wavelengths), but there is a hypothesis that they may originate from the shallow mantle (the layer below the surface) of the planet. Despite continuous research, the existence of a conclusive metstone from mercury has not been proven.
Our latest study investigated the properties of two unusual metstones, the Ksar Ghilane 022 and the Northwest Africa 15915. We found that the two samples appear to be related. Their mineral and surface composition also shows interesting similarities to the mercury crust. Therefore, this led us to speculate about the possible origins of Mercuru.
Both metstones contain olivine and pyroxene, mild albity plagioclase, and allhamite. These features are consistent with predictions of mercury surface composition. Furthermore, their oxygen composition matches the composition of aub dye. These shared properties force the sample to force candidates into candidates.
However, there are significant differences. Both metstones contain only trace amounts of agricultural quantities, in contrast to the surface of mercury, which is estimated to contain more than 37%, as opposed to the surface of mercury. Furthermore, our study suggests that the sample age is approximately 4,528 million years old. This is significantly older than the oldest surface units of mercury, and is based on crater counts) is projected to be around 4,000 million years.
If these metstones are derived from mercury, they may represent early materials that are no longer preserved in the planet’s current surface geology.
Have we ever known?
To link any metstone to a particular asteroid shape, the moon or planet is very challenging. For example, laboratory analysis of Apollo samples allowed the met stones found on desert collection expeditions to match the lunar material. Mars’ metstones are identified by similarities between compositional compositions of metstones in measurements of Mars’ atmosphere by spacecraft.
It is very difficult to assess the Met Stone Planet Link until you visit mercury and retrieve the material.
The Bepicolombo Space Mission by European and Japanese space agencies is currently in orbit around mercury, and is about to send back high-resolution data. This may help determine the ultimate origin of Ksar Ghilane 022 and Northwest Africa 15915.
If mercury metstones are discovered, they will help you solve various long-standing scientific questions. For example, they were able to reveal the age and evolution of Mercury’s crust, its mineralogical and geochemical composition, and its gas properties.
The origins of these samples may continue to be the subject of ongoing debate within the scientific community. Several presentations have already been scheduled for the 2025 Meteorical Society Meeting in Australia. We look forward to future discussions that will further explore and improve our understanding of potential origins.
For now, all we can do is make educated speculations. What do you think?
This edited article will be republished from the conversation under a Creative Commons license. Please read the original article.
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