Similarly,
We may have finally found:
The meteorites fascinate. Therefore, as well by their beauty, when one thinks of pallasites with their crystals ofolivineolivine In an iron matrix, only by their origin, both the interplanetary space and the dawn of the formation of the solar system. However, Our knowledge of these rocks is recent. Furthermore, even if humanity has faced these stones that have fallen from the sky for millennia.
This extraterrestrial provenance is the physicistphysicist et mathematicianmathematician Jean-Baptiste BiotJean-Baptiste Biot Who. Moreover, for the first time, gave evidence in 1803, following the fall of the meteorite of the eagle into the Orne. However, But it is really during the second half of the XXe century that the study of meteorites will leaps. Furthermore, accompanying the progress we may have finally found of cosmochemistry and cosmogony of the solar system, and the revolution astronauticsastronautics At the origin of the missions ApolloApollo and travel.
Meteorite hunter: All about meteorites: episode 1. Moreover, © Louis Carion
A rich meteorite zoo – We may have finally found
More than 40. Therefore, 000 meteorites are known today and they are very diverse, although large families have been defined. Moreover, The best known are the chondriteschondritesTHE achondritesachondrites and sideriessideries which, as their name suggests, contain a lot of iron.
Chondrites. In addition, like the famous Allendes and Murchison, are very primitive objects that are considered as formed basic materials of rocky bodies, some of which will become planets.
Achondrites are stony. Meanwhile, their characteristics are explained by considering them as fragments of body sufficiently massive to have we may have finally found differentiated themselves like the earth. Nevertheless, They must therefore come from celestial bodies whose sizes are quite large – for example several hundred kilometers – for theaccretionaccretion. Meanwhile, the quantity of radioactive elements contained initially are such that the heatheat released led to a partial fusionpartial fusion rocks and their modification. Furthermore, Which led to the formation of an iron heart. Meanwhile, nickelnickel in depth and, on the surface, volcanic eruptionsvolcanic eruptions of materialsmaterials Ignied.
We have thus found meteorites for a long time whose composition resembles that of basaltsbasalts Known on earth (but with notable differences anyway). They therefore come from volcanoesvolcanoes we may have finally found Surchase on small planetssmall planetstoday disappeared in collisions. and having left vestiges in the asteroid beltasteroid belt that they populated, coming from different regions of the solar system, very likely as a result of planetary migrations.
Meteorite hunter: All about meteorites: episode 2. © Louis Carion
Origins studied with cosmochemistry
The most fascinating embroidered meteorites have been those that. in recent decades, we have managed to attribute to anything less than the LuneLune And March!
In the case of the Moon. this attribution was facilitated by the fact that we had already brought back to earth not far from 382 kilogramskilograms lunar rocks, whose composition has been studied finely in the laboratory. The rapprochement with certain meteorites was therefore without big problem.
Both in the case of March. the moon, we may have finally found we always involve impacts of small celestial bodies powerful enough to eject in the space of fragments of crustcrust death AstresAstres. Additionally, The attraction of SoleilSoleil Or the earth ending up bringing them to collide with our blue planet.
One of the keys to the identification of Martian meteorites has based on the analysis of the composition of theatmosphereatmosphere tenuous of March by missions VikingViking in the 1970s. Bubbles of gazgaz With the same characteristic composition were thus found in the meteorites attributed today to the red planet.
What about mercury meteorites?
We can naturally ask the question of the existence of meteorites which would have come from VenusVenus. even we may have finally found MercureMercureaccording to the same scenario as for the origin of Martian and lunar meteorites. In fact, a publication dating about 15 years suggests that mercurian meteorites could be found on earth.
Better still. a few candidates had even been then offered such as the Northwest Africa meteorite (NWA) 7325 or even the Aubritis, which are a group of meteorites of the Achondritis type, named after a small meteorite that has fallen in 1836 in Aubres, near Nyons in France.
But. in both cases, these hypotheses were questioned, in particular after the best knowledge of the surface composition of mercury provided by the mission MessengerMessenger of the NasaNasa.
A new hope was born recently. as explained, in The Conversationan article by Ben Rider-Stokes, postdoctoral researcher in meteorite meteorite at theOpen University (United Kingdom). He is his we may have finally found colleagues think he has identified two new meteorites. Ksar Ghilane 022 and Northwest Africa 15915, which appear to be promising!
In the article of The Conversation. Ben Rider-Stokes Explique: « The two meteorites contain olivine and pyroxenepyroxeneas well as a small amount of albitic plagioclase and oldhamite. These characteristics agree with the predictions concerning the composition of the Mercury surface. These common characteristics make these samples convincing candidates for the formation of mercurian materials.
However, notable differences exist. The two meteorites contain only traces of plagioclase, unlike the surface of mercury, which contains more than 37 %. In addition, our study suggests that samples have about 4 528 million years. This figure is significantly higher than that of the oldest recognized surface units of mercury. estimated (according to the counting of craters) at around 4 000 million years.
If these meteorites come from mercury. they could represent ancient we may have finally found materials which are no longer preserved in the geologygeology current surface of the planet. »
We may know more with the data from the Bepicolombo mission!
The Euro-Japanese mission, Bepicolombo, started to attack Mercury in 2018. Objective? Study from 2025. the surface and internal structure of the small rocky planet, closest to the sun, but also learn about its magnetosphere and its magnetic field. © CNES
Did you know?
We know more than 350 Martian meteorites which are essentially divided between three major classes called from the. names of the villages near which Homo sapiens wise attended their fall. There was thus that observed near the French village of Chassigny in 1815. that of Shergotty in India (1865) and finally that of Nakhla in Egypt (1911). The meteorite Black Beauty is still atypical we may have finally found with regard to this classification.
These are often ignful rocks which have therefore formed from the cooling of a magma. for example in the form of a lava on the surface of Mars, but also in its coat. The impact of a small celestial body would have been powerful enough each time to eject in the space. of Mars fragments bearing these rocks which are often collectively designated under the term SNC (for Shergottite Nakhlite Chassignite).
We may have finally found
Martian atmosphere bubbles
In some cases. gas bubbles have been found in these fragments found on earth, the composition of which was close to that of the Martian atmosphere known from the Viking missions and which cannot be air bubbles trapped by the meteorite. This is one of the reasons that suggest that we are in the presence of natural samples from the. red planet on our blue planet.
Thus. the D/H ratio between we may have finally found the well -known isotopes of hydrogen, the deuterium D whose nucleus is composed of a proton and a neutron while the nucleus of the isotope H does not contain neutron, is very different from that of the earth’s atmosphere. It is higher because lighter atoms go more easily in space than the heaviest. so that by largely losing its atmosphere (and its water) under the effect of the solar wind and because of its weak gravity, the planet Mars ended up with a more important D/H ratio.
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