Mar 12, 2021

Cosmic Relic: In Sahara, Researchers Unearth Ancient Meteorite that Predates Earth Itself


Home delivered to us due to Earth’s gravity, meteorites are always a treasure trove for researchers trying to decipher the cosmic world. But finding an extremely old meteorite from the formative years of the solar system is a jackpot that a team of researchers wandering in the Sahara Desert hardly expected.

A team led by researchers from Centre National de la Recherche Scientifique (CNRS), France, have discovered an ancient meteorite in the Sahara desert, which predates our home planet Earth. This meteorite dates back to approximately 4.56 billion years, while our planet is of roughly 4.54 billion years of age, making it the oldest primaeval space rock to have ever unearthed.

The volcanic rock, named Erg Chech 002 (EC 002), was spotted by scientists in May 2020 from Adrar in the Algeria region of the Sahara desert. Researchers describe the discovery as an extremely rare relic of the ancient cosmic world.

A rare meteorite

The meteorites are mainly debris of asteroids that originate in outer space, get attracted towards Earth due to gravity, survive its passage through Earth’s atmosphere to finally crash on the surface. Studying them gives insights into the early history of our solar system.

The Lunar and Planetary Institute (LPI) describes the meteorite EC 002 as “relatively coarse-grained, tan and beige appearance with sporadic larger green, yellow-green and less commonly yellow-brown crystals (up to 9 cm by 4 cm in some specimens).”

The texture of the meteorite indicates that it was formed from molten rock or magma, which means that this is a type of andesite rock. Soon after its discovery, researchers realised that the meteorite is very unique since most meteorites that fall on Earth are made of basalt. However, the andesite-rich meteorites have been recently discovered in 2009 and in 2017.

“Protoplanets covered by andesitic crusts were probably frequent. However, no asteroid shares the spectral features of EC 002, indicating that almost all of these bodies have disappeared, either because they went on to form the building blocks of larger bodies or planets or were simply destroyed,” reads the research paper.

Origin of EC 002

The researchers have identified that the newly discovered meteorite belongs to a protoplanet—a large, rocky body that is yet to develop into a planet. The protoplanet was believed to be forming when the solar system was just 2 million years old. However, the baby planet probably couldn’t survive the violent early phase of the solar system when bigger rocky planets like Earth, Mars, Venus and Mercury prevailed.

The radioactive versions or isotopes of aluminium and magnesium describe the meteorite's parent body. The rare meteorite from Sahara is classified as an achondrite type of meteorite that forms in the differentiated parent body—the ones with distinct core and crust.

For EC 002, the parent body crust is noted to be rich in silica, while magma (hot fluid) from which this rock formed is estimated to be as hot as 1,220°C. The iron-rich magma is likely to have taken at least 1,00,000 years to cool and solidify. Moreover, one other trait of such ancient meteorites is the absence of chondrules—a grain-like material of partially molten droplets—which form during the merger of the rocky bodies in space.

Our solar system was unimaginably chaotic during the time of planetary formation. Small masses, which escaped the volatile consolidation into a planet, formed relatively smaller chunks of space rocks called asteroids. Scientists today spend years studying these space rocks to understand how our solar system formed. It is also believed that meteorites could have delivered organic compounds, which led to the origin of life on Earth.

The study will be published in the journal PNAS next week, but is available online and can be accessed here.

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