It is the oldest meteorite ever found, dating back almost 4.6 billion years to a time when the Earth didn’t even exist.
Now, space rock Erg Chech 002 is shedding new light on what our early system looked like — and the revelations are not what scientists expected.
A team of Australian researchers say their study brings into question the accuracy of how experts calculate the age of meteorites, suggesting that some may not be as old as first thought.
That’s because they found that EC 002 contained more of the radioactive isotope Aluminium-26 (26Al) than other ancient achondrites, or stony meteorites, of a similar age.
This is significant because it challenges the theory that 26AI – which is thought to provide a heat source for the building blocks of planets – was distributed evenly throughout the early solar system.
Oldest meteorite ever found: Space rock Erg Chech 002 (pictured) is shedding new light on what our early system looked like — and the revelations are not what scientists expected
The meteorite was discovered in 2020 in the Erg Chech region of the Sahara Desert in Algeria
Experts estimate the age of meteorites based on the amount of 26AI present in them when they were formed.
But if the isotope was distributed unevenly throughout the early solar system, as the new study suggests, then it cannot be relied upon to give an accurate indication of how old a space rock is or what role it might have played in planet formation.
That is at odds with previous research which suggested 26AI was evenly spread in the lead up to the formation of planets such as Earth.
We know that our solar system was formed around 4.5 billion years ago from a collapsing cloud of interstellar gas and dust which was likely part of a much larger nebula.
Scientists think its collapse may have been triggered by the shockwave of a nearby supernova, or exploding star, which in turn led to the creation of a solar nebula — a spinning, swirling disk of material from which the solar system originated.
26AI was then vital in the process that led to us walking on Earth today because it provides enough heat through radioactive decay to produce planetary bodies with layered interiors such as ours.
It also helps dry out early planetesimals to produce water-poor, rocky planets.
Due to its very short half-life of about 770,000 years, scientists think 26AI must have been formed or mixed into the young sun’s surrounding planet-forming disk shortly before the condensation of the first solid matter in our solar system.
Its existence in EC 002 therefore provides an opportunity to further explore the initial distribution of the isotope before the Earth was formed.
Whether the isotope was distributed evenly throughout the early solar system is important in determining the age of meteorites.
Researchers at the Australian National University, led by Evgenii Krestianinov, analysed EC 002 and determined its lead-isotopic age to be about 4.566 billion years old.
The rock consists mostly of volcanic rock, leading experts to believe it came from the crust of a very early planet
They combined this finding with existing data for this meteorite and compared it with other very old meteorites that crystallised from melts.
The researchers demonstrated that 26Al had an uneven distribution within the early solar nebula.
For this reason, they said meteorite chronology studies should be cautious and take a generalised approach to dating with short-lived isotopes that account for their uneven distribution.
This, the researchers added, would improve the accuracy and reliability of determining the ages of meteorites and planetary materials.
‘Developing a generalised approach for isotopic dating with Al-Mg and other extinct isotope chronometers that accounts for heterogeneous distribution of the parent radionuclide would allow to produce more accurate and reliable age data for meteorites and asteroidal and planetary materials to advance a better understanding for the formation of our solar system,’ the authors wrote.
The meteorite was discovered in 2020 in the Erg Chech region of the Sahara Desert in Algeria.
It consists primarily of volcanic rock, leading experts to believe it came from the crust of a very early planet.
A previous study found that the rock was once liquid lava but cooled and solidified over 100,000 years to form the 70-pound piece that eventually made its way to our planet.
No asteroids have been found with similar properties, which suggests the protoplanet it came from has since disappeared by either becoming parts of larger bodies or ‘was simply destroyed’, the researchers said.
Among the other oldest achondrites previously found include NWA 1111942, which is estimated to be about 4.565 billion years old, and the 4.564 billion-year-old Asuka 88139427.
The new study has been published in the journal Nature Communications.
