Could an asteroid help us understand how planets and our solar system formed? Very likely! Samples collected from the asteroid Ryugu are revealing new evidence of a primordial magnetic field that is believed to have helped asteroids, planets and moons develop in our solar system.
Scientists analyzed a sample brought back to Earth by the mission Hayabusa2, and discovered evidence of an ancient magnetic field preserved in the asteroid's geological record.
Elias Mansbach, lead author of the new study, explained that this nebulous field disappeared about three to four million years after the formation of the solar system and is thought to have played an important role in the early formation of planets. However, we don't know exactly how far this magnetic field extended and what role it played in more distant regions, because there haven't been many samples that could give us evidence of the outer solar system.
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Astronomers believe that the asteroid Ryugu formed in the outer reaches of our solar system nearly four billion years ago and then moved closer to the sun. Eventually, it settled into its current orbit between Earth and Mars. This means that the asteroid has not been particularly affected by processes that alter or erase geological and magnetic records, and so has preserved ancient magnetic signatures.
To determine the presence of a magnetic field, samples of the asteroid are placed in a device called a magnetometer. Depending on the result, it can be seen whether the asteroid was exposed to a magnetic field at some point in its history, allowing scientists to determine whether an ancient magnetic field was present when the asteroid formed.
The research team then applied an alternating magnetic field to gradually demagnetize each sample, which helps identify the original magnetic signal stored in the particles. This process removes weaker, more recent magnetic fingerprints and leaves only the stronger, more ancient magnetization intact.
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Our solar system formed from a dense cloud of gas and dust that collapsed into a swirling disk of matter, most of which was drawn to the center of the disk – which would eventually become the sun. The rest remained a swirling nebula of ionized gas.
Scientists believe that there was a magnetic field between the newly formed sun and the swirling outer gases. This field likely helped drive matter into the solar system, where it was incorporated into planets, asteroids, and moons.
The research team analyzed three particles returned from the asteroid Ryugu. They found evidence of a very weak field that existed less than three million years after the formation of the solar system.
"Furthermore, we reexamine previous paleomagnetic reports from three other distant meteorites and show that a field was indeed present at that time, although it was weak (10 times less than Earth's field)," the researchers said.
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Taken together, the analysis of these three meteorites and the Ryugu samples suggests the existence of a weak magnetic field. Despite its weakness, this field was likely strong enough to facilitate mass transfer at rates similar to those in the inner solar system.
The study of asteroids and comets is very important, since their composition and evolution help us understand more about the formation of planets and moons, how water came to Earth's oceans, and how life managed to arise from organic compounds and other chemicals that were transported to Earth.
Source: www.space.com
