(Web Desk) - How did life emerge on Earth? The age-old question has intrigued experts for years and now a study has hinted that rocky guests who visit us frequently might have carried the seeds of life.
Meteorites likely brought the building blocks of life to the primordial Earth from space, as per new evidence. Scientists are intrigued by the finding as this means that alien life exists somewhere in space.
The study says that these meteorites are the fractured remains of early "unmelted asteroids," a type of planetesimal, small rocky bodies considered the main building blocks of the planets in our solar system.
They came into existence around 4.6 billion years ago, forming in the disk of dust and gas around a young sun. Several particles swirled around our star which started to stick together eventually, adding more mass and making progressively larger bodies.
A team of researchers worked to determine the origin of Earth's "volatiles" and tracked the chemical element zinc in meteorites. They include six common chemicals vital for living things, including water.
"One of the most fundamental questions on the origin of life is where the materials we need for life to evolve came from," lead author of the study. Rayssa Martins, from the Department of Earth Sciences at the University of Cambridge in England, said in a statement.
"If we can understand how these materials came to be on Earth, it might give us clues to how life originated here and how it might emerge elsewhere," Martins added.
The team, including researchers from Cambridge and Imperial College London, decided to look for zinc because when it is formed in meteorites, it has a unique composition that can help understand about the origins of volatiles.
Earlier, the team found that zinc on Earth came from different regions of the solar system. Nearly half of it came from the inner region of the solar system. However, the rest of it likely originated from beyond Jupiter.
Planetesimals are of different types. Those that formed in the earliest era of the solar system were exposed to high levels of radiation from the infant sun. They lost volatiles through vaporisation because of melting due to the heat.
However, those that were born later weren't exposed to a lot of radiation, and so were held on to most of the volatiles. The team studied zinc in different meteorites originating from different planetesimals. They traced the arrival of zinc to Earth over tens of millions of years.
They found that melted planetesimals made up for around 70 per cent of our planet's total mass but only delivered about 10 per cent of its zinc content. This meant that 90 per cent of Earth's zinc originated from "unmelted" planetesimals.
Researchers believe that these unmelted space rocks likely also delivered a lot of volatiles to the forming Earth.