How did life come to Earth? Scientists reveal new data

A new analysis has found that dust grains on the asteroid Bennu contain key chemical elements needed for life. Samples of the space rock, brought back to Earth by a NASA spacecraft, contain a variety of minerals and thousands of organic compounds.

These samples also include amino acids, the molecules that make up proteins, as well as nucleobases, the building blocks of DNA.

Although this does not mean that there is life on Bennu, the discovery supports the theory that asteroids brought vital ingredients to Earth by colliding with our planet billions of years ago.

Scientists believe that these compounds could be transported to other worlds within our solar system, opening the way to studying the possibilities of life in different places.

“What we have discovered is amazing,” said Professor Sarah Russell, a cosmic mineralogist at the Natural History Museum in London. “These discoveries contribute to our understanding of our origins and help us answer the big questions about where life began. Who doesn’t want to know how life began?”

These results were published in the journal Nature.

Collecting parts of the asteroid Bennu is considered one of the most daring and important missions carried out by NASA in its history. The agency sent a spacecraft called "Osiris-Rex" equipped with a robotic arm to pick up some rocks from the asteroid with a diameter of 500 meters, then packed them in a capsule and returned to Earth in 2023.

About 120 grams of black dust was collected and shared with scientists around the world, and although this amount may seem small, it proved to be a "valuable treasure."

"Each grain tells us something new about Bennu," said Professor Russell, who was studying the tiny grains.

A teaspoon of asteroid dust was sent to scientists in the UK.

The new research also showed that the space rock Bennu is rich in nitrogen and compounds that contain high amounts of carbon.

These samples include 14 of the 20 amino acids that life on Earth uses to build proteins, as well as all four circular molecules that make up DNA: adenine, guanine, cytosine and thymine.

The study also revealed a range of minerals and salts, indicating the presence of water on the asteroid. In addition, ammonia, a key material for biochemical reactions, was found in the sample.

Some of these compounds have been detected in space rocks that have fallen to Earth, while others have only been discovered during recent experiments.

“It’s amazing how rich this sample is,” said Professor Russell. “It contains minerals we’ve never seen before in meteorites, as well as an unprecedented mix of materials. It was a very exciting experience studying it.”

This latest study adds to the growing evidence that asteroids brought water and organic matter to Earth.

“The early solar system was a very turbulent place, with millions of asteroids like Bennu roaming around us,” said Dr Ashley King, of the Natural History Museum.

The idea is that these asteroids collided with early Earth, bringing the ingredients that helped form the oceans and make life possible.

But Earth wasn't the only planet to be hit by space rocks, asteroids were also capable of colliding with other planets.

“Earth is unique because it’s the only place we’ve discovered life so far, but we know that asteroids were transporting those ingredients, like carbon and water, across the solar system,” Dr. King noted.

"One of the main questions we're looking at now is whether the conditions were right, why did life appear on Earth, and can we find it elsewhere in our solar system?" King added.

This is a major question that scientists will continue to try to answer.

They may still have decades of research to do with the dust they brought back from Bennu, as well as parts of our own cosmic ocean to explore.

Source: BBC Arabic