The origin of life on Earth: an asteroid sample may hold the answer

2023-11-29 10:12:42
This article was originally published in English

Is the key to life on Earth contained in these few grains of black asteroid dust? Scientists at the Natural History Museum in London hope to find the answer.

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Some dust is going on display at the Natural History Museum in London. Wait, don’t leave, it’s not just any speck of dust.

This is an asteroid sample that contains clues to both the origins of life on Earth and the possibility of ending it. Do I have your attention?

Benu is an asteroid near Earth which also orbits the Sun. It travels at a distance of about 120 million kilometers from us, but that hasn’t stopped a NASA space mission from trying to make contact.

After a journey of more than seven years, the OSIRIS-REx mission was able to take a sample from Benu and return to Earth, landing in Utah in the United States. Scientists believe the sample from the asteroid could be a “intact time capsule from the beginning of the solar system” and could help us understand how the Earth was formed and the origins of life.

101955 Bennu – his full name – was named after the mythological bird of ancient Egypt, associated with the Sun god Ra, creation and rebirth. The Egyptian Benu is often considered a source of inspiration for the myth of the phoenix.

Benu is believed to have formed during the creation of the Milky Way 4.56 billion years ago. When the Sun formed, a chain reaction was triggered, generating numerous molecules and chemical substances and creating disks that orbited in a ring around the Sun.

In these protoplanetary disks, materials such as water and iron formed into larger masses, and eventually came together to create planets. Scientists believe that Benu could be an example of one of the first masses created by this phenomenon, before the formation of the planets in our solar system.

The excitement surrounding the study of this potential building block of Earth is palpable in comments from Dr Ashley King, a meteorite researcher at the Natural History Museum Britain. “It’s a bit like an original brick of our solar system.“, he explains.

When we think about the formation of planet Earth, all the ingredients are also contained in Benu. We therefore want to unravel the history of Bénou and learn more about the origin of the solar system and the history of the Earth“, poursuit Ashley King.

Usually, scientists can only study meteorites, that is, asteroids that fall to Earth. However, the latter are irremediably modified by their contact with the earth’s atmosphere. The ability to study an asteroid sampled in space means conditions are more pristine and allow better conclusions to be drawn.

We think this sample comes from the type of asteroid that could be the source of water’s arrival on Earth“, explains Helena Bates, researcher at the Natural History Museum. She continues: “When the Earth formed, the environment was quite dry and we believe that water was brought in from an extraterrestrial source at some point during Earth’s later evolution. We think Benu could be representative of the type of asteroid that brought water to Earth“.

But it’s not just water they’re looking for. The hunt is also on for organic compounds – carbon-containing molecules – that could be the origin of life on Earth.

But if Bénou is generous, he remains no less dangerous. The asteroid is one of the most closely monitored in the entire solar system.

Benu is in an orbit around the Sun quite similar to that of Earth. This means that many times, scientists predicted that it could come into contact with our planet.

The best current estimates of a potential impact are for a direct collision between 2175 and 2300, with a probability of 0.037%.

It is therefore not a very likely event. But if it happened, the results would be devastating. The collision would produce the equivalent of more than 1,200 megatons of TNT, more than 20 times the power of the Tsar Bomba, the most powerful nuclear weapon ever tested.

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