Rare space rock holds secret to life on Earth

Time capsule: Minerals and molecules in Aguas Zarcas were forged billions of years ago. © Laurence Garvie

Do meteorites contain the building blocks for life? Scientists have found organic molecules in a 4.5 billion-year-old meteorite, raising the possibility that life came from outer space.

One night last year, a thunderclap made people look outside in Aguas Zarcas, Costa Rica. A blaze of orange and green light streaked across the sky. Dogs barked and children stared as fireballs the size of grapefruit fell on the village, punching holes in roofs and shaking houses.

Tens of thousands of meteorites plunge through the Earth’s atmosphere every year, though humans rarely get to witness their spectacular descent. But Aguas Zarcas (as the rocks became collectively named) was no ordinary meteorite. It was a rare carbonaceous chondrite – older than the Sun, more valuable than gold, and almost alive.

Most meteorites are made of rock and metal, but Aguas Zarcas contains amino acids, the building blocks for all life on Earth. A similar meteorite that landed in 1969 in Murchison, Australia, had 100 different types of amino acid.

This discovery is a unique opportunity. Organic compounds are extremely delicate and easily destroyed when exposed to moisture. Preserved in space for billions of years, they can be lost in seconds. Scientists believe this happened with Murchison, but they hope the 30kg of space rock rescued from Aguas Zarcas will provide a glimpse into the past.

Within these rocks are eight billion years of galactic history, including particles of diamond and graphite from dying stars older than our own solar system. Researchers hope these pristine time capsules will shed more light on the origins of the Universe.

So, do meteorites contain the building blocks for life?

We are stardust

Yes. All the basic ingredients for life are inside meteorites and we know that millions of these rocks have collided with the Earth. So, it is far more likely that life came from space than developed independently on our planet.

No. It needs liquid water and an atmosphere to flourish. The radiation in deep space would kill it. The evolution of life depends on Earth’s climate and environment.

You Decide

  1. Is there life on other planets?

Activities

  1. Draw a diagram of our solar system and include the asteroid belt between Mars and Jupiter.

Some People Say...

“It really is the most poetic thing I know about physics: you are all stardust.”

Lawrence M Krauss, American-Canadian theoretical physicist and cosmologist

What do you think?

Q & A

What do we know?
Life needs six chemical elements (oxygen, hydrogen, carbon, nitrogen, sulphur, and phosphorus), liquid water and an energy source to power organic processes. These chemicals form into increasingly more complex molecules, from amino acids to proteins, sugars and, finally, organic life itself.
What do we not know?
Whether these building blocks in meteorites could form microorganisms. Sceptics say we have only found small amounts of these molecules and, in the absence of liquid water, the chemical reactions involved would be very difficult or impossible. However, others point to evidence of higher concentrations of organic molecules in comets.

Word Watch

Aguas Zarcas
Meteorites are named after the place where they land. The size of a washing-machine, Aguas Zarcas broke up above Costa Rica on 23 April 2019. It joined over 60,000 meteorites that have been found and classified by scientists.
Meteorites
Space rocks that fall to Earth are called meteorites and should not be confused with meteors, which burn up in the planet’s atmosphere as “shooting stars”. In space, they are known as meteoroids and are fragments of much larger asteroids and comets.
Descent
Moving downwards, dropping, or falling.
Collectively
As a group; as a whole.
Carbonaceous chondrite
These rocks resemble lumps of coal, with a sparkling crust that forms as they enter the Earth’s atmosphere. They have a strong earthy smell that some compare to compost, diesel, cooking gas, or Brussels sprouts.
More valuable than gold
The Aguas Zarcas attracted meteorite hunters from all over the world, offering as much as $400 (£305) per gram.
Rescued
By a stroke of luck, the meteorite landed five days before the start of the Costa Rican rainy season. Had it arrived later, the precious organic information would have been lost.
Pristine
In its original condition; unspoilt.
Time capsules
Containing something that represents its time to be discovered in the future.

PDF Download

Please click on "Print view" at the top of the page to see a print friendly version of the article.