Follow the twisted limbs of your family tree to the original origins of billions of years, and you will see that we all come from dust rich in organic chemistry.
Just where this organic substance comes from has been a topic of debate for over half a century. Now, researchers have found the first evidence of organic matter essential for life on Earth on the surface of an S-type asteroid.
An international team of researchers recently conducted an in-depth analysis of one of the particles returned in 2010 by the Japanese Space Agency’s (JAXA) original Hayabusa mission of the asteroid Itokawa.
Most of the Earth’s meteorites come from S-type asteroids such as Itokawa, so knowing that it could contain essential ingredients for life on our planet is an important step forward in our understanding of how life-forming conditions can arise. So far, most research on organic matter has focused on carbon-rich (c-class) asteroids.
The team looked at the sample and found that organic matter derived from the asteroid developed over time under extreme conditions – with water and organic matter from other sources.
This is similar to the process that took place on Earth, and helps us to better understand how the earliest forms of terrestrial biochemistry can simply be an extension of the chemistry that takes place in many asteroids.
“These findings are very exciting, as they reveal intricate details of the history of an asteroid and how its evolution is so similar to that of the prebiotic Earth,” said Queenie Chan of the Royal Holloway University of London.
Evolutionary models can take us back about 3.5 billion years to a time when life was little more than competing nucleic acid series.
As you go further, we are forced to consider how elements such as hydrogen, oxygen, nitrogen, and carbon can combine to form incredibly complex molecules that are able to organize themselves into things that act like RNA, proteins, and fatty acids.
While researchers in the 1950s considered the first question of how simpler ingredients could cook an organic soup spontaneously, experiments showed that conditions on the earth’s surface could provide sufficient work.
Our focus nearly seven decades later pointed to the slow and steady chemical processes in the rocks that have joined together in worlds like ours.
Evidence is not difficult to obtain. It is now clear that a steady rain of rock and ice billions of years ago could have produced molecules of cyanide, the sugar ribose and even amino acids – along with a generous donation of water – on earth.
But the extent to which the chemistry of meteorites could have been contaminated by things on earth leaves room for doubt.
Since the return of Hayabusa a decade ago, more than 900 particles of pristine asteroid dirt taken from the payload have been separated and stored in a clean JAXA room.
Less than ten have been studied for signs of organic chemistry, but all have been found to contain molecules consisting mainly of carbon.
Itokawa is referred to as a rocky (or siliceous) class of asteroid, or s-class. After early studies on the material, it is also believed to be an ordinary chondrite – a relatively unmodified type of space rock that represents a more primitive state of the inner Solar System.
Since these types of asteroids form a large part of the mineral form that breaks down on our planet, they usually do not contain much of the organic chemistry, the early findings are, to say the least, interesting.
Chan and her colleagues took just one of these dust grains, a particle 30 micrometers wide, that formed just like the continent of South America, and did a detailed analysis of the composition, including a study of the water content.
They found a rich variety of carbonaceous compounds, including signs of disordered polyaromatic molecules of a clearly extraterrestrial origin and graphite structures.
“After studying an international team of researchers in detail, we kept a single-grain analysis, nicknamed ‘Amazon’, of primitive (unheated) and processed (heated) organic matter within ten microns (one thousandth of a centimeter). from a distance, ”says Chan.
“The organic material that has been heated indicates that the asteroid has been heated to more than 600 ° C in the past. The presence of unheated organic material, very close to it, means that the fall of primitive organic materials came to the surface of Itokawa. after the asteroid has cooled. ‘
Itokawa has an exciting history for a rock that has nothing better to do than idle a few billion years around the sun, after it has been adapted with a good baking, dehydrated and then again with a new layer fresh material is hydrated.
Although the story is not as exciting as the history of our planet, the asteroid describes the cooking of organic matter in space as a complicated process and is not limited to carbon-rich asteroids.
Late last year, Hayabusa2 returned with a sample of a C-Class asteroid near Earth called Ryugu. If you compare the contents of its payload with that of its predecessor, it will undoubtedly carry even more knowledge about how organic chemistry develops in space.
The question of the origin of life and its apparent uniqueness on earth is what we will be looking for answers to for a long time to come. But each new discovery points to a story that extends far beyond the safe, warm puddle of our newborn planet.
This research was published in Scientific reports.