Becky Ferreira
09/17/2021 7:29 PM
Clarín.com
The New York Times International Weekly
Updated 9/17/2021 7:29 PM
The first rock art.
The dawn of agriculture.
While these are some of the most pivotal moments in humanity's early days, our most dramatic origin story begins 66 million years ago.
It was the
apocalyptic moment
when a rock from outer space crashed into Earth, ending the age of dinosaurs and offering a new and abundant world to our mammalian ancestors.
For 40 years, scientists have studied the history of this catastrophic object, now known as the
Chicxulub
impactor
.
An image of the current terrestrial remains of the Chicxulub meteorite in Yucatán, which are 45 cm from the ground.
Today, the impactor represents more than just a bad day on Earth;
on the contrary, it has become a kind of
Rosetta stone
that can unravel deeper enigmas about the origins of life and the future of human civilization, both on our planet and on other worlds in the galaxy.
"The Chicxulub impact completely changed the geological and biological evolution of planet Earth," says David Kring, a planetary geologist who directs the Center for Lunar Science and Exploration in Houston and was part of the team that announced the
discovery of the
impact
crater
of Chicxulub under the Mexican Yucatan peninsula in 1991.
"This is such a great scientific story with popular appeal because it extinguished the dinosaurs and cleared the slate, if you will, for the
evolution of mammals
that led to humans, which is going to captivate both the scientific community and the public. during years".
For decades, scientists argued about the cause of death of dinosaurs.
Volcanic eruptions and other exotic hypotheses were proposed, but the scientific consensus favored a rock from space as the killer.
The Chicxulub theory now reigns so supreme that scientists have reconstructed detailed timelines of what happened on that fateful day, and other researchers are writing what might be called the prequel, looking for the
extraterrestrial origins
of the event to which we partially owe our existence.
As more advanced tools and techniques become available, scientists have been able to extract new and precise insights into this epic annihilation on our planet, and what it may mean for the early days of life itself.
The latest finding comes from a study published in July in the journal
Icarus
that searched for the original home of the Chicxulub impactor.
To do this, it took advantage of the immense processing power of a
NASA
supercomputer
to model the movements of some 130,000 asteroids in the main belt between the orbits of Mars and Jupiter.
"Ultimately, we want to solve big questions, and this kind of work allows us to go after some of them," said Bill Bottke, co-author of the study and director of the department of space studies at the
Southwest Research Institute in Boulder,
Colorado.
The Icarus study is part of a constant stream of dazzling impact ideas on your creativity, often to the point of controversy.
This year, for example, a team from
Harvard University
revived the possibility that the impactor was a comet, sparking rejection from many scientists in the industry.
Another scientist, Lisa Randall of Harvard University, even stepped away to present a
galactic view
of the Chicxulub event.
In his 2015 book
"Dark Matter and Dinosaurs,"
Randall proposes that the Milky Way contains a layer of dark matter, a mysterious hypothetical substance, that may
help push
comets from the outer solar system toward Earth.
Although this explanation has not won many followers, it demonstrates how Chicxulub draws
prismatic perspectives
from the world of cosmology, computer science, astrobiology, and other fields.
Bottke said access to NASA's Pleiades supercomputer was a "game changer" for his team, allowing researchers to
simulate
a huge population of asteroids over hundreds of millions of years.
This Big Data technique helped fit the strong geological evidence that the impactor was a carbonaceous asteroid - and not a comet - with a possible origin in the
outer asteroid belt.
This distant region between Mars and Jupiter contains many carbonaceous asteroids several kilometers wide similar to the Chicxulub impactor.
However, these rocks are not gravitationally hoisted into collision courses with planets as frequently as asteroids in the inner belt region, where there are fewer objects that match the Chicxulub composition.
"We couldn't find an obvious solution to the provenance of one of the biggest shocks to hit Earth in recent times," Bottke said.
"Essentially, a lot of the possibilities that we had tried were not working. It was really
frustrating
and it seemed like we were missing something."
The team's supercomputing approach revealed that Chicxulub-like asteroids
escape
the outer belt
10 times more
frequently
than previous models assumed.
That increases the odds that the rock that killed the dinosaurs may have originated there.
"This is confirmation of a really cool idea, and I think it helps to understand a lot more about how the asteroid belt may be influencing Earth for billions of years," Bottke said.
Sean Gulick, a planetary geophysicist at the University of Texas at Austin, who was one of the leaders of the 2016 scientific drilling expedition that obtained valuable rock cores from the Chicxulub crater, said the paper was an interesting approach to conducting "the Forensic science, if you will, on where the impactor came from. It's intriguing because it was a very important event for the evolution of our planet and ourselves. "
Gulick also noted that the study highlighted the dangers posed by asteroids over time, including the risks our civilization faces on the planet.
The Chicxulub impact and the fate of the dinosaurs are frequently invoked as the definitive argument both for investing in planetary defense research and for expanding our species beyond Earth.
Although it should be noted that other worlds, including Mars, are not exempt from large-scale asteroid impacts.
But Chicxulub also sheds light on some of the most suggestive questions about the appearance of life.
Kring has been fascinated by this topic for a long time, and has helped produce a great deal of research on the
microbial ecosystems
that emerged in the aftermath of the apocalyptic event.
"There is an argument that this type of bombardment is involved not only in disturbing the evolution of life, but is actually involved in the origin of life on our planet," he said.
"Understanding these processes is important, and our best measurements of some of these consequences on Earth are going to come from the youngest of these impactors, like Chicxulub, because the evidence is more robust."
The mission that Gulick helped lead continues to clarify the impact's role as a destroyer and as a crucible of life.
As researchers delved deep into the buried doomsday event, they found dusty traces of the impactor, the
sandy recoil
of the tsunami it had created, and the fossilized remains of organisms that thrived in its aftermath.
Perhaps most surprising is that a study published this summer describes the current microbial descendants of those early adopters of the crater, who still live in the shadow of the catastrophe their ancestors colonized.
"It's amazing to me that you can have an impact and create an
ecosystem
and that 66 million years later, there is still life present there because of this precondition," Gulick said.
"On a larger scale, maybe habitats can be generated with impacts really early in Earth's history and ecosystems can survive later. That reflects one of the ways that life could be kick-started."
In this sense, the Chicxulub impactor actually has galactic implications as a time capsule of both biological disaster and the birth of new life.
Other worlds with life along the Milky Way could be
molded r
s similarly by asteroid impacts with stories of destruction and own recovery.
"This is an issue that potentially goes well beyond the extinction of the dinosaurs," Kring said.
c.2021 The New York Times Company
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