“The Death of Mars” –Pluto-Size Asteroid Ignited Ancient Climate Change

Ancient Mars Ocean

 

In the mid-1980s, a group of American archaeologists pored over satellite images trying to understand what had become of the Mayan civilization that had once ruled over Mexico’s Yucatan Peninsula, discovered a pattern: a near-perfect ring of sinkholes -cenotes- about 200km across,, encircling the Yucatecan capital, Merida, and port towns of Sisal and Progreso. A pattern created by an ancient asteroid explosion that may yield clues to the lost ocean and atmosphere of Mars.

When the researchers presented their findings to fellow satellite specialists at a scientific conference in Acapulco, Mexico, in 1988, one scientist in the audience, Adriana Ocampo, then a young planetary geologist at NASA, the circular formation saw not just a huge ring, she saw but a bullseye –the impact crater of an asteroid that hit with the force of 10 billion Hiroshima nuclear bombs that scarred the planet in ways still being revealed 66 million years on. Today, the center of the bullseye is a buried a kilometer below a tiny town called Chicxulub Puerto.

“As soon as I saw the slides that was my ‘Aha!’ moment. ‘This is something amazing,.‘This could be it’,” Ocampo, now director of NASA’s Lucy mission, which will send a spacecraft into Jupiter’s orbit in 2021 told the BBC. “I was really excited inside but I kept cool because obviously you don’t know until you have more evidence. They didn’t even know what I was talking about!” she laughed, three decades later.

The key to her ‘Aha! moment’ had been an intuition she’d picked up after working with a legendary figure in space science, Eugene Shoemaker, the pioneering American geologist who as one of the founders of the field of planetary science and remains, 21 years after his death, the only person whose ashes are buried on the Moon – had instructed Ocampo that near perfect circles were unlikely to have been caused by other terrestrial forces, and could provide clues to Earth’s geological development.

Ocampo’s chance encounter was the beginning of a scientific correspondence that would establish the foundations for what most scientists believe today: that this ring corresponds to the edge of the crater caused by an asteroid described by Peter Brannen in The Ends of the World as follows: “The asteroid itself was so large that, even at the moment of impact, the top of it might have still towered more than a mile above the cruising altitude of a 747. In its nearly instantaneous descent, it compressed the air below it so violently that it briefly became several times hotter than the surface of the sun,” hitting Earth with enough force enough to lift a mountain back into space at escape velocity.

“Impact!” The Asteroid That Towered a Mile Above the Cruising Altitude of a 747

In the years that followed the cataclysmic impact, reports the BBC, the Earth would have changed beyond recognition, with the plume of ash blocking the sky and creating perpetual night-time for more than a year, plunging temperatures below freezing, and killing off about 75% of all life on Earth – including almost all the dinosaurs.

The scientists drilled into the Chicxulub crater buried underneath the Yucatán Peninsula recovered rocks from under the Gulf of Mexico that were hit by the asteroid, creating the niche that made the rise of homo sapiens possible. The 15 km-wide asteroid could not have hit a worse place on Earth. “All these fossils occur in a layer no more than 10cm thick,” said palaeontologist Ken Lacovara. “They died suddenly and were buried quickly. It tells us this is a moment in geological time. That’s days, weeks, maybe months. But this is not thousands of years; it’s not hundreds of thousands of years. This is essentially an instantaneous event.”

 

 

Without that impact, humanity might well have never existed. “It gave us a leg up to be able to compete, to be able to flourish, as we eventually did,” she said.

“Lost!” How Mars’ Ancient Ocean Vanished into Space (WATCH Today’s ‘Galaxy’ Stream)

Debris discovered from asteroid impacts on Mars compared with ejecta from the Chicxulub Crater shows similarities that indicate that Mars must once have had much thicker an atmosphere than it does now – one closer to the atmosphere that supports life on Earth. “It’s important for us to know what happened in the past to be prepared for the future,” Ocampo said. “It provides a really good insight into what has happened in the geological evolution of Mars.”

“It’s a natural laboratory because of its similarities to what we can find on other planets like Mars where humans can’t go,” Ocampo said of Mexico’s smaller crater.

Today, Mars is a frigid desert world with a carbon dioxide atmosphere 100 times thinner than Earth’s. But evidence suggests that in the early history of our solar system, Mars’ surface likely hosted an ocean as deep as the Mediterranean Sea. As the planet’s atmosphere thinned, however, most of the ocean was lost to space. The remainder of the water is locked in the Martian ice caps.

Astronomers from UC Santa Cruz, Caltech and MIT proposed that a giant meteorite or comet the size of Pluto, more than 1,200 miles in diameter – sped toward ancient Mars at up to 21,600 miles an hour, crashed at a steep slant into the planet about 3.9 billion years ago, and blasted out the huge elliptical scar measuring 5,300 miles across that now forms all of the planet’s northern lowlands, while leaving the southern highlands relatively undamaged. An impact so big that it has left half the red planet at a lower elevation.

If the theories are right, it blasted out the biggest crater that any planet has ever survived. It was a convulsion far bigger than the one that drove the dinosaurs to extinction on Earth. One region of the surface is the huge oval-shaped scar of the impact itself, covering more than a third of the Martian surface and including all the vast low-lying lands of the planet’s far north where the Phoenix spacecraft is now digging up buried nuggets of ice. The other is the even larger highland region to the south, marked by deep canyons, high mountains and the remains of giant volcanoes.

Mars’ Discovery –Huge Lake of Liquid Water Observed Under South Pole: “We Were Not Seeing the Thing That was Right Under Our Noses”

NASA’s Mars Reconnaissance Orbiter and Mars Global Surveyor have provided detailed information about the elevations and gravity of the Red Planet’s northern and southern hemispheres. The mystery of the two-faced nature of Mars has perplexed scientists since the first comprehensive images of the surface were beamed home by NASA spacecraft in the 1970s. A giant northern basin that covers about 40 percent of Mars’ surface, sometimes called the Borealis basin, is the remains of a colossal impact early in the solar system’s formation, the new analysis suggests. At 8,500 kilometers (5,300 miles) across, it is about four times wider than the next-biggest impact basin known, the Hellas basin on southern Mars.

“Worlds in Collision” –Why Northern Mars Is Lower in Altitude Than Southern Mars

An accompanying report calculated that the impacting object that produced the Borealis basin must have been about 2,000 kilometers (1,200 miles) across. That’s larger than Pluto. It appears to have held an ocean in crater the size of the combined areas of Asia, Europe and Australia, the early days of the planet, before Mars lost so much of its atmosphere and the water either sublimated away or froze beneath the surface.

Information from Chicxulub could also give clues about whether or not there was water on the surface of Mars long after the planet was dented by the massive asteroid hit.

Scientists have detected frozen water on the surface of the red planet. Martian seas could have disappeared when the planet was bombarded by smaller meteors that changed its atmosphere and dried it out, Ocampo said.

The Daily Galaxy via BBC http://www.bbc.com/travel/story/20181111-the-buried-secrets-of-the-deadliest-location-on-earth and https://solarsystem.nasa.gov/people/1780/adriana-ocampo/

error

"The Galaxy" in Your Inbox, Free, Daily