When scientists find microbial life to thrive in some of the most extreme environments on Earth, it gives them hope that they can find life on other planets.
Now, researchers have discovered billions of bacteria living in tiny cracks in volcanic rocks below the ocean floor, more than nine miles below the ocean surface and an additional 300 feet below the ocean floor. ocean, according to a new study released Thursday.
And they believe that similar tiny cracks filled with clay in rocks on or below Mars could be a similar center of life.
The upper ocean crust, known as the ocean floor, was continuously created on Earth for about 3.8 billion years. Underwater volcanoes release lava at 2200 degrees Fahrenheit, which solidifies into basalt rock when hot rock reacts to the depths of the cold ocean.
Hydrothermal vents along the ocean floor are known to support bacteria and other life forms that convert minerals into energy rather than light.
Previously, researchers studied bacteria systems that were between 3.5 and 8 million years old. But 90% of the bottom of the ocean is much older than that.
Yohey Suzuki, associate professor in the Department of Earth and Planetary Sciences at the University of Tokyo, and his colleagues studied samples of basaltic lava found 328 feet below the ocean floor between Tahiti and New Zealand which ranged from 33 million to 104 million years ago.
There they found a wealth of single-cell microbial life living in tiny cracks among the rock, which were rich in iron and clay. To be exact, they estimate that 10 billion bacterial cells live per cubic centimeter in these communities. (Bacteria known to live in mud along the seabed turn pale, by comparison, at 100 cells per cubic centimeter.)
Researchers believe that the iron content of clay found deep below the ocean floor promotes the growth of these large bacterial communities. The study published in the journal Communications Biology.
“I thought it was a dream to see a microbial life so rich in rocks,” said Suzuki. “I almost now expect to be able to find life on Mars. If not, it must be that life depends on another process that Mars does not have, like plate tectonics. “
From the bottom of the ocean to Mars
Cracks form when the lava cools, creating narrow spaces less than a millimeter in diameter. Millions of years of residue and accumulation fill them with mineral-infused clay. Then the bacteria find a nice home there and settle there.
“These cracks are a very friendly place for life. Clay minerals are like magic material on Earth; if you can find clay minerals, you can almost always find microbes that live there, ”said Suzuki.
The bacteria that Suzuki and her colleagues found are similar to the way our cells produce energy, a process that relies on organic nutrients for oxygen. Instead of human resources get from the surface of the Earth, they get what they need from the clay minerals.
Clay is something that NASA’s Curiosity rover has explored a lot on Mars.
Since Curiosity landed in 2012, it has explored the Gale crater, a vast, dry ancient lakebed with a 16,404-foot mountain – Mount Sharp – at its center.
Streams and lakes probably filled the Gale crater billions of years ago, which is why NASA landed the rover there in 2012. Scientists want to know if ancient Mars once supported microbial life .
Mars, like Earth, also has a basaltic crust that formed four billion years ago. And in recent years, groundwater and methane have been detected on the red planet.
Curiosity observed and drilled samples of rocks rich in clay from the lake bed.
The clay minerals present in these rocks on the Martian surface could be similar to those of oceanic rock cracks.
“Minerals are like a fingerprint of the conditions that were present when clay was formed. Neutral to slightly alkaline levels, low temperature, moderate salinity, iron-rich environment, basalt rock – all of these conditions are shared between the deep ocean and the surface of Mars, “said Suzuki.
His team is working with researchers at NASA’s Johnson Space Center in Houston, Texas to develop a plan to examine and analyze rock samples that will return one day from March.
A 3D x-ray could help them take a look inside the samples and look for cracks filled with minerals – and perhaps find evidence of life.
“This discovery of life where no one expected it in a solid rock under the seabed could be a game-changer for the search for life in space,” said Suzuki.
Study the bottom of the ocean
But the quest for bacteria deep under the ocean floor is tricky.
“Honestly, it was a very unexpected discovery. I was very lucky because I almost gave up, “said Suzuki.
The samples were taken in 2010 during the Integrated Ocean Drilling Program, an international marine research program, which led researchers from Tahiti to New Zealand. He stopped at three places along the way, using a 9.7-mile-long metal tube to reach the bottom of the ocean and then drill 410 feet below. Carrots, sediment and solid rocks have been recovered.
The samples were taken away from the hydrothermal vents to avoid contamination, in case the bacteria were transported from one of them to the rocks, and the rocks were sterilized during their ascent.
Tearing and crushing the rock did not work.
Suzuki, inspired by the thin slices of tissue samples that pathologists use to diagnose illnesses, coated the rocks with epoxy to maintain the shape of the rock, then cut thin layers. He washed the thin pieces with a dye that would stain any DNA present.
Under his microscope, he saw green bacterial cells, surrounded by orange clay and black rock. Suzuki was able to perform DNA analysis of the entire genome and identify what was inside the cracks.
He found evidence of life.