A surprise arctic vent could help in the search for life

New research shows that far away on Earth, submarine activity is similar to Saturn’s icy moon Enceladus. The finding offers a new possibility that could help scientists prepare for future space missions that will investigate the possibility of life on worlds with subsurface oceans.

An international team of researchers discovered a hydrothermal vent called Aurora in the Arctic in 2014 and revisited it in 2019. Closed about 2.5 miles (4 kilometers) under a permanent ice sheet, Aurora is one of the deepest hydrothermal fields on Earth. Earth. So it’s no surprise that researchers have found it to be a natural, pristine laboratory for studying the geology of the area and its ability to host hydrothermal vents over long periods of time – an important aspect for the origin of life in the ice-covered ocean depths. .

“The biggest part of what we may have discovered is a vent beneath the ice-covered ocean, which is also a great place to study organic synthesis, which is relevant to the origin of life and the search for life beyond Earth,” said Chris Herman, a senior scientist at the Woods Hole Oceanographic Institution and lead author of the paper, said in statement.

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Aurora is a seamount that sits atop the Gakkel Ridge, which forms the boundary of a diverging tectonic plate. This ridge, between Greenland and Siberia, spreads very slowly half an inch (centimeter) per year.

As the plates expand, seawater seeps through the cracks Earth’s crust, where the underlying hot magma heats it to temperatures of up to 750 degrees Fahrenheit (400 degrees Celsius). The heat triggers chemical reactions that remove oxygen and other chemicals from the water, which is then released into the ocean as a plume. This process is called hydrothermal ventilation.

Scientists believe that a similar process occurs on some icy moons, especially on Saturn’s moon Enceladus. NASA Cassini The mission, which explored the system from 2004 to 2017, spotted columns of water flowing from the icy crust of the moon’s southern hemisphere.

At Aurora, studying such plumes allows us to understand the composition of the Earth’s crust, the mechanisms that deliver minerals to the seafloor, and how life begins and survives in such extreme conditions. Previous studies have shown that ultra-slow-spreading ridges like Gakkel are not hot enough to support sustained hydrothermal venting. Therefore, scientists thought that it was unlikely to find life in these holes.

“This is a class of vents previously thought to be incapable of supporting the growth of large hydrothermal mineral deposits,” Herman said in a statement. “Until now, scientists assumed that such small volcanic systems could not sustain hydrothermal circulation long enough to grow such large mineral deposits.”

However, the team discovered that Aurora’s hydrothermal field contains high levels of gold, copper and methane. This last chemical is a particularly exciting find because it was discovered by Cassini methane in the plume from Enceladus, potentially hinting at similar deep-sea hydrothermal vents.

At Aurora, Herman’s team used high-resolution sonar and downward-facing cameras to capture images and live video from the vent’s location. Among other features, scientists noticed formations called stalagmite-like hydrothermal vents rising into the water in Aurora. Pale “dots” at the tips of some of them indicate microbial life—the kind of life that might have existed deep in Enceladus’ ocean.

To better understand the subsurface processes in Aurora, the team also collected valuable data about the plume itself. Those results showed that the plume matched those found at other vents located on slow-spreading ridges rich in what geologists call ultramafic rocks, according to the researchers. Ultra basic breeds form are located in the Earth’s mantle in composition, they are close to meteorites.

Similar to the Aurora Field in the Arctic, seafloor vents on Enceladus are also found in the ultra-basic rocksand scientists believe that the vents may play an important role in leaching minerals from the moon’s core into its subsurface ocean — minerals that are critical to life.

Life around hydrothermal vents

Despite the high temperature, the regions around the hydrothermal springs are considered one of the places where early microbial life materialized on Earth (opens in a new tab). Biologists noticed organisms such as yeti crabs, giant trumpets, and deep-sea mussels around hydrothermal vents in the eastern Pacific Ocean.

How do they survive? Too deep to collect sunlight, these organisms cannot rely on photosynthesis. Instead, they use chemicals that come from hydrothermal vents as their energy source. Through a process called chemosynthesisthey leak hydrogen sulfide, carbon dioxide, and other chemicals released from the vent.

“We continue to be amazed at how diverse and beautiful the seabed is,” Herman said. “Every time we go out and explore, we’re surprised because we’re not just finding more of the same. Rather, we keep finding completely new things that are different from anything we’ve seen before.”

This research adds to a growing list of reasons why ocean worlds like Enceladus are among the most interesting places to look for life beyond Earth.

The study is described in a paper (opens in a new tab) published October 31 in the journal Nature Communications.

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