London- (BBC):
Could our understanding of the ocean’s depths help solve the mysteries of outer space? NASA’s space mission is leading us to the unexplored depths of our planet.
Oceans cover more than 70 percent of the Earth’s surface, but more than 80 percent of it remains unexplored. In fact, it is often said that we know more about the surface of Mars and the Moon than we do about the ocean floor on our planet!
But NASA is on a mission to change that, as the US space agency explores the depths of the oceans to look for clues to what oceans might look like on other planets, pushing the boundaries of science and technology in one of the harshest environments on our planet. It is a mission full of dangers and wonders, and the danger of an implosion that should not be underestimated at all due to the tremendous pressure in these abyssal depths.
There is hope that the underwater discoveries will help solve some of the mysteries of outer space, while also testing some of the equipment and experiments needed for missions elsewhere in the solar system.
The depths of Earth’s oceans are surprisingly similar to some of the conditions NASA expects to find on other worlds in our solar system. And oceans can even provide clues about where scientists should look for life on other planets.
The deepest part of Earth’s oceans is known as the “Hadal Zone”, which is named after Hades, the Greek god of the underworld, and it is a forbidden place that really deserves that name.
The “Hadal Zone” consists of deep trenches and basins, and extends 11 kilometers (6.8 miles) below the surface of the world’s oceans. Cumulatively, it represents an area of the sea floor the size of Australia. However, only a few vehicles could survive sinking into this dark abyss.
Here, NASA scientists, in partnership with the Woods Hole Oceanographic Institution in Massachusetts, are trying to explore the limits of life on Earth. Even the language that scientists use on their expeditions to this region shares a lot of the terminology used in the space exploration process – marine biologists in recent years have sent several “landers” equipped with sensors and cameras to land on the Hadal floor and take some measurements.
But engineers from NASA’s Jet Propulsion Laboratory in Southern California are building a new, autonomous underwater vehicle called “Orpheus,” after the ancient Greek hero who traveled to the underworld and back, to map the inaccessible depths.
Using visual navigation technology similar to the Perseverance Mars rover, Orpheus uses highly sensitive cameras to identify rock formations, shells and other objects on the ocean floor to create 3-D dotted maps of some clearly distinguishable features (or perhaps the sea floor).
This allows the robot to find its way around and learn where it has already been, but it must also help it shed new light on the biodiversity of this harsh environment. “If Orpheus succeeds, there’s nowhere in the oceans you can’t go,” says Tim Shank, a deep-sea biologist who leads the WHO’s Hadal Zone Exploration Program.
And this wasn’t the first time Shank had tried to reach the dark depths of the Hadal Zone. In 2014, Orpheus’ predecessor, called Nereus, was sent to the Kermadec Trench, which is located northeast of New Zealand. The craft exploded underwater at a depth of 10 kilometers (6.2 miles), likely due to the enormous pressure.
“After 12 hours, we saw them come up in bits,” Shank says, adding that the loss of Nereus made them rethink how they explored the deep sea.
The Orpheus, which is about the size of a quad bike and weighs about 550 pounds (250 kg), is designed to be lighter, smaller and much cheaper than previous underwater vehicles. This would also make it more agile, allowing it to reach previously unexplored trenches and vents on the sea floor.
For a long time, marine biologists thought life in the Hadal region was impossible, but when deep-sea submarines began venturing into the area in the first half of the 20th century, it became clear that some marine creatures could live there.
But it was still believed that all living things live through a food chain that is ultimately fueled by photosynthesis. Plants, algae and some marine bacteria found in surface waters convert the sun’s energy into sugars that they store in their organic matter, which are eaten by herbivores, which in turn are eaten by carnivores.
Scientists were convinced that living organisms on the ocean floor escaped from dead organic matter – animal carcasses, excrement and the constant fall of other organic debris or “marine snow” drifting from above. But it was thought that there wasn’t enough food to keep anything in the way of the marine creatures, and it was thought that the deepest areas would remain extremely dark and cold for life.
But this perception of the ocean depths changed in 1977, when a US research team dropped a remotely operated vehicle as deep as 8,000 feet (2,440 meters) into the Pacific Ocean. The spacecraft was seeking to capture images of hydrothermal vents, where heat from volcanic activity seeps from the ocean floor.
Scientists have discovered vibrant ecosystems around these vents, teeming with marine creatures, such as transparent snails and amphipods, and small, flea-like crustaceans, which have never been seen before.
“With this discovery, we’ve found a completely new way to live on land,” says Shank. “These are animals that don’t need direct sunlight, they live on chemicals from the sea floor.”
Scientists were puzzled: How could these species in the Hadal region withstand such enormous pressure?
“The pressure is up to 15,000 pounds per square inch,” Shank says. “It’s so intense that it squeezes and explodes individual cells of the animal.”
Since seeing it for the first time in 1977, scientists have discovered that organisms that live at such depths have adapted at the cellular level to survive there, Shank says.
Organisms in the hadal zone, such as giant bipedal crustaceans and snailfish, contain enzymes called pizolites (from the Greek pisin meaning pressure), enzymes that prevent cell membranes and proteins from collapsing under extremely high pressure.
Bezolite enzymes resist stress by increasing the space occupied by proteins within an organism’s cells to resist the weight of the surrounding water. “It’s like putting stakes in a tent,” Shank says.
Alvin was the first remotely operated vehicle to explore hydrothermal events when it sank to the deep sea floor in 1977.
The discovery that organisms can not only survive but thrive in such a harsh environment raises important questions for biologists looking beyond the worlds of our own planet – perhaps also found in other ocean worlds.
Beneath the icy surface of Jupiter’s moon Europa, there is an ocean of salt water that is believed to be 40 to 100 miles (60 to 150 kilometers) deep and contain twice as much water as all of Earth’s oceans combined. Nor does sunlight penetrate beneath the thick ice sheet of the moon, “Europe”, in which cracks and fractures intersect. Under the ice crust, the pressure is similar to that of the Hadal region.
“We have Europa here on Earth,” Shank says. “I didn’t understand how we could do exploration on Europa, until we did it on Earth.”
A robot capable of exploring Earth’s Hadal region could do the same on a frozen moon 628.3 million kilometers (390.4 million miles) away.
“The ocean floor is a great test for us to develop the technology we need for a successful mission in one of these ocean worlds,” says Russell Smith, an engineer with NASA’s Jet Propulsion Laboratory who was part of the team that built Orpheus.
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