In some ways, we know more about other planets than the depths of our oceans. These uncharted seafloors often host unique ecosystems that can teach us not only about life on Earth — but possibly about life on other celestial bodies.
After recent exploration, researchers report the appearance of five new hydrothermal vents — openings on the seafloor that release heated, mineral-rich water, supporting unique ecosystems in deep ocean environments. And these were found at 2,550 meters (8366 feet, or 1.6 miles) below the surface.
Life as we don’t know it
Most ecosystems on Earth require light and heat to survive. The deeper you go into the ocean, the less you have of both. Water absorbs some of the Sun’s light, and deep underwater, there’s almost complete darkness. But geology has offered life a hand through hydrothermal vents.
Hydrothermal vents are fissures that release geothermally heated water. Found primarily in regions with volcanic activity, these vents form along mid-ocean ridges, where tectonic plates diverge. The water emitted by hydrothermal vents is rich in dissolved minerals and supports highly unique ecosystems, largely independent of sunlight.
These ecosystems are populated by a variety of organisms, including extremophiles that can withstand the incredibly high pressure and temperatures. In fact, some researchers suspect that life on Earth might have emerged around hydrothermal vents. So, whenever researchers spot new hydrothermal vents, it’s always pretty exciting.
The newly discovered vents are located on the East Pacific Rise, a mid-ocean ridge where two tectonic plates are diverging (moving apart from each other) at a speed of around 11 cm (4.2 in) per year. Researchers were inspecting the area using Sentry, an autonomous underwater vehicle (AUV) operated by the Woods Hole Oceanographic Institution (WHOI), and Alvin, a human occupied vehicle also operated by WHOI.
Submersible teamwork
“By jointly operating these two cutting-edge deep-sea submersibles, we are able to make remarkable new discoveries about how seafloor in the deep oceans is constructed, in some of the most inhospitable environments on Earth,” said Ross Parnell-Turner, a co-lead scientist on the expedition from the Scripps Institution of Oceanography and a marine geophysicist specializing in high-resolution seafloor mapping of the volcanic and hydrothermal terrain.
Each night, Sentry would go in and produce high-resolution maps with its sensors. In the morning, based on these maps, Alvin would go and explore the most interesting areas.
“The high-resolution maps from Sentry allow us to spot likely new hydrothermal fields soon after Sentry comes back on deck,” said Jill McDermott, associate professor of Earth and environmental sciences and director of Lehigh Oceans Research Center. McDermott served as chief scientist of the expedition and co-lead scientist specializing in hydrothermal vent geochemistry. “This gives us great targets for Alvin and the opportunity to make multiple discoveries in a single dive.”
All the vents are ejecting hot liquid at temperatures over 300°C (570°F), along with chemicals and minerals important for deep-sea ecosystems. Based on what researchers know about the vents so far, they seem to be producing everything that’s needed for a deep-sea ecosystem.
This type of hydrothermal vent quite possibly exists on other celestial bodies as well. For example, they could exist on Jupiter’s Moon Europa. Here an ice-covered ocean is believed to lie beneath the frozen surface.
The presence of a subsurface ocean, coupled with the moon’s geologic activity, suggests that Europa could have active hydrothermal vents, potentially mirroring Earth’s. These vents might provide the necessary ingredients to support life, making Europa a prime candidate for life beyond Earth.
Vents on Earth and beyond
However, before we start exploring the vents on Europa, we’d do well to investigate those on our planet — and there’s still a lot we don’t know.
“The mid-ocean ridge accounts for more than 75% of all volcanic activity on our planet,” said Thibaut Barreyre, a co-lead scientist on the expedition from CNRS, Univ Brest, France and an expert in thermal measurements and modeling of hydrothermal vents. “It is dotted with thousands of deep-sea hot springs like these, which all together extract 10% of the Earth’s total internal heat. We want to increase our understanding of how hydrothermal vents release heat and chemicals as they flow through the seafloor and affect the global ocean.”
Scientists plan to continue studying hydrothermal activity in follow-up expeditions in a quest to better understand the chemical and biological processes that shape deep-life ocean. If we can understand the vents here, we can better prepare a mission to search for alien life on Europa.
Notably, NASA’s upcoming Europa Clipper mission is set to launch in the 2020s, designed to investigate Europa’s ice shell, underlying ocean, and geologic composition. Equipped with a suite of scientific instruments, the Europa Clipper aims to determine the habitability of Europa’s ocean and to search for signs of possible life in the subsurface water.
By closely studying the moon’s surface and possibly sampling the water vapor plumes believed to emanate from its ocean, the mission could provide critical data on the existence and nature of hydrothermal vents beyond Earth. This exploration is pivotal, as understanding Europa’s hydrothermal vents may hold the key to discovering life in environments once thought to be inhospitable — including extraterrestrial life.
