Saturday, July 13, 2024

Low Gravity On Ocean Worlds Might Help Sustain Warm Water Circulation For Millions Of Years


A new study used a complex computer model to investigate how the influence of low gravity, as found on ocean worlds in our outer solar system, could influence flows of water and heat below their seafloors.

The work was conducted as part of a multi-institutional “Exploring Ocean WorldsNASA program, led by Woods Hole Oceanographic Institute (WHOI) Senior Scientist Chris German. It has shed new light on the potential for seafloor hydrothermal venting — which hosts some of the most primitive life forms on Earth — to occur on other “Ocean World” moons orbiting giant planets in the outer Solar System.

Our solar system contains many “ocean worlds,” planets and moons that currently have, or have had in the past, a liquid ocean. Some of these ocean worlds may release enough heat internally to drive hydrothermal circulation – water that flows into the seafloor, circulates and is warmed, and flows back out.

On Earth, these flows can carry heat and chemicals, some of which are key to supporting lush seafloor ecosystems. These rock-heat-fluid systems were discovered on Earth’s seafloor in the 1970s, and many scientists think they may exist elsewhere in our solar system – this is a topic of great interest, especially because there is potential to support life.

A research team at University of California Santa Cruz, in collaboration with colleagues at the Blue Marble Space Institute of Science, WHOI and Nantes Université have published their new study in the Journal of Geophysical Research: Planets, showing how hydrothermal systems like those seen on Earth might differ under lower gravity conditions of other ocean worlds.

Many people have heard about high-temperature vents on Earth’s seafloor, sometimes called “black smokers,” where fluids heated above 300°C/572°F (much hotter than the boiling point of water at sea level on Earth) jet into the ocean, depositing metal ores and helping to support exotic life. While these high-temperature systems are driven mainly by subseafloor volcanic activity, a much larger volume of fluid flows in and out of Earth’s seafloor at lower temperatures, driven mainly by “background” cooling of the planet.

According to Andrew Fisher, study lead author and a distinguished professor of earth and planetary sciences at UC Santa Cruz:

“The flow of water through low-temperature venting is equivalent, in terms of the amount of water being discharged, to all of the rivers and streams on Earth, and is responsible for about a quarter of Earth’s heat loss. The entire volume of the ocean is pumped in and out of the seafloor about every half-million years.”

While Donna Blackman, an EPS researcher at UC Santa Cruz and third author on the new paper, added:

“Many previous studies of hydrothermal circulation on Europa and Enceladus (moons of Jupiter and Saturn) have considered higher temperature fluids, and cartoons and other drawings often illustrate systems on their seafloors that look like black smokers on Earth. Lower temperature flows are at least as likely to occur, if not more likely.”

Check out the study here.

John Liang
John Liang
John Liang is the News Editor at He first got the diving bug while in High School in Cairo, Egypt, where he earned his PADI Open Water Diver certification in the Red Sea off the Sinai Peninsula. Since then, John has dived in a volcanic lake in Guatemala, among white-tipped sharks off the Pacific Coast of Costa Rica, and other places including a pool in Las Vegas helping to break the world record for the largest underwater press conference.