Saturn’s moon Enceladus has conditions that could support microbial life

Scientists didn’t know why Enceladus was the brightest world in the solar system, or how it related to Saturn’s E ring. Cassini found that both the fresh coating on its surface, and icy material in the E ring originate from vents connected to a global subsurface saltwater ocean that might host hydrothermal vents. Image & Caption Credit: NASA / JPL-Caltech

Complex organic molecules have been discovered in the plumes of Saturn’s moon Enceladus. The data transmitted back to Earth by the Cassini Saturn orbiter, which ended its service above the ringed world on Sept. 16, 2017.

Located in the moon’s south polar region, the plumes are made up of ice-covered materials that contain complex organic compounds. Hydrothermal vents beneath the moon’s surface mix up materials from its core, Enceladus’ subsurface ocean and transport the solution upward in the forms of vapor and ice grains.

Smaller, simpler organic compounds were already detected in the plumes years ago by Cassini. However, this is the first time complex organic molecules, which are made up of hundreds of atoms, have been found on Enceladus. These molecules are rarely seen beyond Earth.

The presence of liquid water, hydrothermal vents, and complex organic molecules make the moon’s subsurface ocean potentially habitable for life.

Hydrothermal activity in Enceladus’ core and the rise of organic-rich bubbles. Image Credit: ESA; F. Postberg et al (2018)

Bubbles of gas rising up within the ocean could be transporting these complex molecules from the moon’s porous core to the ocean’s surface just beneath its icy shell. Through cracks in the vents, these bubbles scatter the organic material, some of which is released into space.

Complex organic molecules are produced by both biological and complex chemical processes and can also transported by meteorites, so their discovery is not proof that Enceladus harbors life.

Frank Postberg and Nozair Khawaja of the University of Heidelberg in Germany, who led the study of Cassini‘s data and confirmed the presence of the complex organic molecules, continue to study the composition of the ice and heavy molecules found in Enceladus’s plumes.

“In my opinion, the fragments we found are of hydrothermal origin; in the high pressures and warm temperatures we expect there, it is possible that complex organic molecules can arise,” Postberg said.

A similar process occurs on Earth, where hydrothermal vents at the bottom of the oceans generate complex organic molecules. Microbial life has been found in some of these vents on Earth, which may have played a role in the start of life on our planet.

A paper on the study has been published in the journal Nature.

“Continuing studies of Cassini data will help us unravel the mysteries of this intriguing ocean world,” said Cassini Project Scientist Linda Spilker of NASA’s Jet Propulsion Laboratory via an agency-issued release.

Cassini, a collaborative project between NASA, the European Space Agency and the Italian Space Agency (ASI). Launched on October 15,1997 atop a Titan IVB/Centaur rocket, the mission had spent almost twenty years (19 years and 335 days) in space. The spacecraft spent some 13 years orbiting Saturn and its moons and deployed a lander, Huygens, the only current vehicle to be placed on a world in the outer solar system.

Cassini in orbit above the gas giant Saturn. Image Credit: NASA / JPL-Caltech

Tagged: Cassini Enceladus ESA Lead Stories NASA organics Saturn subsurface ocean

Laurel Kornfeld

Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.