Science & Technology

An Icy Moon of Saturn Is Spewing Life-Friendly Organic Molecules

Here's some huge news: It turns out that Enceladus, a famous icy moon of Saturn that has dozens of geysers erupting from its surface, also has complex organic molecules. But there are some things you should know before you go yelling "extraterrestrial life!" Organic molecules, or "organics" — which include elements such as carbon — can sometimes indicate life processes, but not always.

Life on Ice

Organic molecules, compounds that contain atoms of carbon, are the building blocks of life — think carbohydrates, proteins, lipids, and nucleic acids. Although all life contains organic molecules, not all organic molecules are signs of life. Still, scientists say the new organics find is the most compelling evidence yet that Enceladus could host microbial life. That's pretty extraordinary, given that the moon is, on average, about 10 times further away from the sun than Earth is. That means any life on this moon would need to receive heat from another source — perhaps Saturn — to survive.

"We are, yet again, blown away by Enceladus," said study co-author Christopher Glein, a space scientist with the Southwest Research Institute who studies oceans in distant worlds. "With complex organic molecules emanating from its liquid water ocean," Glein added in a statement, "this moon is the only body besides Earth known to simultaneously satisfy all of the basic requirements for life as we know it."

The new study, which was published in Nature, isn't the first organic find on Enceladus. Researchers previously found some simple organic molecules containing only a few carbon atoms, but this discovery shows the most complex organics by far. The newly found molecules have masses above 200 atomic mass units, which is about 10 times heavier than methane.

Scientists made the discovery using data from the Cassini spacecraft, which found the organics in a plume from Enceladus' subsurface. As the spacecraft ran out of fuel last September, NASA deliberately threw it into Saturn on a suicide plunge. That was to avoid any chance of Cassini crashing into Enceladus, or any other icy moon for that matter, and contaminating the surface with microbes from Earth. The new discovery from this fallen vessel goes to show you that even when spacecraft die, their data lives on.

Mars, Mercury, and Beyond

And speaking of life, scientists just found another location in the solar system that has organic molecules. Earlier this month, NASA announced its Curiosity rover on Mars found organics at two different drill sites.

It's too early to say if the Martian organics are from life or not, but the team said they were impressed that the Red Planet's radiation and wind didn't destroy the organics over millions of years. "We're in a really good position to move forward looking for signs of life," said study leader Jennifer Eigenbrode, a biogeochemist at NASA's Goddard Space Flight Center in Maryland, in an interview in Science.

But it's good to remember that organics pop up all over the solar system — even in places that are unlikely to host life. Some examples include the hot planet Mercury, which is tiny and too close to the sun for life, or some comets, which are small bodies made up of ice and dust.

So how did life on Earth begin? Is there life elsewhere? We're still learning the answer to those questions, but the pieces of the puzzle are scattered all over the solar system. All we have to do is put them together.

Looking for life in all the wrong places? Check out "Aliens: The World's Leading Scientists on the Search for Extraterrestrial Life" by Jim Al-Khalili. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Ingredients For Life? Saturn Moon Enceladus Is Spewing Complex Organic Materials

Written by Elizabeth Howell June 29, 2018

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