Could there be life in Pluto's ocean?

Could there be life in Pluto’s ocean?
View of Pluto with color-coded topography as measured by NASA's New Horizons spacecraft. Purple and blue are low and yellow and red are high, and the informally named Sputnik Planitia stands out at top as a broad, 1300 km- (800 mile-) wide, 2.5 km- (1.5 mile-) deep elliptical basin, most likely the site of an ancient impact on Pluto. New Horizons data imply that deep beneath this nitrogen-ice filled basin is an ocean of dense, salty, ammonia-rich water. Credit: P.M. Schenk LPI/JHUAPL/SwRI/NASA

Pluto is thought to possess a subsurface ocean, which is not so much a sign of water as it is a tremendous clue that other dwarf planets in deep space also may contain similarly exotic oceans, naturally leading to the question of life, said one co-investigator with NASA's New Horizon mission to Pluto and the Kuiper Belt.

William McKinnon, professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis and a co-author on two of four new Pluto studies published Dec. 1 in Nature, argues that beneath the heart-shaped region on Pluto known as Sputnik Planitia there lies an ocean laden with ammonia.

The presence of the pungent, colorless liquid helps to explain not only Pluto's orientation in space but also the persistence of the massive, ice-capped ocean that other researchers call "slushy"—but McKinnon prefers to depict as syrupy.

Using computer models along with topographical and compositional data culled from the New Horizon spacecraft's July 2015 flyby of Pluto, McKinnon led a study on Sputnik Planitia's churning nitrogen ice surface that appeared this past June in Nature. He is also an author on the recently released study regarding the orientation and gravity of Pluto caused by this some 600 miles wide and more than 50 miles thick.

"In fact, New Horizons has detected ammonia as a compound on Pluto's big moon, Charon, and on one of Pluto's small moons. So it's almost certainly inside Pluto," McKinnon said. "What I think is down there in the ocean is rather noxious, very cold, salty and very ammonia-rich—almost a syrup.

"It's no place for germs, much less fish or squid, or any life as we know it," he added. "But as with the methane seas on Titan—Saturn's main moon—it raises the question of whether some truly novel life forms could exist in these exotic, cold liquids."

As humankind explores deeper into the Kuiper Belt and farther from Earth, this means to McKinnon the possible discovery of more such subsurface seas and more potential for exotic life.

"The idea that bodies of Pluto's scale, of which there are more than one out there in the Kuiper Belt, they could all have these kinds of oceans. But they'd be very exotic compared to what we think of as an ocean," McKinnon said.

"Life can tolerate a lot of stuff: It can tolerate a lot of salt, extreme cold, extreme heat, etc. But I don't think it can tolerate the amount of ammonia Pluto needs to prevent its ocean from freezing—ammonia is a superb antifreeze. Not that ammonia is all bad. On Earth, microorganisms in the soil fix nitrogen to ammonia, which is important for making DNA and proteins and such.

"If you're going to talk about life in an ocean that's completely covered with an ice shell, it seems most likely that the best you could hope for is some extremely primitive kind of organism. It might even be pre-cellular, like we think the earliest life on Earth was."

The newly published research delves into the creation—likely by a 125-mile-wide Kuiper Belt object striking Pluto more than 4 billion years ago—of the basin that includes Sputnik Planitia.

The collapse of the huge crater lifts Pluto's subsurface ocean, and the dense water—combined with dense surface nitrogen ice that fills in the hole—forms a huge mass excess that causes Pluto to tip over, reorienting itself with respect to its big moon.

But the ocean uplift won't last if warm water ice at the base of the covering ice shell can flow and adjust in the manner of glaciers on Earth. Add enough ammonia to the water, and it can chill to incredibly cold temperatures (down to minus 145 Fahrenheit) and still be liquid, even if quite viscous, like chilled pancake syrup. At these temperatures, water ice is rigid, and the uplifted surface ocean becomes permanent.

"All of these ideas about an ocean inside Pluto are credible, but they are inferences, not direct detections," McKinnon said, sounding the call. "If we want to confirm that such an exists, we will need gravity measurements or subsurface radar sounding, all of which could be accomplished by a future orbiter mission to Pluto. It's up to the next generation to pick up where New Horizons left off!"

Explore further

Data from New Horizons mission suggest a water-ice ocean lies beneath Pluto's heart-shaped basin

More information: James T. Keane et al. Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia, Nature (2016). DOI: 10.1038/nature20120

Tanguy Bertrand et al. Observed glacier and volatile distribution on Pluto from atmosphere–topography processes, Nature (2016). DOI: 10.1038/nature19337

F. Nimmo et al. Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto, Nature (2016). DOI: 10.1038/nature20148

Douglas P. Hamilton et al. The rapid formation of Sputnik Planitia early in Pluto's history, Nature (2016). DOI: 10.1038/nature20586

Journal information: Nature

Citation: Could there be life in Pluto's ocean? (2016, December 1) retrieved 18 October 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Dec 01, 2016
Simple answer: No. There could be no life on Pluto. Stop these fantasies. Get on with real science.

Dec 01, 2016
Perhaps this water ocean does not exist, and instead there is a layer of solid nitrogen. Solid nitrogen is denser than water ice, so it will try to sink. It would push its way down through cracks in the ice layer. Solid nitrogen is very weak and would slowly flow under pressure, serving to decouple an icy surface shell from a deep rocky core. If there was a water ammonia mixture there it could be detected by its effect on changing magnetic fields due to electric currents induced.

Dec 02, 2016
Most chemical reactions stop above the temp, Pluto is at. It's a stretch to suppose life might exist there.

Dec 02, 2016
Most chemical reactions stop above the temp, Pluto is at.

Most chemical reactions - if you remember your chemistry class in high school - are equilibrium reactions (i.e. they occur both ways). Lower temperatures do not stop them but merely change the balance. Life on Pluto could exist under these conditions (at a slow place).
Since stuff like vents aren't dependent on the distance to the sun, but can source their energy from radioactive materuials within the Planet's mantle/core, there could even be places where life exists at a 'normal' pace.

Dec 02, 2016
Simple answer: No. There could be no life on Pluto. Stop these fantasies. Get on with real science
And what would you religionists say if it turns out that life was as ubiquitous as water? It'd be like when you found out the earth wasn't the center of the universe. Or that it was round and not flat like it was described in your books.

Luckily you aren't allowed to burn scientists any more hallelujah.

Dec 02, 2016
"Simple answer: No."

Time and time again, the exploration of space has shown the simple answer is wrong. The only way we are going to truly understand what is out there is to boldly go where no one has gone before.

Dec 02, 2016
And then there is a possibility that a tiny microbe from Earth got there after an asteroid impact. Though it probably wouldn't have fared well on Pluto...

Dec 02, 2016
And then there is a possibility that a tiny microbe from Earth got there after an asteroid impact.

Probably not. The gravity well potential between Earth and Pluto is pretty large. It is far more likely that something goes from further out to further in in the solar system than the other way around. It is a lot more likely to lose momentum by a random bump with something else than to gain a push that would allow for a trip further out.

Dec 04, 2016
Maybe Pluto is a rogue planet, captured by the Sun eons ago, and originally it was belonging to a different stellar system, where a local civilization thought that Pluto would be an excellent xenobiology laboratory, so they filled that place to the brim with all kinds of lifeforms living in extreme cold, in methane and ammonia, and which right now are waiting for another species to set foot there... so they could eat something, finally.

Dec 06, 2016
@Gigel, Phys1
The Plutonian Xeno-lab was once warm and wet but they ran out of neutrons in their Neutron Repulsion (TM) core.

Dec 06, 2016
was Omatumr before your time here?

Dec 07, 2016
No that comment was a play on Gigel's post out of irony. Omatumr had this theory that the sun was made of iron or a neutron star (it changed every other post) and was powered by neutron repulsion and all the hydrogen we see are just the decay products. We've never been without cranks here, just that now they form legions.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more