A comet strike on Pluto hints it may be hiding a giant, habitable ocean

An illustrated timeline of
how an asteroid formed Pluto’s heart-shaped Sputnik Planitia
basin.

James Tuttle Keane;
Shutterstock; Dave Mosher/Business
Insider

Two new studies of Pluto suggest the enigmatic ice ball was
walloped by a giant asteroid, and that it is hiding a very big
secret: liquid water.

If two groups of scientists are correct, Pluto isn’t frozen solid
some 3 billion miles away from the sun. Instead, trapped beneath
layers of frozen nitrogen and water ice, it probably has a

subsurface ocean blended with alcohol, ammonia, and other
antifreeze chemicals.

“Pluto, once a planet, then a dwarf planet, may now soon also
adopt the moniker of ‘ocean world’,” Kevin Hand, a
planetary scientist at NASA JPL who wasn’t involved in the
research, told Business Insider.

Researchers, who describe their findings in two
new
studies in Nature, came to this conclusion after looking closely
at photos beamed back by NASA’s New Horizons mission, a
nuclear-powered probe that
zoomed past Pluto in July 2015.

Those first-ever images of Pluto revealed a 325,000-square-mile,
heart-shaped basin of nitrogen ice, called Sputnik Planitia, that
was littered with cracks and fissures.

Computer analysis of the feature and Pluto’s orbit suggested
something was off: Given the way Pluto interacted with its moon
Charon, there should be a lot more material located at Sputnik
Planitia.

A cutaway illustration of
Pluto. A global, liquid water ocean likely exists beneath the
dwarf planet’s icy shell.

Pam
Engebretson/UCSC

“It’s a big, elliptical hole in the ground, so the extra weight
must be hiding somewhere beneath the surface. And an ocean is a
natural way to get that,” said Francis Nimmo, a planetary
scientist at University of California Santa Cruz (UCSC), in a
UCSC
press release.

Back in November 2015, scientists announced their belief that
Sputnik Planitia was created by a giant
asteroid strike, which blasted away huge chunks of Pluto’s
water-ice crust.

The new studies add to this idea, noting the catastrophe must
have happened within the past 4 billion years and that the impact
site was originally more than 4 miles deep.

The giant scar has since sprung back and partly filled in with
dense and heavy nitrogen ice, they found. Researchers also
figured out with computer models that Pluto’s internal tides with
Charon can’t be explained if the world was solid all the way
through.

“We tried to think of other ways to get a positive gravity
anomaly, and none of them look as likely as a subsurface ocean,”
Nimmo said in the release.

Steven
Vance, an astrobiologist and geophysicist who’s working on
NASA’s mission to Europa — another ocean world, this one orbiting
Jupiter — expressed no doubt Pluto indeed has an ocean.

“A subsurface liquid ocean makes sense, given nitrogen’s
insulating properties,” Vance told Business Insider.

A different kind of alien life?

NASA/JHUAPL/SwRI

But the probable discovery of Pluto’s ocean leaves open another
question: What about alien life?

Vance said he’s “curious about the ocean’s composition,” noting
it’s probably kept liquid at very cold temperatures by a lot of
ammonia.

“It’s possible the ocean also contains alcohols (methanol,
ethanol), hydrocarbons (methane, ethane), and more complex
molecules made from [carbon, nitrogen, hydrogen, and oxygen] that
are so abundant on Pluto,” he said.

Hand said these chemicals also make Pluto “interesting in the
context of habitability.”

“Nitrogen is a critical element for life as we know it and
Pluto’s putative ocean could be a source of both liquid water and
nitrogen,” Hand said. “When searching for life beyond Earth we
have long ‘followed the water’, but we also need to ‘follow the
carbon’ and ‘follow the nitrogen’ – Pluto may combine all three.”

Hand wouldn’t go so far as to say the dwarf planet could support
life, but it might raise the chances of finding it elsewhere in
the solar system or the Milky Way.

“I wouldn’t rule out similar oceans on other dwarf planets,”
Vance said. “Considering the prospects for life in such places is
similar to stretching our imagination to think of life in Titan’s
surface lakes or its subsurface ocean.”

While scientists ponder the chemistry of Pluto’s new watery
realm, New Horizons will
keep on flying toward its next exotic and icy destination —

the Kuiper Belt Object 2014 MU69 — at a blistering pace of
32,000 mph. It should reach the 30-mile-wide object in January
2019.