Is it snowing microbes on Enceladus?

Mar 28, 2012 By Dauna Coulter
Dramatic plumes, both large and small, spray water ice from many locations near the south pole of Saturn's moon Enceladus. More than 30 individual jets of different sizes can be seen in this image captured during a flyby of NASA's Cassini spacecraft on Nov. 21, 2009.

There's a tiny moon orbiting beyond Saturn's rings that's full of promise, and maybe -- just maybe -- microbes.

In a series of tantalizingly close flybys to the moon, named "Enceladus," NASA's Cassini spacecraft has revealed watery jets erupting from what may be a vast underground sea. These jets, which spew through cracks in the moon's icy shell, could lead back to a that is uniquely accessible in all the .

"More than 90 of all sizes near Enceladus's are spraying , icy , and all over the place," says Carolyn Porco, an award-winning and leader of the team for ’s . "Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth's oceans."

Thermal measurements of Enceladus's fissures have revealed temperatures as high as -120 deg Fahrenheit (190 Kelvin). "If you add up all the heat, 16 gigawatts of thermal energy are coming out of those cracks," says Porco.

She believes the small moon, with its sub-surface liquid sea, organics, and an energy source, may host the same type of life we find in similar environments on Earth.

The watery plumes of Enceladus come from icy fissures nicknamed "tiger stripes."

"The kind of ecologies Enceladus might harbor could be like those deep within our own planet. Abundant heat and liquid water are found in Earth's subterranean volcanic rocks. Organisms in those rocks thrive on hydrogen (produced by reactions between liquid water and hot rocks) and available carbon dioxide and make methane, which gets recycled back into hydrogen. And it's all done entirely in the absence of sunlight or anything produced by sunlight."

But what makes Enceladus special is that its habitable zone offers itself up for easy access.

"It's erupting out into space where we can sample it. It sounds crazy but it could be snowing on the surface of this little world. In the end, it's is the most promising place I know of for an astrobiology search. We don't even need to go scratching around on the surface. We can fly through the plume and sample it. Or we can land on the surface, look up and stick our tongues out.  And voilà…we have what we came for."

The source of Enceladus's heat appears to be Saturn itself. Researchers say Saturn's gravitational pull causes the moon's shape to change slightly on a daily basis as it orbits. Flexing motions in its interior generate heat--like the heat you feel in a paperclip when you bend it back and forth rapidly.

"But the tidal flexing occurring now is not enough to account for all the heat presently coming out of Enceladus. One way out of this dilemma is to assume that some of the heat observed today was been generated and stored internally in the past."

Porco believes Enceladus's orbit could have been much more eccentric, and the greater the eccentricity, she says, the greater the tidal flexing and resulting structural variations that produce the heat. In this scenario, the heat would have been stored inside the little moon by melting some of the ice to recharge the liquid sea.

"Now that the orbit's eccentricity has lessened, the heat emanating from the interior is a combination of heat produced today and in the past.  But since more heat is coming out presently than is being produced, Enceladus is in a cooling off stage and the liquid water is returning to ice. There are models to show that it never really freezes entirely, so the eccentricity may increase again, restarting the cycle."

Whatever is turning up the heat, Porco has a plan of action. It's simple:

"We need to get back to Enceladus and check it out."

Explore further: The wake-up call that sent hearts racing

Related Stories

A fizzy ocean on Enceladus

Jan 27, 2011

For years researchers have been debating whether Enceladus, a tiny moon floating just outside Saturn's rings, is home to a vast underground ocean. Is it wet--or not? Now, new evidence is tipping the scales. ...

Cassini sees Saturn stressing out Enceladus

Mar 20, 2012

(PhysOrg.com) -- Images from NASA's Cassini spacecraft have, for the first time, enabled scientists to correlate the spraying of jets of water vapor from fissures on Saturn's moon Enceladus with the way Saturn's ...

Recommended for you

The wake-up call that sent hearts racing

1 hour ago

"But as the minutes ticked by, the relaxed attitude of many of us began to dissolve into apprehension. Our levels of adrenaline and worry began to rise."

US-India to collaborate on Mars exploration

11 hours ago

The United States and India, fresh from sending their own respective spacecraft into Mars' orbit earlier this month, on Tuesday agreed to cooperate on future exploration of the Red Planet.

Swift mission observes mega flares from a mini star

11 hours ago

On April 23, NASA's Swift satellite detected the strongest, hottest, and longest-lasting sequence of stellar flares ever seen from a nearby red dwarf star. The initial blast from this record-setting series ...

Sandblasting winds shift Mars' landscape

16 hours ago

High winds are a near-daily force on the surface of Mars, carving out a landscape of shifting dunes and posing a challenge to exploration, scientists said Tuesday.

PanSTARRS K1, the comet that keeps going

18 hours ago

Thank you K1 PanSTARRS for hanging in there! Some comets crumble and fade away. Others linger a few months and move on. But after looping across the night sky for more than a year, this one is nowhere near ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

sstritt
4.2 / 5 (5) Mar 28, 2012
Low hanging fruit! Europa doesn't look so appealing anymore.
that_guy
3 / 5 (4) Mar 28, 2012
Too much talk. Drill baby, drill (On Enceladus)
Howhot
not rated yet Mar 28, 2012
What a weird looking planet. I mean Weird! One side is cratered with deep impacts, the southern pole has a large plate up lifted and the southwest is folded like there is a buried ocean, and to the west it looks like there is a very large impact crater that has been filled in with ICE?

It always amazes me what Cassini is turning up.
Torbjorn_Larsson_OM
not rated yet Mar 29, 2012
I used to be very skeptic to the astrobiology claims re Enceladus, since the samples (to the resolution of the small mass spec) looks like cometary pristine organics. However the later models seems to put down the plume ejecta to emanate from secondary molten water pockets in the near surface ice, so it looks good so far.

Of course bacteria would be blown out, they may not have time to process the organics as in the deep and (now known as) old ocean. So I'm hip with a better sample.

And let's hope no other deep space probes are sent out with a low mass, low resolution mass spec! Tantalizing hints, but poor data.