Carolyn Porco: Could a Saturn moon harbor life?

Two years ago here at TED

I reported that we had discovered

at Saturn, with the Cassini Spacecraft,

an anomalously warm and geologically active region

at the southern tip of the small Saturnine moon

Enceladus, seen here.

This region seen here for the first time

in the Cassini image taken in 2005. This is the south polar region,

with the famous tiger-stripe fractures crossing the south pole.

And seen just recently in late 2008,

here is that region again,

now half in darkness because the southern hemisphere

is experiencing the onset of August

and eventually winter.

And I also reported that we'd made this mind-blowing discovery --

this once-in-a-lifetime discovery

of towering jets

erupting from those fractures at the south pole,

consisting of tiny water ice crystals

accompanied by water vapor

and simple organic compounds like carbon dioxide and methane.

And at that time two years ago

I mentioned that we were speculating

that these jets might in fact be geysers,

and erupting from pockets

or chambers of liquid water underneath the surface,

but we weren't really sure.

However, the implications of those results --

of a possible environment within this moon

that could support prebiotic chemistry,

and perhaps life itself --

were so exciting that, in the intervening two years,

we have focused more on Enceladus.

We've flown the Cassini Spacecraft

by this moon now several times,

flying closer and deeper into these jets,

into the denser regions of these jets,

so that now we have come away with some

very precise compositional measurements.

And we have found

that the organic compounds coming from this moon

are in fact more complex than we previously reported.

While they're not amino acids,

we're now finding things like

propane and benzene,

hydrogen cyanide, and formaldehyde.

And the tiny water crystals here

now look for all the world

like they are frozen droplets of salty water,

which is a discovery that suggests

that not only do the jets come from

pockets of liquid water,

but that that liquid water is in contact with rock.

And that is a circumstance

that could supply the chemical energy

and the chemical compounds needed to sustain life.

So we are very encouraged by these results.

And we are much more confident now than we were two years ago

that we might indeed

have on this moon, under the south pole,

an environment or a zone that is hospitable to living organisms.

Whether or not there are living organisms there, of course,

is an entirely different matter.

And that will have to await the arrival,

back at Enceladus,

of the spacecrafts, hopefully some time in the near future,

specifically equipped to address that particular question.

But in the meantime I invite you to imagine the day

when we might journey to the Saturnine system,

and visit the Enceladus interplanetary geyser park,

just because we can.

Thank you.

(Applause)