>>Jakob van Zyl: Ladies and gentlemen, I'm going to talk to you a little bit about a
question that humans have been asking for thousands of years: Are we alone?
And I'm not talking about those humans that walk around talking to an imaginary friend
because they like intelligent conversation.
We are going to look at some other planets and see if there may be life elsewhere besides
the Earth.
So the theory tells us that planets form out of the so-called debris disk of material that's
leftover once a star is born.
And over time, little pieces of this debris disk coalesce into larger and larger chunks,
basically, until they become big enough to become planets.
Now, we know that there are three main ingredients that are required for life to exist.
That's liquid water, the conditions so that organic molecules can form, and some form
of energy that can sustain metabolism.
Now, since the solar system is in thermal equilibrium, there is a well-defined distance
away from a star where the temperature would be such that liquid water can exist all the
way from just below boiling point on the one hand to just above freezing point on the other
hand.
And that region is called the habitable zone.
And that's where theory says we should look for the signs of life.
Now, we'll get back to that in a little while.
For our solar system, the habitable zone stretches from just inside the orbit of Venus to just
outside the orbit of Mars.
Now, the temperature on Venus to date is hot enough to melt lead so finding liquid water
there is very unlikely.
And that is not because it is not in thermal equilibrium, it is because Venus has a very,
very thick atmosphere and has a run-away greenhouse effect going on.
So let's skip to the other end of the habitable zone, to the planet Mars.
Now, some of you may have heard that we had a rather spectacular landing on the surface
of Mars in August of last year.
And if you were here yesterday, you saw a few snippets of a video of that landing.
So here we go.
[ Video playing ] [ Video ends ]
>>Jakob van Zyl: Even nerds can get excited.
Well, there she is.
Curiosity on the surface of Mars after traveling around 500 million kilometers in eight months.
Curiosity carries 10 very sophisticated instruments, and it is basically a roving chemical laboratory.
One of the main questions we wanted to answer with this machine was whether the conditions
on Mars were ever such that it could have supported life.
Now, curiosity carries a drill with which it can drill some holes into rocks so we can
look at the interior of the rocks.
Here you see a photograph of the first two holes ever drilled into a rock on a different
planet.
Curiosity then scooped up some of that gray material that came out of the rock and placed
it into two of the instruments inside the belly of the rover for further analysis.
And the results very clearly showed that the conditions in Gale Crater where we landed
could have supported life.
In fact, humans would have been able to drink the water in which those rocks formed, but
that's not all.
This series of images taken with one of our spacecraft orbiting around Mars shows those
streaks forming during a martian summer and then retreating and disappearing again at
the end of the summer.
The theory is that those are seeps of briny water that form where the ice in the martian
crust is close enough to the surface that it can actually melt during the summer.
So the important point is there is liquid water on the surface of Mars today, even though
it may be in limited quantities.
But this conference challenges us to reset and rethink.
So let's leave the comfort of our habitable zone and venture further out in our solar
system to the next and largest planet in the solar system, Jupiter, shown here with its
moon Europa in front of it.
The close-up look of Europa shows a surface that has very few impact craters on it.
And, in fact, what that means it is a relatively young surface.
In fact, the surface of Europa is dominated by these linear features that appear like
cracks.
The entire surface of Europa is, in fact, an ice crust that's between 10 and 20 kilometers
thick.
And underneath that ice crust is a liquid ocean, most likely salty because it has a
magnetic field so we can tell it has to be salty.
And it is estimated to be about 100 kilometers deep.
Now, keep in mind, on the Earth, the deepest point in our ocean is only about 11 kilometers.
So what keeps this ocean in its liquid state?
Well, it's tidal flexing.
As Europa orbits around Jupiter, the tides that this large planet forms inside this moon
actually keeps it -- the ocean in a liquid state.
So here is the relative sizes of Europa and the Earth.
Europa is slightly smaller than our moon.
Also shown by those two little water bubbles is the relative amount of water on these two
bodies.
So even though Europa is much, much smaller than the Earth, it may very well be the body
in our solar system that has the most water on it.
So liquid water, salty water, and heat.
Definitely a place we should go look further for the signs of life.
Let's move out further to the second largest planet in our solar system, Saturn, shown
here with its spectacular rings as photographed by NASA's Cassini spacecraft.
Saturn has more than 60 moons around it.
And one of them in particular called Enceladus turned out to be a very interesting object.
On one of its orbits around Saturn, Cassini took this picture of Europa that shows what
appears to be four plumes coming out of the south pole region of that moon.
So we challenged our navigators to bring the spacecraft as close as possible to that moon
so we can take a better look at those plumes.
And they responded by flying 25 kilometers above that surface of that moon.
Not bad considering that Saturn is more than a billion kilometers away from us.
And they actually flew the spacecraft through those plumes.
So we were actually able to measure that those plumes are actually geysers of water vapor
that shoot out of that moon to several hundred kilometers in the air, by the way.
And not only does it contain water vapor, it contains complex organic compounds.
Another world where we have liquid water, organic compounds, and heat from tidal flexing.
You can see here a closeup of that moon.
The plumes come out of those linear cracks in the bottom of this moon.
So yet another place that we should go back to and look for some signs of life.
These examples illustrate that there are as many places in our solar system outside of
the habitable zone where we should be able to find life as there are inside the habitable
zone.
But what about all the space outside of our solar system?
Could there be planets out there that could harbor life?
Well, it's unfortunately very hard to make good pictures of planets that are very far
away.
Here's a picture of the Earth.
Now, there is nothing wrong with your eyes.
It is a crappy picture.
It is 160-kilometers resolution to prove a point.
If you were to take the Earth and you move the Earth to the nearest star to our sun,
a tiny four light years away, you would need a telescope 15,000 times the size of the Hubble
space telescope to make this crappy picture of it.
So there is no way we can launch a telescope that size.
By the way, the (indiscernible) would cover the greater London.
That's how big that telescope.
So -- but, fortunately, there are indirect ways in which we can find planets around stars.
One is shown here.
Every time a planet comes between us and its parent star, it blocks a little bit of the
light from that star out.
So the star appears to go dimmer for a little while and then it comes back bright again.
And this process repeats itself every time when this planet comes between us and its
parent star.
So NASA built a special 100 megapixel camera, put it in a medium-sized telescope, and launched
what is called the Kepler mission in 2009.
Now, Kepler stares at the same 150,000 stars every second and looks for those little dimming
events to determine whether there are planets around those stars.
And as of January this year, the Kepler team announced that they have found 2,740 candidate
planets around more than 500 stars, ranging from ones much, much larger than our sun to
ones only about a tenth of the size of our sun.
Now, you might say why 500 out of 150,000?
Keep in mind Kepler can only see those planets that come between us and their parent stars.
Only certain orbits will do that for us.
There may be many more orbits, planets, out there that are just such that they don't come
between us and their parent star.
Now, I know there's some people that say there are lies, there are damn lies, and there are
statistics.
But if you take the statistics of random orbiting into account and combine it with the results
from Kepler, the team estimates that there are at least 50 billion planets -- billion
with a B -- planets in our Milky Way galaxy alone.
And of those, 500 million of them are in the habitable zones of their stars.
Suddenly our solar system don't look nearly as unique as it did ten minutes ago.
So, the question: Are we alone?
I don't know.
I will let you be the judge of it.
All I can say is that I hope that in my lifetime, we will see somebody, you know, find a biosignature
somewhere else in the universe.
Thank you for your time.
[ Applause ] >>David Rowan: So, Jakob, if we have established
there needs to be water up on Mars, what do you look for then next?
>>Jakob van Zyl: Well, we want to look for possible signs of past life.
So, as I said, Curiosity carries 10 very sophisticated instruments, instruments that are -- would
be sophisticated if they were in your laboratory on Earth, in fact.
And so what we are going to do is drive up this mountain where we landed.
There is a mountain that's about 3 kilometers high very close to where we landed.
And we are going to drive up that mountain.
That mountain is made of layered material.
So layered material means we're going back in the history of Mars.
So we can look over the history of Mars, sample rocks as we go, to see if there was ever a
time in Mars where we could find maybe signs of past life.
>>David Rowan: So Google talks a lot about moonshots.
But Elon Musk with SpaceX is talking about doing a Mars-shot.
His Dragon going up to the spacestation he sees just as a learning experience because
he wants to settle Mars.
When's that going to happen?
>>Jakob van Zyl: Well, you know Elon from the beginning has said the reason he is building
rockets is to go to Mars.
In fact, we work with him since we know how to land there.
He wants to go there.
He has the rockets.
We don't.
That sounds like a pretty good partnership.
There are lots of obstacles to overcome.
Going there is not the hard part.
Bringing people back is the hard part, especially if you are going to land on the surface because
you have to create the technology to build a rocket on the surface of Mars so you can
launch people back into space and bring them back.
Now, people like me might actually volunteer to just go there and stay there.
But, you know, most people want to come back.
I bet, though, if Google decides to have Zeitgeist on Mars, a lot more people would like to go
there.
>>David Rowan: We'll be taking a list of early volunteers after this.
[ Laughter ] >>David Rowan: Thank you very much, Jakob
van Zyl.
>>Jakob van Zyl: Thank you very much.
[ Applause ]