Are we alone?
That’s the question that keeps me up at night.
Not very long ago, we thought that the human and the Earth
were at the center of the universe.
Our beliefs were based on that,
we didn’t even ask ourselves if we were alone.
But over time, we started to understand that stars,
planets moved in a regular form,
there was something more complex outside Earth.
And we started asking ourselves, are we alone?
In the last decades we’ve learned
a lot about the evolution of life:
we know we come from a cloud of dust,
that cloud of dust turned into molecules,
those molecules made the soup of life;
and from that soup of life comes life and now we’re here.
If the conditions of life are so common in the universe,
i.e. coming from a cloud of dust,
the perception that we’re alone becomes a bit strange.
We have information now that would tell us it’s everywhere.
To answer this question, we have to do it in two steps.
The first step is to find out which places outside Earth could host life in them.
And the second step is, when we find those places,
see if life exists in there.
So our search is more or less oriented.
I’m lucky to work at NASA
and to be able to use very powerful tools.
I use the most powerful telescopes of space and the Earth
and we send robots to Mars, for example.
Telescopes allow us to look into the Solar System
and also outside the System, at great distances.
While robots allow us to explore
as if we were human beings with a great precision.
So let’s go to the first question:
Which places outside Earth could host life?
That’s the first base.
The thing is it’s complicated,
because our standard for life is based, obviously,
on a single one that’s the one in Earth.
But Earth has elements we have identified
as related to life, such as water.
We know oceans are rich in life, where there’s life,
there’s hydrology, there’s life forms.
Therefore, water is a very important element for us.
But in reality you only need very little water.
Our planet’s still a rock,
with a very thin layer of water.
That very thin layer of water is so important in the evolution of life
that makes it essential, but many other places can have
a very thin layer of water and be inhabitable as well.
For example, let’s think of Mars.
Mars, in fact, is very similar to Earth,
it’s big difference is in its water.
It has water that’s in polar layers in the form of ice,
but the problem of Mars is that that water is in solid state,
while in Earth we’re lucky to have it in liquid state.
Therefore, it’s not inhabitable per se.
Looking at that water with great precision,
with special instruments, I discovered Mars had an ocean
that covered it 3500 million years ago,
a great part of Mars had an ocean back then.
And over time that ocean started to disappear
and become lost in space.
When that ocean was in Mars,
life was just starting in our planet.
In the moment life was just starting in our planet
imagine something so inhabitable was going on in Mars.
We think that while part of that water escaped into space,
there’s a part that went below the surface,
so there might be inhabitable spots below the surface of Mars.
The focus of the exploration of Mars is based on studying below
the surface of Mars, looking for those inhabitable spots.
But Mars isn’t the only interesting thing in the Solar System.
Actually, we know two moons, Jupiter’s Europa and Saturn’s Enceladus,
have oceans below their surface,
in their ice cortex.
We don’t know what they’re made of,
or if they really have liquid water,
or what other type or liquid, or if it has the soup of life
like the one we need to generate life,
or what are the conditions of those places.
We know there’s something liquid below
there, but is it inhabitable?
We’re lucky that in 2019, very soon, we’re sending
the biggest and most powerful telescope to space.
That telescope will measure for us the emissions
of these oceans with great precision,
it’ll tell us what’s the composition, its gases,
if in that place the conditions for the soup of life are there or not.
We’ll be able to know with great precision
if those moons are inhabitable.
Well, we said that inside the Solar System
there’s three places that are interesting
and might have something like life in them.
So we’re already oriented, we don’t have to go to places
like Jupiter, Uranus, or others.
We have three well-defined places.
Now, the big question, how do we know if there’s life
if something is going on in the surface
or in the oceans of Europa and Enceladus.
The trick is looking for chemical changes,
the problem is chemical changes are produced by many other things.
For example, if a meteorite or a comet
strikes the surface of Mars
it’s going to liberate a chemical change, gases
that might be similar to what life might be.
Now, let’s suppose that below the surface
of Mars there’s geological activity,
this geological activity will also produce this gas
we’re looking for that might be related to life.
Now, in the most obviously interesting case,
we see this cloud of maybe methane gas, for example, in Mars —
and in this case, not in the rest,
in this case let’s imagine there’s a small bacteria that’s producing it.
The thing is how we tell which case it is.
That’s the big doubt, but there’s ways.
The key is knowing if something is going on in Mars.
How can we know if there’s methane gas in Mars?
We can do a trick, to look at light
that has components, colors.
Now imagine the light of the sun travels throughout space,
reaches Mars, is reflected in its surface,
and the atmosphere absorbs it.
If there’s gas, a molecule like methane for example, in the surface
in the atmosphere of Mars, that molecule will leave a very precise trail
in the colors of Mars, and if we have a very precise instrument,
we could measure those colors to tell if there’s methane in Mars or not.
And that’s what we are doing.
I spent four years trying all the telescopes and looking for this molecule.
And in 2009, we found it.
We found there was methane,
that in Earth is produced in 90 percent by life forms,
we found it in Mars.
Imagine the moment of the discovery.
Really, the most intense thing is that we knew it existed from 2005,
but we spent all those fours years actually validating, verifying,
so that we wouldn’t be wrong
as it had big implications
on the exploration of a planet like Mars.
The discovery was so radical
that it changed how we now explore Mars.
All the space agencies, NASA, the European Space Agency,
the Japanese and all the rest, are now focused
on finding out how can we know what’s going on
and if we can measure these zones of activity
that might be related to biological activity.
And when we see who can produce methane gas,
we think of very simple things, the most likely.
Radiation, water, carbon dioxide,
a small bacteria consumes this
and produces a spacial methane flatulence.
That’s the prototype of what we think of,
when we think about life outside Earth.
we’re thinking of this.
And why are we thinking of this?
Because it’s the most simple, and probably also the most likely.
That’s the big search.
The thing about these two very important discoveries,
is that first, we know that in the past
Mars was inhabitable or much more inhabitable than what it is now,
maybe it had big zone where something was happening, maybe life.
Maybe that methane we’re looking at now
is a residuary of the life that was produced,
that was formed 3500 million years ago
and is below the surface acting and emitting those gases.
But if the past of Mars is interesting
what’s most interesting is its future.
We’re now working intensely to send human beings to Mars.
And I believe that in the next 10 or 20 years, all of us here
will see a human walk on the surface of Mars.
(Applause)
Everything I told you,
all these research that’s so hard to do with robots,
with remote measuring, we’ll be able to do them there,
human beings will be able to do these missions
and search and explore what’s really going on in Mars.
Is there something outside the Solar System?
I mean, that search for life, too —
What happens outside the Solar System?
A lot happens.
In the last two decades, we’ve discovered
more than 500 exoplanets
or planets that are outside the Solar System in our galaxy.
I mean, imagine the possibilities.
They come in all sorts of colors and types,
some form very interesting planetary systems.
Some of them are very similar to Earth.
If we’ve discovered that in the last two decades,
imagine the possibilities.
And that’s what keeps me up at night, knowing if we’re alone.
And I’m convinced that we’re very close to knowing it.
Thank you.
(Applause)
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