(peaceful music)
- When I was a kid looking up at the stars,
I really always wondered how did we get
here and are we alone?
My name is Bethany Ehlmann.
I'm a professor of planetary science at Caltech
and Research Scientist at the NASA
Jet Propulsion Laboratory.
I remember when I was six, I declared that I wanted
to be an astrophysicist like Steven Hawking.
And I'm not an astrophysicist, but I am an explorer
an explorer of planets of asteroids,
and I really enjoy the unknown in space exploration.
We're going places that really,
no one has gone before.
And it's one of the few types of science
where you can do that.
Our solar system is about four and a half billion years old
and asteroids formed within the first few million years
that the solar system existed.
Asteroids are mostly metal and rock and ice,
and are thought to be the shattered remnants of planets.
They're these bank vaults full of information
about what conditions were like early in the solar system
as planets were forming.
What we're looking at here is the largest asteroid
in the asteroid belt and we're able to have
this amazing view because of the Dawn spacecraft mission,
which orbited Ceres for several years.
- [Announcer] Main engine start, one, zero,
and lift off of the Delta II rocket lift off.
- The Dawn mission was a spacecraft that was launched
in 2007 and it was designed to study Ceres,
which is the largest asteroid in the asteroid belt.
And, it's actually not just an asteroid.
It's a dwarf planet.
(upbeat music)
One of the most fascinating things about Ceres
that we discovered is it wasn't a uniform grey.
Some parts of the surface had these amazing brighter spots.
Here you can see one of them coming out of the crater.
This was totally unexpected.
One of the fun parts of being a planetary scientist,
and especially my job, is that I have a laboratory
where we get to measure the spectroscopic signatures
of rocks and minerals.
Every material has a characteristic way
that it reflects light.
We can call this a spectral signature.
And so one of the things that we can do is here on Earth,
we can measure the spectral signatures of all sorts
of materials that we know exactly what they are.
And then we can compare those signatures
to the reflected light we get from asteroids
to figure out what those objects are made of.
Now on Ceres we basically repeat the measurement,
but our spacecraft is the sensor,
instead of my lab instrument.
And the source, instead of a halogen light
in the lab, is the sun.
And so by comparing those materials
in the lab to the materials the we see on other planets,
that's how we know what planets and asteroids are made of.
When we looked at the data, we found
that these bright spots were actually made of salts,
and these salts were being pulled up by impacts.
So, salts, underneath the surface of Ceres?
What did that mean?
That meant that there were salty waters
underneath Ceres at some period of time.
Maybe even a salty ocean, deep underground.
What past underground waters tells us on Ceres
is that Ceres was once wet.
And because other asteroids are like Ceres, water rich,
that tells us that some of the asteroids
that were hitting Earth early in its history
were probably delivering some of the water
that's found on our planet today.
One of the key questions about asteroids
is did the play any role in the origin of life?
Asteroids brought water and carbon,
some of the most important ingredients for life,
to our planet very early in its history.
Did they help make earth this amazing
habitable place it is today?
We don't fully know the answer.
We think they played a role, but that's one
of things were trying really hard to figure out right now.
(majestic music)
So these are some of the reasons that I explore,
is curiosity and a desire to learn things
that no one yet knows.