I mostly work on looking at the geochemistry of planets
and what happens when they differentiate from-- when
a core differentiates-- when they differentiate from mantle
and core.
And what we are looking at is the chemistry
of how different elements partition
between the mantle of a planet and the core of a planet,
and how that happens under high pressure,
since the cores are deep in the planets.
And one of the things we can look at
to understand that process is-- we
look at the chemistry of the mantle, which
leaves a signature behind from when the metal segregates.
And so we just try to recreate that
by using these presses here-- looking at the conditions
actually in the deep interiors of the planet.
We usually start out with mixtures of oxides and metals
in proportions that we think are reasonable for compositions
of the planets.
And we put them inside the capsule,
and then when we heat them up, it
segregates into a metal portion and a silicate portion.
And then we recover that, and we study the chemistry.
They can run anywhere from a few minutes to a day or two,
depending on what we're looking at.
Well, in general, we look back at what our results tell us,
what they can tell us about the types of materials that
must have formed the planets, what sort of conditions
must have existed when the core was segregated,
and perhaps what has happened also
after the time of the segregation of the core.
So we look at different things.
Actually, currently I'm looking at some compositions-- trying
to understand the formation of Mercury.
Mercury is a very unusual planet with a very large,
proportionally, metal core, compared
to other similar terrestrial planets in the solar system--
Mars and the Earth and Venus.
And it's a mystery.
Why does Mercury have such a large core?
Is it the unique chemistry of the planet?
Is it some process that happen after the planet formed?
So yes, we look at different compositions.
So based on what we see-- compositions
of different meteorite classes that
may explain-- that we have different starting
materials or-- just different materials of what--
if we apply different conditions to the materials,
do we get-- do we end up with different compositions
of mantles and cores.
So yes, we look at not just the Earth, but all the planets.
We have lots of different meteorite classes,
and we're looking to see if any of those
make sense to be the starting materials
or could be the materials that, say, Mercury was made out of.
Use them all-- depends on what pressure I want to go to.
Right here is a piston cylinder, which we can go to two to three
GPa, which would be very, very shallow.
And then the other presses are multi-anvils where
we can go up to 25 GPa if you want to go deeper.
The interesting thing about looking at Mercury,
for example, is that the core-mantle boundary
in Mercury-- so if you want to look
at the segregation of the core-- you're
interested in what pressure the core-mantle boundary is at--
and it's only seven GPa, which makes it
a very easy and accessible planet
to study just using these presses with very
routine methods.
When you want to start looking at things that happened
in the deep Earth, well, 25 GPa only
gets you to the top of what's the segregation
of the upper and the lower mantle.
When I was young, I was always interested in astronomy.
And once I got into college, I became very interested
in geology.
And then I was very fascinated that my last year
in undergraduate school they had a course on planetary geology.
And for me, it was just combining two things
that I really loved-- outer space and geology.