AGU

Every year the American Geophysical Union (AGU) hosts a conference which gathers more geoscientists into one place than any other event in the world (more than 24,000 geoscientists attend every year).  This week-long conference allows geoscientists from around the world to present their research, hear about the latest cutting edge research being done, and talk with other geoscientists, some of whom are the leaders in their field.  Last year I attended for the first time and was awed by the enormous amount of research presented.  This year I got to present some of my own.

The poster hall.  Every day 3,000 are presented for the entirety of the conference (15,000 total!)

On the floor of the poster hall.  Presenting research in this format allows for casual conversation with others and lets us gain new insights, receive critiques, and ask questions.    

Me at my poster.  Of the people that talked to me about my work 3 of them were anonymous judges for a student presentation competition   

In addition to posters nearly 7,000 lectures are given throughout the week.  This one, given by Secretary of the Interior Sally Jewell, was on the importance of making science understandable to the public.   

The exhibition hall is a place where vendors can show off their scientific equipment 

NASAs booth is always one of the most popular.  In addition to giving talks on their projects they also have interactive displays which showcase their many scientific accomplishments.  Their free calendars are also in high demand! 

I had an amazing time at the conference.  I was able to talk to other scientists about their research, listen to amazing talks, and learn new things about both my field of study as well as ones I'm not as familiar with.  A big highlight for me was watching two scientists with previously opposing views give back-to-back lectures during which they were able to solve the differences in their research.  Already can't wait for next year!     

  

Drinking Planets

A few weekends ago UCLA hosted Exploring Your Universe, a one day science fair aimed at getting students K-12 excited about science.  Dozens of booths with demonstrations and experiments were set up by the Physics, Chemistry, Astronomy, Biology, Atmospheric, and Geology Departments.  While the Mineral Physics lab didn't host a booth this year I volunteered at a booth hosted by another lab in the geology department, the SPINlab.

The SPINlab studies how fluids move within planetary bodies and their atmospheres. Because planets rotate about their axis it can be difficult to predict how liquids, like the outer core of Earth or the dense atmosphere of Jupiter will behave.  In comes the SPINlab which uses rotating tanks of liquids to model these effects.  You can learn more about the SPINlab and see videos of their experiments at: http://spinlab.ess.ucla.edu

While the SPINlab had a variety of amazing demonstrations (which can be seen on their website!) I volunteered at their Drinkable Planet demonstration.  At this booth we were teaching planetary differentiation in a rather unconventional way: with juice!

Every planet in the solar system today has layers, but in the very beginning of the solar system when planets were forming they were a jumble.  However, as time passed planets started differentiating (or separating) based on the densities of the different rocks.  The densest, heaviest rocks were pulled down by gravity to the center of the Earth while lighter ones stayed on the surface.  That's why we have a core made of iron and other heavy metals, a mantle of medium density metals and nonmetals, and a crust of mostly light nonmetals (this is an over simplification!).

Turns our freshly blended juice acts the same way.  The juice will sink to the bottom, the pulp will rise to the center, and the frothy foam will float to the top.  Armed with two juicers and $200 worth of fruits and vegetables we made fresh juice for hundreds of kids demonstrating how the mixture would separate with time, just like a planet.  We then encouraged the kids to watch and see for themselves before drinking their planet.  

 

Setting up the drinkable planet station

A differentiated cup of juice with light foam on the top, medium pulp in the middle, and heavy juice on the bottom

Mineral Physics

The center of the Earth lies 6,353-6,384 kilometers (3,947-3,968 miles) beneath your feet.  Depending on where you live (and more specifically the altitude), if you were to travel there you would have to pass through 0-40 km of crust, 660 km of upper mantle, 2,200 km of lower mantle (which, despite popular belief, is not molten), 2,080 km of outer core (which is molten), and 1,390 km of solid inner core.  Despite knowing this, no one has ever traveled to the center of the earth.  The deepest we have ever drilled is a mere 15 km and the deepest rock samples we have only come from a depth of 400 km.  So how do we know so much about the interior of our Earth?

My quick guide to the deep Earth

It turns out earthquakes are able to tell us a lot about the deep Earth. While earthquakes only occur in the upper 750 km of the Earth, the waves they generate can travel all the way to the core.  As these waves move through Earth’s layers they speed up, slow down, or rebound depending on the density of the layer.  This allows seismologists (geologists who study earthquakes) to measure the thicknesses and densities of the layers based on the speed of the wave.     

While this is a good start to understanding the interior of the Earth there are still many mysteries that remain.  We don’t know the exact composition of the different layers or how they might interact.  In fact, the 5 layer model of the Earth described above is an oversimplification.  There are other structures that exist within the Earth but are poorly understood such as the D” layer near the core-mantle boundary and the large low shear velocity provinces (LLSVPs) in the lower mantle.  Seismologists can show these features exist but can’t explain why.

That's where mineral physics come in.  Mineral physics is a relatively new branch of geology that falls under geochemistry and geophysics.  It studies the material properties of minerals at the high pressures and temperatures found within the Earth.  Because we can't measure these conditions directly we use lab experiments that simulate these conditions instead.  In my own research I use powerful lasers to create the high temperatures found within Earth and diamond anvil cells (DACs) to create the high pressures.  As the name suggests, a DAC uses two diamonds, similar to those found in jewelry, with the pointy ends facing each other.  Samples are placed on the tip of the diamonds which are then squeezed together to generate high pressures.  Using this method, we can create pressures exceeding 200 billion pascals which roughly correlates to the very center of the Earth (just one billion pascals is roughly equivalent to nearly 5 miles of cars stacked on top of each other).   

A loaded DAC, this one is at 53 billion pascals (note penny for scale)

An unloaded DAC with diamonds (mounted on a metal backing plate in center front) taken out

One of our diamonds under the microscope

These techniques have given us special insight into the composition and physical properties of the interior of our Earth.  Experiments have discovered a phase transition in an abundant mineral in the lower mantle at the same pressures and temperatures as the D" layer.  Because a phase transition changes the structure and therefore the density of the mineral it can explain why we observe a change in seismic velocities near the D" layer. 

Experiments also allow us to study how elements cycle through our Earth such as carbon, oxygen, hydrogen, nitrogen, and sulfur.  High pressure and temperature studies of minerals containing these elements tell us where in the Earth they might be stable, what phase transitions they might undergo, how much might be stored within the Earth, how much enters the deep Earth, and how much is released every year.  During my undergraduate research I studied the mineral Anglesite (which contains sulfur) at high pressures.  We currently don't know how much sulfur is in the deep Earth but it is estimated to contain around 90% of Earth's total.  My experiments found two phase transitions in Anglesite which made it more stable at high pressures.  However, there is still a lot of research to be done before we completely understand how sulfur and other elements cycle through our Earth so stay tuned for more about my current research!

A sample of Anglesite.  For my experiments a microscopic piece was broken off to load into the DAC