Physics and chemistry of metal / silicate segregation in early Solar System planetesimals

The compositions of the planets, including the Earth, were set as they formed in a disk of dust and gas that circled the growing Sun 4.56 billion years ago. We seek to understand how our Solar System formed and evolved through time, through studying meteorite samples that arrived at the Earth's surface from space. From meteorites, we learn that many of the first small bodies (planetesimals) that formed in the Solar System were heated to the point of melting, in the first few million years after they formed. Melting allowed iron metal to sink into the centre and form a core, similar to the Earth's core. Some asteroids have high amounts of metal exposed on their surface, and these are probably the source of metal-rich meteorites such as iron meteorites. Asteroids like this show us the inside of a melted planetesimal that has had outer stony layers removed by impacts.
Our goal in this project is to understand how melting and core formation took place in these early-formed planetesimals. We will do laboratory experiments in which we melt pieces of the meteorites (called chondrites) that represent the original material of the planetesimals. We will do a set of experiments that run for different times at different temperatures. This means we can observe how metal separates from rocky material as the meteorite heats up and melts. The way metal behaves is complicated because it can change as the chemistry of the rock changes. We will look carefully at the chemistry of the metal, the rocky minerals, and the melted portion of the rock, so that we can understand how the physics and the chemistry of the system relate to each other. One of the tools for examining the shape, size and network of metal particles in the rock is X-ray tomography scanning, that shows us the inside of the sample in three dimensions. We plan to build a furnace that will fit in the X-ray scanning instrument, so that we can watch the rock melting and the metal separating out, and record videos of the process. This means that we can connect the different stages seen in the separate laboratory experiments, for a better understanding of the overall process.
The results of our project will help us understand what happened when the first planetesimals in the Solar System melted. Since the planets grew from this material, it is important to know how fast cores formed, and the way that core formation affected the chemistry of these bodies, so that we know what the Earth is made of. NASA's Psyche mission is planning to visit asteroid 16 Psyche, which has a high amount of metal inside and on its surface. At the moment, we do not know what type of meteorite is the best match for 16 Psyche's surface. Our project will help us understand how metal and rocky material came together to form this asteroid, and the processes that have shaped it into what we see today.