New isotope tracers of rocky planet forming environments

Introduction

The plethora of Earth-like exoplanets indicates that planet formation is efficient, highlighting the need for unraveling the pathways to forming habitable worlds. The new planet-formation paradigm, i.e. pebble accretion, suggests that mm-to-cm sized pebbles are the main planetary building blocks as opposed to colliding proto-planetary bodies.

Background

Bulk samples of meteorites from asteroids, leftovers from the early Solar System, have long been used to infer the nature of Earth’s precursor material. However, pebble accretion predicts that pebble-like components of primitive chondrite meteorites provide a more accurate record of the precursor material to terrestrial planets, including the source of volatiles critical to life.

Chondrules and Their Significance

The most abundant chondrite constituents are mm-sized chondrules, hypothesized to be the pebbles driving planet formation. Chondrules formed within 5 Myr of the Solar System thus represent time-sequenced samples that can probe the nature of the matter, including its environment(s), that accreted to rocky planets.

Research Objectives

We will elucidate the origin and history of the matter precursor to terrestrial planets by studying:

1. Chondrules
2. Matrix components
3. Refractory components in chondrites

This information is key for understanding the initial conditions allowing the formation of Earth-like planets.

Methodology

Combining isotope fingerprinting, age-dating, and petrology, our data will be obtained using state-of-the-art techniques, including:

• Next generation collision cell mass spectrometry
• Thermal ionization mass spectrometry
• High-resolution imaging

Goals and Expected Outcomes

We will identify the precursor matter to terrestrial planets and probe how its composition varied in space and time. Additionally, we aim to:

1. Identify the disk environment where the primordial population of planetesimal seeds formed
2. Evaluate the role of thermal processing and outward recycling in modifying inner disk matter

With these goals, including high-risk high-gain ventures, we are in a strong position to make step-change discoveries in cosmochemistry.