Image: © NASA
Understanding how rocky planets like Earth and Mars acquired essential elements such as hydrogen, carbon, and nitrogen is crucial to learning about their habitability and development.
Meteorites, such as ordinary chondrites, offer insights into the materials that formed rocky planets. These meteorites are fragments of ancient, undifferentiated parent bodies that experienced varying degrees of heating early in the Solar System’s history, which may have completely dehydrated them.
In this study, we analyzed over 40 ordinary chondrite meteorites that experienced varying degrees of heating to measure their hydrogen, carbon, and nitrogen contents as well as their isotopic compositions. Special care was taken to minimize contamination from Earth's environment.
We found that parent body heating affected the hydrogen, carbon, and nitrogen concentrations in these meteorites, causing these elements to outgas from the interior of the planetesimal.
However, the least heated type of ordinary chondrites, known as unequilibrated ordinary chondrites, preserve small quantities of volatile-rich phases, such as hydrous minerals and organic compounds, which retain a pristine isotopic signature of deuterium (bulk 𝛿D up to +3 000 ‰).
We also used computer models to study how heat affects the ability of these meteorites to deliver water to rocky planets like Mars. Our findings suggest that most of the material that formed Mars was significantly heated, leading to only a small amount of water being delivered to the planet. However, although unequilibrated ordinary chondrites did not significantly contribute to Mars' formation, their high volatile content indicates that they may have supplied much of Mars' water.
Paper: https://www.sciencedirect.com/science/article/abs/pii/S0016703724006574