The Volatility of Life

Between dust-paths
and sun-split rocks,
the scatterlings
of long-forged giants
drift.
Iron-roots burrow,
pulled through
dry flame-sleep
under night’s
unblinking stare.
Far from melting mouths,
ancient hands sift
old-world soil
for pieces still whole –
primed with silver-salt,
a clutch of bones
shaped in the quiet
years
before time began
to split.

This poem is inspired by recent research, which has used the chemical fingerprints of zinc contained in meteorites to determine the origin of volatile elements on Earth.

The origin of Earth’s essential volatile elements, such as zinc, remains a topic of debate among scientists. Volatiles are elements that can easily evaporate or escape into space, and they play a key role in shaping planets. Recent research suggests that Earth’s zinc may have come from various regions of the Solar System, as indicated by unique chemical markers in meteorites. However, many studies have overlooked meteorites from planetesimals – small, early planets that are thought to have helped form Earth. These planetesimals went through a process of melting, which caused many volatiles to escape, making it difficult to assess their contribution.

This research examines meteorites from planetesimals to better understand their role in providing zinc to Earth. By analysing the isotopic composition of zinc in these meteorites and using models to simulate Earth’s elemental makeup, researchers found that while planetesimals contributed about 70% of Earth’s mass, they only supplied 10% of its zinc. The remaining zinc likely came from unmelted, primitive materials that held onto their volatiles. This finding is significant because it suggests that such primitive materials, which did not lose their volatiles during melting, may have been essential in shaping the volatile content of planets like Earth. These results offer new insights into how planets form and develop the ability to support life.