Not just water. Nitrogen may have arrived on Earth via meteors
Nitrogen compounds are common in the extreme regions of the Solar System but are less prevalent at its center. So how did this element become so abundant on Earth? An international research team led by the University of Kyoto sought to answer this question.
3:45 PM EST, December 2, 2023
Many scientists hypothesize that our planet's water originated largely from icy comets that delivered it to early Earth, potentially even carrying life particles. Samples from the asteroid Ryugu, brought to Earth by a Japanese mission, have sparked additional theories about the origins of this life-sustaining substance. Now, these same Ryugu samples may also shed light on another compound integral to life on Earth. Nitrogen may have come to us courtesy of micrometeor bombardment.
Is there nitrogen on Ryugu?
Nitrogen compounds, such as ammonium salts, typically form in regions distant from the Sun. Findings by University of Hawaii scientists participating in the research suggest that large amounts of nitrogen compounds could have been transported to neighboring Earth early in its existence. These elements may have served as components of the initial ingredients for life.
Their collection facilitated research on Ryugu samples via the Hayabusa2 space probe, owned by the Japan Aerospace Exploration Agency (JAXA). This probe studied the asteroid and in 2020, brought material from its surface back to Earth. Ryugu orbits the Sun along a larger and more inclined path than Earth's and has experienced intensive cosmic weathering due to solar wind and micrometeor bombardment. According to research-based hypotheses, these micro meteors may be the reason for the presence of iron nitride particles in Ryugu's material.
Nitrogen in the Solar System
Scientists believe that nitrogen compounds reached Ryugu from icy heavenly bodies orbiting on the outer edges of our Solar System. Micrometeor collisions with Ryugu's surface—which is primarily composed of iron and carbon—initiate chemical reactions in magnetite that result in the formation of iron nitride, suggests Toru Matsumoto, the study's lead author from the University of Kyoto.
When magnetite (an iron oxide mineral) is exposed to the cosmic vacuum, it loses oxygen atoms from its surface due to them being "blown off" by solar winds. Collisions with micro meteors further heat the material's surface, leading to the creation of metallic iron. This metallic iron readily reacts with ammonia, creating conducive conditions for the formation of iron nitride.
