The mysterious meteorites that helped form Earth
Anew study led by researchers at the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology suggested that these asteroidal materials might have formed very far out in the early solar system then been transported into the inner solar system by chaotic mixing processes.
The study was published in the journal, 'AGU Advances.' Our solar system is believed to have formed from a cloud of gas and dust, called the solar nebula, which began to condense on it gravitationally 4.6 billion years ago. As this cloud contracted, it began to spin and shaped itself into a disk revolving about the highest gravity mass at its centre, which would become our Sun.
Our solar system inherited all of its chemical composition from an earlier star or stars which exploded as supernovae. Earth is believed to have formed partly from carbonaceous meteorites, which are thought to come from outer mainbelt asteroids. Interestingly, though several lines of evidence suggest carbonaceous meteorites are derived from such asteroids, the meteorites recovered on Earth generally lack this feature. The asteroid belt thus poses many questions for astronomers and planetary scientists.
In this study, a combination of asteroid observations using the Japanese AKARI space telescope and theoretical modelling of chemical reactions in asteroids suggests that the surface minerals present on outer main-belt asteroids, especially ammonia (NH3)-bearing clays, form from starting materials containing NH3 and CO2 ice that are stable only at very low temperature, and under water-rich conditions.
To understand the source of the discrepancies in the measured spectra of carbonaceous meteorites and asteroids, using computer simulations, the team modelled the chemical evolution of several plausible primitive mixtures designed to simulate primitive asteroidal materials. They then used these computer models to produce simulated reflectance spectra for comparison to the telescopically obtained ones.
This study suggested the materials that formed the Earth may have formed very far out in the early Solar System and then been brought in during the especially turbulent early history of the solar system.
—ANI