In a massive discovery announced yesterday in the journal Proceedings of the National Academy of Sciences, researchers from the University of Hawaii at Manoa (UH Manoa) have detected an ancient relic that comes to us all the way from the dawn of our solar system.
Among samples of interplanetary particles gathered from our planet’s upper atmosphere, the scientists uncovered interstellar dust grains that have formed 4.5 billion years ago, when the solar system was just starting out.
According to a report by Science Daily, these ancient particles are believed to have come from comets and were analyzed in a series of experiments at the Lawrence Berkeley National Laboratory in California.
The results pointed to the presence of microscopic grains called GEMS, an acronym that stands for “glass embedded with metal and sulfides,” tucked away in the collected particles of interstellar dust.
As study lead author Hope Ishii explains, these very precious GEMS are ancient remnants from before the stars and planets in our solar system were even born.
“Our observations suggest that these exotic grains represent surviving pre-solar interstellar dust that formed the very building blocks of planets and stars.”
The research combines ground-based observations of comets and their comas with 20 years’ worth of data from an instrument on board NASA’s Cassini spacecraft, called the Cosmic Dust Analyzer, notes Phys.org.
By looking at the nanoscale chemical composition of the GEMS, the team concluded that these interstellar dust components are a relic of the original material — amorphous silicate, carbon compounds, and different types of ices — that went on to form our solar system.
Although such samples cannot be found here on Earth, or anywhere in the inner solar system for that matter, since they have long been recycled as the stars, planets, asteroids, and the Kuiper Belt were churned out, some have remained trapped in the comas of passing comets, which end up distributing them throughout the solar system. This is likely how these particles ended up in Earth’s upper atmosphere: via a comet-based delivery system.
The UH Manoa team put these particles under the electron microscopes at the Berkeley Lab and discovered that the GEMS are made up of subgrains which clustered together in a low-temperature environment before the comet they likely originate from was even created.
The researchers mapped out the element distribution in the glassy grains and found that these ancient particles contain different types of carbon — an inner layer of organic carbon that acts like an adhesive and holds the GEMS together, and an outer low-density layer that encapsulates the grains’ components.
Because the type of carbon found in the inner region of the GEMS would not withstand the temperatures of the solar nebula, the scientists concluded that these particles were formed in a cooler environment in two separate stages of aggregation.
The most logical explanation is that the GEMS coalesced before our sun sparked into existence, somewhere in the molecular cloud that later became its nursery. Another possibility is that they formed on the outskirts of the protoplanetary disk that amassed around our young proto-star.
“Therefore, these interplanetary dust particles survived from the time before formation of the planetary bodies in the solar system and provide insight into the chemistry of those ancient building blocks,” says Jim Ciston, a researcher at the lab’s Molecular Foundry.
This enormous finding could shed more light into the early days of our solar system, Ishii points out.
“If we have at our fingertips the starting materials of planet formation from 4.6 billion years ago, that is thrilling and makes possible a deeper understanding of the processes that formed and have since altered them.”