Previous research suggests that in the early years of its life, Earth's water was ferried to the planet by asteroids, but what about the rest of the chemicals and materials, such as noble gases, that ended up being key players in the formation of life? A new study suggests that comets were the likely vehicles for these building blocks.
Noble gases are known to repel chemical reactions, which is one of the reasons that their abundance has remained the same since the formation of the Milky Way, and also why noble gas compositions on comets have remained a mystery until now.
With the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko in August 2014, researchers got their first glimpse into the composition of argon in a cometary atmosphere, suggesting that comets are a major source of the element.
Although argon does not play a significant role in everyday life, its presence on comets suggests that other prebiotic materials originated from them as well and can help scientists estimate how other materials, such as amino acids, made their way onto Earth.
The new study uses this idea to reveal that the amount of amino acids brought to the Earth by comets could be roughly the amount of total mass found in all organisms on the planet, although the calculation its still in the early stages.
"I think it's an interesting exercise," said Conel Alexander, a planetary scientist at the Carnegie Institution for Science who did not participate in the study. "But it's full of so many uncertainties. My worries are that we still know so little about comet composition."
These worries stem from the fact that the amount of argon was based on just one comet, and variability in the concentrations of cometary chemicals and materials can vary greatly between different comets.
In addition, scientists have yet to agree on a timeline for the Late Heavy Bombardment that likely brought the comets to Earth, adding to the uncertainty of the findings. Nevertheless, the new study sheds additional light on the events that led to the formation of our solar system and further research will reveal whether the new theory is an accurate representation of the early events that led to life on Earth.
The findings were published online in the March 9 issue of ScienceDirect.
