The origin of life on Earth may have partly been due to comets. Scientists have shown that ribose, a sugar that's one of the building blocks of genetic material in living organisms, may have formed in cometary ices.
The genetic material of all living organisms on Earth is made up of nucleic acids. However, scientists have long wondered how DNA and RNA first managed to form. Some have hypothesized that the Earth was seeded by comets or asteroids with the building blocks of life. But, until now, ribose, which is a key component of RNA, hadn't been detected on cosmic objects.
In this latest study, researchers created an artificial comet. They placed a representative mixture of water, methanol and ammonia in a high vacuum chamber at about -200 degrees Celsius. This allowed the researchers to simulate the formation of dust grains coated with ice, which is the raw material of comets.
The scientists then irradiated the material with UV and warmed the material to room temperature. Then, the scientists analyzed the composition of the synthetic comet in order to figure out exactly what components may have been useful to seed life.
So what did the researchers find? Surprisingly, the synthetic comet had several different sugars, including ribose. The diversity of the sugars and relative abundance suggested that they were formed from formaldehyde, which is a molecule found in space and on comets that forms in the presence of large quantities of methanol and water.
The findings show that ribose exists in synthetic comets created under lab conditions. However, scientists have yet to find ribose in real comets. With that said, the findings do show that it's feasible that comets delivered all of the building blocks of life within its interstellar ice.
The new research shows that comets may have actually seeded life on Earth. This is important when understanding how life on Earth first began. If seeded by comets, the Earth's climate likely helped foster these different materials and brought them together over time. This, in turn, helped jump-start our planet as we know it today.
The findings were published in the journal Science's April issue.
