In a paper published in the Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, researchers at the University of Cambridge analyzed the potential of cometary impacts to deliver the initial prebiotic molecules required for the origins of life on rocky exoplanets. They found that in order to deliver prebiotic molecules, comets need to be traveling relatively slowly — at speeds below 15 km per second; at higher speeds, the molecules would not survive — the speed and temperature of impact would cause them to break apart. The most likely place where comets can travel at the right speed are compact planetary systems, where a group of planets orbit closely together; in such a system, the comet could essentially be passed or ‘bounced’ from the orbit of one planet to another, slowing it down.
Comets are known to contain a range of the building blocks for life, known as prebiotic molecules.
For example, samples from the Ryugu asteroid, analyzed in 2022, showed that it carried intact amino acids and vitamin B3.
Comets also contain large amounts of hydrogen cyanide, another important prebiotic molecule.
The strong carbon-nitrogen bonds of hydrogen cyanide make it more durable to high temperatures, meaning it could potentially survive atmospheric entry and remain intact.
“We’re learning more about the atmospheres of exoplanets all the time, so we wanted to see if there are planets where complex molecules could also be delivered by comets,” said Dr. Richard Anslow, a researcher with the Institute of Astronomy at the University of Cambridge.
“It’s possible that the molecules that led to life on Earth came from comets, so the same could be true for planets elsewhere in the Milky Way Galaxy.”
Most of the comets in our Solar System sit beyond the orbit of Neptune, in what is known as the Kuiper Belt.
When comets or other Kuiper Belt objects collide, they can be pushed by Neptune’s gravity toward the Sun, eventually getting…
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