Cambridge study challenges comet hypothesis for Earth's origin of life
Researchers at the University of Cambridge argue that high-speed comet impacts would likely destroy prebiotic molecules, making comet delivery of life's building blocks to Earth improbable.
A new study published in Scientific Reports questions the long-standing hypothesis that comets supplied the organic compounds needed for life on Earth. The research, conducted by scientists at the University of Cambridge, indicates that the extreme velocities and impact angles of typical comet collisions would vaporise most carbon- and nitrogen-bearing molecules, reducing the likelihood that they survived to seed the planet.
"Historically, scientists thought that comets were important for the origin of life on Earth, because they carried carbon- and nitrogen-bearing molecules, so these giant space snowballs were almost like a ‘get out of jail free card’ that brought all the molecules a planet would need to seed life," said lead author Dr. Richard Anslow of Cambridge’s Institute of Astronomy.
"It’s kind of a romantic idea, but our results suggest it’s highly unlikely," Anslow added.
The authors note that even a rare, favorable impact would need to occur under very specific conditions, and the resulting concentration of surviving molecules might still be insufficient for the emergence of life. They suggest that other sources, such as more frequent asteroid impacts, could have played a larger role in delivering prebiotic material.
The study also points out that smaller bodies like Mars, with a thinner atmosphere, might retain more of these molecules during comet impacts, though the researchers caution that this does not confirm any such delivery on Mars.
The findings prompt a reassessment of comet contributions to early Earth chemistry and highlight the need to explore alternative pathways for the origin of life.