A century-old theory that comets delivered the building blocks of life to Earth may be incorrect, according to a recent study from the University of Cambridge. Scientists have long theorized that comets, rich in carbon- and nitrogen-bearing molecules, rained down prebiotics that could have initiated life on our planet. However, researchers found that the high speeds and sharp angles of comet impacts likely vaporized these crucial molecules.
"Historically, scientists thought that comets were important for the origin of life on Earth, because they carried carbon- and nitrogen-bearing molecules," said lead author Dr. Richard Anslow from Cambridge’s Institute of Astronomy. "It’s kind of a romantic idea, but our results suggest it’s highly unlikely."
The study, published in Scientific Reports, simulated comet impacts and determined that the conditions are generally not conducive to the survival of prebiotic molecules. Even in rare instances where some molecules might survive, the concentration would likely be too low to kickstart the complex chemical processes required for life.
"We can’t rule out for certain that it happened that way. But it seems to be a really rare occurrence – at best, a one-off fluke,” Anslow added.
The researchers suggest that other celestial bodies, such as asteroids, which strike Earth more frequently, could have been a more plausible source for life's initial ingredients. The study also noted that Mars, with its thinner atmosphere, might have been a more likely candidate for cometary delivery of prebiotic molecules, particularly during the early solar system's development.