A team of British scientists from Cambridge has explored how comets might seed life on planets beyond our solar system and what conditions would make such delivery plausible. The research appears in a scientific journal known for summarizing advances in physics and astronomy. It investigates how complex organic molecules could be delivered to young planets under specific circumstances.
Employing a range of mathematical modeling techniques, the researchers show that comets could supply the basic building blocks for life, but only under particular scenarios. For planets that orbit a star similar to the Sun, a key parameter is the planet’s mass, which needs to be comparatively low to support an environment where these imported compounds could persist and contribute to prebiotic chemistry.
One of the central findings is that the speed of the incoming comet plays a decisive role. If a comet impacts a planet at velocities exceeding roughly 15 kilometers per second, the resulting heat can break down essential molecules, reducing the probability that life-supporting compounds would survive the impact and become available for subsequent chemical evolution.
In systems where planets lie relatively close to one another, comets may move with lower speeds and even switch from one orbital path to another, losing kinetic energy with each transition or “hop.” Such a sequence could keep impact velocities within a range that preserves fragile prebiotic molecules long enough to contribute to early chemistry on the surface.
Past investigations have noted that many comets carry compounds that are relevant to the origin of life. Analyses of samples from the Ryugu asteroid in 2022 revealed intact amino acids and vitamin B3, while other comets are known to host substantial amounts of hydrogen cyanide, a molecule of prebiotic interest that can feed complex chemical networks on a young planet.
As the researchers note, it is entirely possible that the very molecules enabling life on Earth originated in comets, suggesting a similar possibility for planets elsewhere in the galaxy. This perspective adds a potential universal thread to the story of how life might arise across the cosmos, not just here at home. [Attribution: Cambridge researchers, 2024 study, Journal of planetary science]
Astronomers also see practical value in these findings for guiding the search for life beyond the solar system. By identifying the combinations of planetary mass, orbital spacing, and typical encounter speeds that favor the survival of prebiotic compounds, scientists can better target exoplanetary systems where life might be more likely to emerge. This research supports a strategy for evaluating exoplanets based on the dynamical behavior of their small bodies, with a focus on how orbital architecture shapes delivery opportunities for life’s building blocks. [Attribution: Exoplanet habitability studies, 2024 review]
Earlier work that traced possible extraterrestrial origins of life in samples from asteroids similar to Bennu reinforced the notion that early Earth may have benefited from organic-rich material delivered through space rocks. This broader context strengthens the idea that the cosmos could be peppered with pathways to life, each shaped by the exact dance of comets, asteroids, and young planets in their stellar neighborhoods. [Attribution: Bennu-derived evidence, 2023 assessment]