Key facts
- The research argues that comet impacts were probably not a major source of the prebiotic molecules required for life to begin on Earth.
- Comets tend to strike Earth at speeds and angles that make organic survival unlikely, with most molecules vaporizing during impact instead of reaching the surface intact.
- Lab tests indicate that concentrated hydrogen cyanide can help form sugars, lipids and genetic building blocks.
- The team simulated short-period comet evolution and Earth impacts, including atmospheric entry, impact speeds and hydrogen cyanide survival during collisions.
A University of Cambridge-led team argues that comet impacts were probably not a major source of the prebiotic molecules required for life to begin on Earth, based on simulations reported Oct. 28, 2026. Prebiotic molecules are molecules involved in the origin of life. The finding challenges a long-held assumption about how life’s ingredients arrived on the planet.
The work challenges a cometary-delivery hypothesis that has persisted for roughly a century. SciTechDaily and EarthSky describe the finding as overturning that long-standing idea. The Cambridge-led team ran advanced computer simulations to test whether comets striking early Earth could have delivered hydrogen cyanide, a molecule central to pathways for producing essential building blocks of life.
The authors modeled short-period comet evolution and Earth impacts, including atmospheric entry, impact speeds and hydrogen cyanide survival during collisions, to see how often impacts could surmount delivery obstacles. Short-period comets are comets that orbit the Sun frequently. Of 100,000 simulated Earth bombardment histories, 54% showed no impacts delivering hydrogen cyanide at concentrations needed for prebiotic chemistry. Prebiotic chemistry refers to the chemical processes that could have led to the origin of life.
The authors presented the 54% figure as evidence that successful hydrogen cyanide delivery was rare across the simulated histories. Hydrogen cyanide is a carbon- and nitrogen-bearing compound that appears regularly in Solar System comets and takes part in reactions that can produce key building blocks of life. Lab tests show that concentrated hydrogen cyanide can help form sugars, lipids and genetic building blocks. Comets contain hydrogen cyanide and other organic compounds.
Comets tend to strike Earth at speeds and angles that make organic survival unlikely, with most molecules vaporizing during impact instead of reaching the surface intact. SciTechDaily attributes the problem to the violence of comet impacts, while Sci.News and Open Access Government describe extreme heat and atmospheric breakup destroying organics. Lead author Richard Anslow said on Oct. 28, 2026 that the required event would have to be a one-in-a-million occurrence and at best a one-off fluke, while noting it cannot be ruled out for certain.
The paper was posted to arXiv astro-ph.EP as identifier 2611.02924 version 1 on Nov. 2, 2026 at 10:52:47 UTC, submitted by Richard Anslow. Authors are Richard J. Anslow, Catriona H. McDonald, Amy Bonsor, Paul B. Rimmer and Auriol S. P. Rae. The authors also suggested Mars was somewhat more likely than Earth to receive prebiotic compounds from comets, yet the odds remained low.
The record connects the preprint to a Scientific Reports publication and DOI.
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