Overview
- The University of Cambridge-led team published results Wednesday showing that comet impacts on early Earth usually occurred at speeds and angles that would heat and vaporize fragile molecules such as hydrogen cyanide (HCN).
- The researchers modelled HCN as a best-case test and found that survival would require a very large, slow, oblique impact on land, making meaningful delivery to Earth so rare it would be at best a one-off fluke.
- Simulations combined updated models of atmospheric entry, high-speed impacts, and comet dynamics to track how often comets could carry intact organics from space to a planet’s surface.
- The paper notes Mars would be modestly more permissive for cometary delivery because of its smaller size and thinner atmosphere, but it still judges comet delivery on Mars to be unlikely.
- Authors and outside scientists call for follow-up work to run similar models for carbon-rich asteroids and for more observational constraints, and they say the results should help refine targets and strategies in the search for life.