Chandra Wickramasinghe from Cardiff University, UK, has long argued the case for cometary
panspermia, the idea that comets are infected with primitive life forms and delivered life to the early Earth. That would explain why life on Earth arose so quickly after our planet formed around 4.5 billion years ...
Wickramasinghe says the case has been bolstered by NASA's Deep Impact probe, which blasted Comet Tempel 1 with a projectile in July 2005. Scientists reported seeing
clay particles spewing out from the interior. Because clay needs liquid water to form, Wickramasinghe says that suggests comets once had warm, liquid interiors due to heating from radioactive isotopes."
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