From Paul Davies, University of Adelaide
Australia
There is a much more plausible explanation for why Earth-like organisms might
be found on Mars than the theory of Fred Hoyle and Chandra Wickramasinghe that
both Earth and Mars were seeded from space (This Week, 17 August, p 6). Microbes
could have colonised Mars from Earth in the same way as the putative fossil
Martians got here—cocooned in rocky ejecta from asteroid impacts.
When primitive life got going on Earth, our planet was still being heavily
bombarded from space. Billions of tons of microbe-laden rocks would have been
blasted aloft by these impacts. Shielded from cosmic radiation and comfortably
freeze-dried, these microorganisms could have survived for millions of years in
space—easily long enough to reach Mars and colonise it.
