Tuesday, August 16, 2016

Life on Earth Began on.... Venus???

In the Golden Age of science fiction, Venus was the jungle world -- full of hot, steamy swamps populated by hot, steamy aliens. Ray Bradbury ("All Summer in a Day") imagined a world of constant rain. C.S. Lewis even set a version of the Garden of Eden on Venus in his novel Perelandra.

But the real-life Venus is no Eden -- it's blanketed by clouds of sulfuric acid (ouch!) with temperatures well above 800 degrees F. The surface of Venus is both dark and hot -- not too different from classical conceptions of hell. And did I forget to mention the atmospheric pressure? It's almost 100 times higher than the Earth's.

A typical Venusian, as portrayed on The Twilight Zone
But it's easy to see why science fiction writers were free to speculate about jungles and swamps all those years -- the surface of Venus is hidden by constant cloud cover (that sulfuric acid again!) making it impossible to probe until the advent of the space program. But now scientists at NASA have come up with a startling new idea: they suggest that Venus was at one time a balmy, hospitable place after all, and possibly suitable for life.

These NASA researchers used computer climate models to extrapolate backwards a billion or so years. Their results suggest that Venus could have been habitable as recently as 700 million years ago, if it had a shallow ocean on its surface.

But wait, there's more!  Annabel Cartwright (any relation to Angela Cartwright?) from Cardiff University took the argument one step further in this paper. She suggested that life might have originated on an early, habitable Venus and was then transported to Earth on asteroids, resulting in the "explosion" of biodiversity during the Cambrian period. So maybe we are all Venusians after all.

The Three Stooges visited Venus in the late 1950s


Kathy said...

Could multicellular organism survive 1) an asteroid impact and 2) transport on a fragment of the impact to earth via who-knows-what kind of route for who-knows-how-long?

Also, wasn't life already abundant on Earth, even if only at the single-cell level, by the time of the Cambrian Explosion?

Robert Scherrer said...

I think the argument is that it's single-celled organisms that get transported through space (not an argument I necessarily agree with). Although the nearly indestructible tardigrade could probably survive the trip. And I do believe that there was abundant life before the Cambrian -- it just exploded in a thousand weird directions during the Cambrian period.

Kathy said...

I can buy the notion of bacteria, and viruses, hitching a ride on Venusian or Martian ejecta and surviving entry into Earth. I do not see the need to suppose life originated elsewhere, as it does seem the elements and conditions for life to arise were present in the early Earth.

I also wonder whether we'll ever be able to prove Venus was once more hospitable, regardless of whether it ever produced life or not, given the life expectancy of probes landing there is measured in minutes.